Home range size and habitat use of the Eastern

Transcription

Home range size and habitat use of the Eastern Indigo Snake
(Drymarchon couperi) at a disturbed agricultural site in south Florida
A Thesis
Presented to
The Faculty of the College of Arts and Sciences
Florida Gulf Coast University
In Partial Fulfillment
of the Requirement for the Degree of
Master of Science
By S. Brent Jackson 2013
APPROVAL SHEET
This thesis is submitted in partial fulfillment of the requirements for the
degree of Master of Science
____________________________
Steven Brent Jackson
____________________________
Edwin M. Everham, III, Ph.D.
Committee Chair
____________________________
David W. Ceilley, M.S.
Committee Member
____________________________
John E. Herman, Ph.D.
Committee Member
The final copy of this thesis has been examined by the signatories, and we find that both the
content and the form meet acceptable presentation standards of scholarly work in the above
mentioned discipline.
III
Acknowledgements
My research would not have been possible without funding from the US Fish and
Wildlife Service and assistance and support from the Florida Fish and Wildlife Conservation
Commission as well as the Orriane Society. I would also like to thank my Committee: Dr.
Edwin M. Everham III, David W. Ceilley, and Dr. John E. Herman. Their advice, insight, and
support made this research a reality. I would also like to thank Dr. Billy Gunnels and Dr.
Marguerite Forest for their assistance and support in analyzing and presenting this research. My
gratitude also goes out to Colleen Clark for her countless hours in the field. Additionally, I
would like to thank the following individuals for their support and assistance in the field: Dr.
Jerry Jackson, Dr. Bette Jackson, Steve Mortallaro, Dana Dettmar, Jeff Talbott, Kory Ross, John
Ferlita, and Christian Lyon.
IV
Abstract
The Eastern Indigo Snake (Drymarchon couperi) is a species that is federally threatened
primarily because of habitat loss and fragmentation. Currently there is a paucity of data relating to
populations in the southern portion of this species range, which are believed to be different from
the northern populations due to climate and habitat factors. The objectives of this study were to
provide baseline data pertaining to home range size, habitat use, seasonal activity patterns, and
refugia use in disturbed habitats in south Florida using radio telemetry.
The field site for this study is the home to the future C-44 reservoir and stormwater
treatment area included in the Central and Southern Florida Project of the Comprehensive
Everglades Restoration Plan. It is an abandoned citrus grove intersected with canals, ditches, and
dirt roads located in western Martin County Florida.
A total of five snakes including four males and one female were sufficiently tracked for
analysis between the dates of January 2012 and March 2013. Total home range size varied from
9.71 - 65.78 ha. Several of the individuals tracked showed a preference for canal habitats
particularly during the winter months. All individuals tracked remained active all year long and
showed no significant difference in activity based on mean meters traveled per day when compared
between seasons. The two male snakes tracked for the longest period of time showed a significant
preference for artificial refugia in cooler temperatures and natural refugia in warmer temperatures.
D. couperi using the C-44 reservoir site demonstrate trends in home range size, habitat use,
seasonal activity patterns, and seasonal refugia preferences that differ from other populations of
this species. These differences highlight the need for conservation biologists to consider ecological
and behavioral differences across the range of a species, and within human-dominated landscapes,
when developing management plans. Understanding the role of disturbed habitats as possible
acceptable habitat for endangered and threatened species is integral to their continued survival.
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Table of Contents
Page
Acknowledgements
III
Abstract
IV
Table of Contents
V
List of Figures
VII
List of Tables
VIII
Chapter 1:
Introduction
Status
Taxonomy
Description
Range
Habitat
Refugia
Feeding
Reproduction
Home Range
Research Objectives
1
2
3
3
4
5
6
7
7
9
10
Study Site
Capture and Transmitter Implantation
Radio Tracking
Timeline
Analysis
Objective 1: Home Range
Objective 2: Habitat Preferences
Objective 3: Activity Patterns
Objective 4: Refugia Use
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Chapter 2:
Methods
Chapter 3:
Results
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Page
Chapter 4:
Discussion
Conclusions
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Literature Cited
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Appendix
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Appendix Table 1 Home Range Comparison Table
Appendix Table 2 Raw Data
Appendix Table 3 Key to Data
VII
List of Figures
Page
2.1 C-44 Study Area Map
2.2 C-44 Footprint Map
2.3 C-44 Weather with Seasonal Overlay
2.4 Canal Habitat Photo
2.5 Upland Habitat Photo
2.6 Great-Circle Distance Equation
2.7 Natural Refugia Photo
2.8 Artificial Refugia Photo
3.1 C-44 Indigo Snake Ranges
3.2 Monty Home Range
3.3 Vader Home Range
3.4 Dagwood Home Range
3.5 Paul Home Range
3.6 Nagini Home Range
3.7 Monty Winter Habitat Preferences
3.8 Monty Summer Habitat Preferences
3.9 Vader Winter Habitat Preferences
3.10 Vader Summer Habitat Preferences
3.11 Paul Winter Habitat Preferences
3.12 Paul Summer Habitat Preferences
3.13 Dagwood Winter Habitat Preferences
3.14 Nagini Winter Habitat Preferences
3.15 Nagini Summer Habitat Preferences
3.16 Nagini Seasonal Activity
3.17 Monty Seasonal Activity
3.18 Vader Seasonal Activity
3.19 Paul Seasonal Activity
3.20 Nagini Monthly Activity
3.21 Monty Monthly Activity
3.22 Vader Monthly Activity
3.23 Paul Monthly Activity
3.24 Monty Refugia Preferences
3.25 Vader Refugia Preferences
3.26 Nagini Refugia Preferences
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List of Tables
Page
2.1 Plant Species List
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3.1 Snake Home Ranges
23
3.2 Habitat Preferences
31
3.3 Average Daily Seasonal Movements
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3.4 Refugia Type Versus Air Temperature
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Appendix Table 1 Home Range Comparison Table
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Appendix Table 2 Raw Data
76
Appendix Table 3 Key to Data
88
1
Chapter 1
Introduction
We currently face a global biodiversity loss that can be attributed primarily to
anthropogenic practices (Landweber and Dobson, 1999). The magnitude of this loss is so great
that many scientists are calling this event the “sixth extinction” (Frankham et al., 2002).
Scientists estimate that we are losing up to 27,000 species a year in tropical forests alone (Myers,
1993). Many scientists believe that secondary extinction events may occur as an indirect result of
a disruption in the food chain (energy flow) that occurs during mass extinction events (Bruno
and Cardinale, 2008). Therefore, it is important to minimize the current threats to Earth’s
biodiversity while concurrently exploring the ecological response of organisms to such threats.
One of the greatest threats to biodiversity is habitat loss (Gibbons et al., 2000). Areas where
habitat loss is the most extreme show high extinction rates and have been identified as
biodiversity “hot spots” (Myers et al., 2000).
Habitat loss is the main reason for decline in more than 85% of threatened species in the
United States and is the primary cause of decline in over 97% of herpetofaunal species in the
United States (Wilcove et al., 1998). Habitat loss, degradation, and fragmentation are also the
driving causes for herpetofaunal loss on a global scale (Gibbons et al., 2000; Hyslop, 2007).
Habitat loss may be of particular importance to reptiles because of their spatial
requirements. This is in part because of their furtive nature, comparatively large home range
sizes, low population densities, low fecundity and the lack of frequent congregation events
(Gibbons et al., 2000). Current evidence suggests that reptile declines constitute a worldwide
crisis (Gibbons et al., 2000).
2
One reptile whose range and population have been affected by habitat loss is the Eastern
Indigo Snake (Drymarchon couperi). In addition to facing habitat lose and fragmentation, this
large predator is challenged by relatively low fecundity, large home range requirements
(USFWS, 2008), association to another listed species, the Gopher Tortoise (Gopherus
polyphemus), for low temperature refugia in the northern part of its distribution (Hyslop, 2007),
and the negative stigma commonly applied to snakes by the general public (Knight, 2008).
D. couperi also represents a species with little known about its spatial and habitat
requirements at the southern end of its distribution, despite being federally listed (Hallam et al.,
1998; Hyslop, 2007). Knowledge of basic life history and home range requirements are
paramount to understanding population trends and the effect habitat loss has on populations and
ultimately to preserving this species.
Status:
D. couperi was listed as federally threatened under the Endangered Species Act on March
3, 1978. Its listing was attributed to habitat modification, collection for the pet trade, and the
gassing of G. polyphemus burrows during rattlesnake roundups (Speake et al., 1981b; USFWS,
1978; 1998). At the time of listing the species range was already believed to be limited to
Georgia and Florida (USFWS, 1978). Presently the species is still listed as threatened and the
species large home range size and wide distribution have complicated the collection of accurate
population data (Hallam et al., 1998; USFWS, 2008). Since the species listing the enforcement
of laws has curtailed detrimental activities such as collection for the pet trade and burrow gassing
(Hyslop, 2007; Lawler, 1977; USFWS, 1978). Despite the lack of reliable population data the
continued loss and degradation of habitat points to the continued decline of this species
(USFWS, 1998).
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Taxonomy:
Holbrook first described the Eastern Indigo Snake in 1842 as Coluber corais. The type
locality for the first specimen was south of the Altamaha River in Georgia (Holbrook, 1842;
Hyslop, 2007). In 1853 Baird and Girard reassigned its genus to Georgia (Hyslop, 2007;
McCranie, 1980). In 1860 Cope reassigned the Eastern Indigo Snake yet again, this time to the
genus Spilotes (Hyslop, 2007; McCranie, 1980). In 1862 Cope declared the Eastern Indigo
Snake a subspecies of Spilotes corais (Hyslop, 2007; McCranie, 1980). Cope reassigned the
Eastern Indigo Snake a third time in 1900, this time to the genus Compsosoma (Hyslop, 2007;
McCranie, 1980). The current genus Drymarchon was assigned by Steineger and Barbour in
1917 (Hyslop, 2007; McCranie, 1980). Until recently Drymarchon was believed to be
monotypic through its range with multiple subspecies. The two subspecies found in the
southeastern United States included the Eastern Indigo Snake (Drymarchon corais couperi) and
the Texas Indigo Snake (Drymarchon corais erbennus) (Hyslop, 2007). In 1991 Collins
suggested that the Eastern Indigo Snake be raised to full species status because of geographic
separation and consistent differences in head scalation between it and the Texas Indigo Snake
(Collins, 1991). In 2001 the Society for the Study of Amphibians and Reptiles provisionally
accepted the raising of the Eastern Indigo Snake (Drymarchon couperi) to full species status
(Crother et al., 2001). Currently the genus Drymarchon contains five full species as well as five
subspecies (Wuster et al., 2001).
Description:
D. couperi is the longest snake in North America reaching lengths of up to 2.6 m
(Conant and Collins, 1998). Adult snakes range in size from 1.9 to 2.6 m in length
(Stevenson et al., 2009). They are uniformly black with a bluish sheen (Layne and Steiner,
4
1996). Additionally they have a variable reddish or cream coloration along their gular region
(Conant and Collins, 1998), though this coloring varies in extent and pigment. The scales of
this species are large and smooth with the exception of males who exhibit slight keeling on 1 to
5 middorsal scale rows (Layne and Steiner, 1996). D. couperi can be differentiated from the
Texas Indigo Snake (D. corais erebennus) by the lack of contact between the antepenultimate
supralabial scale and the temporal or postocular scales (Hyslop, 2007; Wright, 1957). Juvenile
D. couperi are similar in appearance to adults although some individuals display a blotched
dorsal pattern and more extensive ventral coloration (White and Garrott, 1990).
Range:
The genus Drymarchon is primarily a tropical genus that can be found from the
southeastern United States as far south as northern Argentina. The historic range of D. couperi
stretched from the coastal plains of Georgia, Alabama, and Mississippi, south to Florida (Carr,
1940; Diemer and Speake, 1983; Haltom, 1931; Moler, 1985a; USFWS, 2008). It is possible
that their range stretched as far north as southern South Carolina and as far west as southern
Louisiana (Hyslop, 2007; Smith, 1941). However, these additions to the species historical
range cannot be confirmed (USFWS, 1998). The current range of the species has been reduced
to Florida and the coastal plains of Georgia (Lawler, 1977; USFWS, 2008). The species is
now considered rare but it can still be found throughout peninsular Florida (Moler, 1985a;
USFWS, 2008). In the panhandle of Florida D. couperi is believed to persist in lower numbers
then the rest of Florida (USFWS, 2008). In south Florida, they are assumed to be concentrated
primarily in upland habitats. Their numbers are believed to be far less in wetland habitats such
as the Everglades (Duellman and Schwartz, 1958; Steiner et al., 1983).
5
Habitat:
The southeastern Coastal Plain is the herpetofaunal center of the United States
because it contains the highest diversity of reptile and amphibian species (Gibbons et al.,
1997; Trani, 2002). One of the reasons for this high diversity is due to unique habitats such
as longleaf pine forests (Landers et al., 1995). Longleaf pine forests represent areas of high
diversity supporting many organisms specifically adapted to the frequent disturbances such
as fire, and tropical storms (Landers et al., 1995). Many herpetofaunal species are endemic
to this habitat (Trani, 2002). Longleaf pine forests are home to 89 snake species including
three of the largest snake species in North America and seven species that are found nowhere
else (Trani, 2002). Of the original 30 million hectares of southeastern longleaf pine less than
1.2 million hectares of isolated fragments remain (Landers et al., 1995). This is less than
2% of its original extent. D. couperi remain important predators in this fragmented
ecosystem and the majority of research has focused on populations found within these
landscapes. However, this habitat does not represent the only habitat utilized by this species
(USFWS, 2008). Because of this populations that use different habitats are of particular
interest.
While D. couperi shows a preference for dry areas adjacent to water (Ernst and
Barbour, 1989), its range is large enough that climatic differences likely allow for the use of
different habitats depending on the snake’s geographic location. In Georgia D. couperi is
frequently found in sandhill habitats that also support populations of G. polyphemus (Speake et
al., 1978; Diemer and Speake, 1983). These sandhill communities are dominated by longleaf
pine-turkey oak forests (Hyslop, 2007; Wharton, 1977). These habitats are often used during
the winter months when burrow refugia is necessary in order to survive the cooler climate. In
6
summer months it is believed that snakes in the northern reaches of the geographic range move
away from the sandhills and occupy more hydric habitats such as river bottoms and wetlands
(Diemer and Speake, 1983; Lawler, 1977; Speake et al., 1981a).
Much of the species current range is located in Florida (Breininger, 2004). D. couperi
habitat use in Florida has historically been more varied than Georgia with snakes using habitats
such as mangrove swamps, wet prairies, xeric pinelands, hydric hammocks, citrus groves, and
scrub (Humphrey et al., 1992; Lawler, 1977). In the southernmost reaches of this species’
range tropical hardwood hammocks and pine uplands appear to be preferred, however
freshwater marshes, fallow fields, coastal prairie, mangrove swamps, and human impacted
habitats such as residential areas are also used to a lesser degree (Hyslop, 2007; Steiner et al.,
1983). These snakes are likely more habitat generalists than more northern individuals
because of climatic differences (USFWS, 2008). In south Florida D. couperi uses canal banks
where crab holes are commonly used as refugia in lieu of G. polyphemus burrows (Lawler,
1977; Speake et al., 1981a).
Refugia:
Throughout most of their range D. couperi require refugia for protection from extreme
temperatures, desiccation, and predators. They also serve as nesting sites (Holbrook, 1842;
Hyslop, 2007; Landers and Speake, 1980; Speake et al., 1981b; Speake et al., 1978). Studies
focused on water-loss in this species show that they are sensitive to desiccation and exposure to
direct sunlight with exposure times as short as ten minutes being fatal (Bogert et al., 1947; Ernst
and Barbour, 1989). The burrows created by G. polyphemus have been reported as particularly
important in the northern extent of the species range where they are heavily used in the winter
(USFWS, 2008). Additional refugia such as mammal burrows, stumps, logs, and debris piles are
7
also used for shelter (Lawler, 1977; Speake et al., 1978). Refugia use in the southern extent of
the species range has been considered less important because of the warmer climate (USFWS,
2008). D. couperi’s use of refugia in high temperatures has not been investigated.
Feeding:
D. couperi is characterized as a wide-ranging forager (Humphrey et al., 1992; Hyslop,
2007; Landers and Speake, 1980; Stevenson et al. 2010). It subdues prey items by chasing them
down and then immobilizing them with its powerful jaws (Keegan, 1944; Moulis, 1976;
Stevenson et al., 2010). D. couperi is not a constrictor (Stevenson et al., 2010). A study focused
on prey base of the Eastern Indigos determined that there were four major prey types utilized
throughout the snakes range. These prey items include anurans, G. polyphemus hatchlings,
snakes, and small mammals (Stevenson et al., 2010). In addition to hunting, D. couperi has been
documented scavenging carrion on multiple occasions (Stevenson et al., 2010). D. couperi is
capable of consuming large prey items such as Eastern Diamondback Rattlesnakes (Crotalis
adamanteus) as large as 1000 mm TL (Total Length) as well as adult Hispid Cotton Rats (Sigmodon
hispidus) (Stevenson et al., 2010). There is little known about the diet of hatchling and juvenile D.
couperi (Stevenson et al., 2010), but they are known to consume invertebrates as well as prey items
similar to adults (Layne and Steiner, 1996; Stevenson et al., 2010). The diverse diet and high vagility
of this species allow it to forage successfully in numerous habitats (Breininger et al., 2004; Hyslop,
2007; Speake et al., 1978; Stevenson et al., 2010).
Reproduction:
Gillingham and Chambers (1980) described courtship behavior. They broke the behavior
into three phases. During Phase I the male pursues the female and begins courtship. During Phase II
alignment and tail searching occur in preparation for intromission. During Phase III intromission
8
occurs. The entire courtship and copulation process can last over four hours (Gillingham and
Chambers, 1980). Information relating to reproduction in D. couperi is limited with most data
coming from captive populations (Hallam et al., 1998; Hyslop, 2007). Available reproductive
timelines for this species differ across their range and are therefore represented as broad periods of
time. The breeding season is considered to last from October through March (Groves, 1960;
Humphrey et al. 1992; Speake et al., 1978; Steiner et al., 1983). However, It is believed that it may
extend into April in Georgia (Hyslop, 2007; Moulis, 1976). D. couperi is oviparous and lays
clutches of four to 12 eggs (Speake et al., 1987; Steiner et al., 1983). The eggs range from 37 to 89 g
in mass (Speake et al., 1987; Steiner et al., 1983). The gestation period for this species can last for
130-140 days (Hyslop, 2007; Speake et al., 1987). Eggs hatch after approximately three months,
primarily between the months of August and September (Groves, 1960; Wright, 1957). Recorded
hatchling total length varied from 340–485 mm (Ernst and Barbour, 1989). Multiple studies
looking at sex ratios of hatchlings and juveniles show a 1:1 ratio of males to females (Moulis,
1976; Steiner et al., 1983). This ratio is reported as altered in adult snakes with males being more
numerous than females. A south Florida study reported an adult sex ratio of 1.54 males: 1 female
(Layne and Steiner, 1996). In a study using similar methods, Stevenson found an adult sex ratio of
2.1 males: 1 female in Georgia (Hyslop, 2007).
Sexual maturity is reached at 1500 mm total length (Layne and Steiner, 1996; Speake et al.,
1987). In a study of captive female snakes, sexual maturity was reached in three to four years
(Moulis, 1976). During the same study, Moulis noted that captive snakes commonly lay eggs
every year (Moulis, 1976). A two-year study of a wild population found that three of the five
females studied were gravid both years (Bolt, 1996). The maximum-recorded age of D. couperi in
captivity was 25 years 11 months (Snider and Bowler, 1992).
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Home Range:
Understanding the effect of habitat loss on a species requires knowledge of the species
current use of the habitat (Hyslop, 2007). Unfortunately the secretive behavior, low densities,
and large home-range size of D. couperi make it difficult to obtain these data using traditional
field study techniques (Hyslop et al., 2009b; Parker and Plummer, 1987). Mark-recapture
studies are commonly used to determine population and home range size but are mostly
ineffective for D. couperi because of low recapture rates (Hyslop et al., 2009b; Parker and
Plummer, 1987). One field technique that has proven to be successful with D. couperi is radio
telemetry (Hyslop, 2007; Speake et al., 1978). Radio telemetry is time intensive and expensive
but ensures a greater likelihood of relocating individuals (Hyslop et al., 2009b). In addition
the transmitter implantation required for this type of study has been proven safe for D. couperi
(Hyslop et al., 2009b).
Previous studies looking at home range sizes of D. couperi have been carried out in
both southern Georgia and peninsular Florida with multiple studies carried out in southern
Georgia. Early studies primarily used relocated and captive bred specimens. These studies
found home range sizes ranging from 4.8 to >300 ha (Dodd and Barichivich, 2007; Moler,
1985b; Speake et al., 1978; Appendix Table 1). More recent studies on wild populations in
Georgia found home range sizes ranging from 35 to 1,530 ha, with male home ranges ranging
from 140 to 1,530 ha and female home ranges ranging from 35 to 354 ha (Hyslop, 2007).
These are the largest recorded home range size of any North American snake species (Hyslop,
2007). Other radio-telemetry studies conducted in Georgia show seasonal activity patterns
with smaller home range sizes during the winter months and home range expansion during the
summer months (Hyslop, 2007; Speake et al., 1978).
10
Radio telemetry studies conducted with D. couperi in peninsular Florida found home
range sizes ranging from 65 to 300 ha for males and 30 to 115 ha for females (Bolt, 2006;
Hyslop, 2007). A study conducted in northern Florida found home range sizes for males
ranging from 23 to 281 ha, (Hyslop, 2007; Moler, 1985b). A more recent study carried out in
central and east central Florida found home ranges between 12.8 – 538.4 ha (Breininger et al.,
2011). The southernmost telemetry study was carried out at Archbold Biological Station in
central Florida (Layne and Steiner, 1996). This study tracked 19 individuals and found the
average male home range to be 74.3 ha for males and 18.6 ha for females (Layne and Steiner,
1996). Home range sizes for southern populations of D. couperi remain a mystery.
Research Objectives:
To understand how habitat alteration will impact a species, it is important to first
understand the basic life history of the organism. Spatial requirements including home range
area, use of different habitat types, and seasonal changes in habitat use are key factors in
understanding the effect of habitat perturbations on the species
The goal of this study is to elucidate home range size, seasonal activity patterns,
differential habitat use, and refugia preferences of a population of D. couperi at an abandoned
agriculture site in southeastern Florida. The collection and analysis of this data is necessary to
provide guidance for the regional conservation management efforts of the species and provide
a baseline for future research. It will also serve to highlight possible intraspecific differences
that may relate to variation in climate and habitat differences throughout the species range.
1. Determine home range size of D. couperi in south Florida.
a. Describe total home range sizes of individuals
b. Examine seasonal (winter/summer) differences in home range size.
11
2. Determine habitat preferences of D. couperi in south Florida.
a. Describe habitat preferences of individuals
b. Examine seasonal (winter/summer) differences in habitat preferences.
3. Determine activity patterns of D. couperi in south Florida.
a. Describe overall activity patterns of individuals.
b. Examine seasonal (winter/summer) differences in activity patterns.
4. Describe refugia utilization of D. couperi in south Florida.
a. Describe refugia utilization by individuals.
b. Examine differences in refugia utilization in regards to air temperature.
12
Chapter 2
Methods
Study Site:
The field site for this study is an abandoned citrus grove area intersected with canals,
ditches, and dirt roads located in western Martin County Florida. The site will be home to the
future C-44 reservoir and storm water treatment area included in the Central and Southern
Florida Project of the Comprehensive Everglades Restoration Plan (USACOE, 2004). Prior to
agricultural use the site was likely similar to the surrounding Allapattah Flats Wildlife
Management Area, mixed slash pine and saw palmetto, with hardwood hammocks of oak and
sabal palm and patches of seasonal wetlands and marshes.
Figure 2.1 Map of study area
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Figure 2.2 Aerial photo of C-44 footprint. Features in the southwest corner of the area are test
impoundments. Linear north/south features throughout the site are the ridges and swales
associated with the citrus orchard. Swales become seasonal wetlands.
The total C-44 project area is 4,856 ha and will contain a 4.6 m deep, 1,376 ha reservoir
(USFWS, 2006). Tree clearing and removal took place in 2006-2009. Removal of trees was
done using a backhoe and trees were piled and burned on site. Efforts were made to keep piles
away from canals and ditches were D. couperi had been previously sited (USFWS, 2006). The
citrus operation buildings are located within the footprint of the future reservoir and were
abandoned but still standing during the field portion of the study. In addition to buildings there
are abandoned equipment and pipes left over from the citrus operations during the course of the
study.
14
The study site for this research was limited to the 1,376 ha footprint of the future
reservoir. The reservoir footprint is dominated by native and non-native grasses and shrubs and
has limited canopy cover. Canals, ditches, and swales were typically covered with a mixture of
native and exotic aquatic and wetland vegetation throughout the site.
Table 2.1 List of most common plant species observed on the C-44 site.
Plant species list
Elephant Grass (Pennisetum purpureum)
Lantanas (Lantana sp.)
Smut Grass (Sporobolis indicus)
Beggar-Ticks (Bidens pilosa)
Common Ragweed (Ambrosia artemisiifolia)
Cogon Grass (Imperata cylindrica)
Dog Fennel (Eupatorium capillifolium)
Salt Bush (Baccharis halimifolia)
Brazilian Pepper (Schinus terebinthifolius)
Sabal Palm (Sabal palmetto)
Southern Wax Myrtle (Myrica cerifera)
Coastal Plain Willow (Salix caroliniana)
Bushy Bluestem (Andropogon glomeratus)
Yellowtop (Flaveria linearis)
Duck Potato (Sagittaria lancifolia)
American Crinum (Crinum americanum)
Pickerelweed (Pontederia cordata)
Torpedo Grass (Panicum repens)
Para Grass (Brachiaria mutica)
West Indian Marsh Grass (Hymenachne amplexicaulis)
Water Lettuce (Pistia stratiotes)
Water Hyacinth (Eichhornia crassipes)
Cattail (Typha sp.)
Fragrant Water Lily (Nymphaea odorata)
D. couperi had been documented within the study site and will be directly affected by the
construction and maintenance of the C-44 reservoir and surrounding storm water treatment areas
(USFWS, 2006). Biological surveys carried out in 2005 included one road kill and two live D.
15
couperi within the study area (USFWS, 2006). In addition, grove operators stated that D.
couperi were most often seen along roads and ditches on the property (USFWS, 2006).
The biological opinion for the site stated that many of the D. couperi sightings occurred
in the northern portion of the property bordering Allapattah Flats Wildlife Management Area
(USFWS, 2006). Population estimates for D. couperi were calculated using population estimates
from Archbold Biological Station, which assumes 2.6 snakes for every 100 ha (Layne and
Steiner, 1996; USFWS, 2006). All 4,856 ha of future reservoir and STA sites are classified as
D. couperi habitat. The use of a micro-irrigation system for the sites citrus operations provides
better snake habitat compared to a furrow-irrigated system, which requires additional flooding of
the land (USFWS, 2006). Due to the size of the study area, the US Fish and Wildlife Service
(USFWS), basing their estimate on D. couperi population density at Archbold Biological Station
(Highlands County, Florida), predicted that up to 126 adult D. couperi may be present at the C44 site. They also believed that the C-44 site represents less suitable habitat than that at
Archbold Biological Station. Thus they stated there are likely fewer than 126 adults at the C-44
site (USFWS, 2006).
Capture and Transmitter Implantation:
United States Fish and Wildlife Service permits allowed for the implantation of radiotelemetry transmitters in up to five adult D. couperi. The transmitters used for this study were
Holohil Systems (Holohil Systems Ltd., Carp, Ontario) SI-2T internal transmitters. The
transmitters weigh 13 grams per transmitter, including batteries that are rated for an average of
two years of field use. Dr. Darryl Heard, (University of Florida, College of Veterinary
Medicine), supervised the implantation of the transmitters within the coelomic cavity of snakes
at the Small Animal Hospital at the University of Florida in Gainesville.
16
Snakes were hand captured opportunistically while conducting walking surveys in areas
where individuals were reportedly seen. A concurrent study being carried out by the USFWS
used coverboards as refugia to attract snakes and other herpetofauna to determine whether they
were present at the site. Areas around coverboards, abandoned buildings, and along canal banks
were frequently searched for snakes.
Captured individuals were examined to determine their sex and health. Sex was
preliminarily determined by looking for the presence of keels on middorsal scales, which are
characteristic of males (Layne and Steiner 1984; 1996; Stevenson et al., 2003). Any observation
related to health such as external damage and overall appearance of the skin were recorded at the
time of collection. All tracked snakes were sexed by examining genitalia at the time of
transmitter implantation.
For optimal post-surgery healing, individuals that appeared to be preparing to shed were
held until shedding occurred. Snakes were then transported to the University of Florida for
transmitter implantation. After surgery the snakes were held at Florida Gulf Coast University to
recuperate from the anesthesia and surgery. Snakes were typically held for three to five days
before being released back at the capture location. Typically snakes were released at the nearest
refugium to the site of capture. Implanted snakes were given a name in order to keep track of
individuals’ records to identify transmitter frequencies, and for ease of use in discussion.
Radio Tracking:
Individuals were tracked a minimum of twice a week and a minimum of once a day
during each tracking event. Tracking of individuals began immediately following release.
Snakes were tracked using a Communication Specialists (Communications Specialists, Inc.,
Orange, California) handheld yagi antenna and car-mounted roof antenna in conjunction with an
17
R-1000 handheld receiver. Once an individual being tracked was located, its location was
recorded using a handheld GPS unit. The observer recorded air temperature, atmospheric
conditions, and whether the snake was above ground or below ground. Information regarding
habitat and refugium type was also collected when applicable. Occasionally snakes were
recaptured to briefly examine their condition.
Timeline:
Our search for D. couperi at this site began in December 2011. As individuals were
captured they were implanted and released for tracking, so the duration of sampling varied
among the snakes. Data collection for this study was concluded at the end of one year.
Surviving snakes will continue to be tracked for an additional year after this study. At the
conclusion of the second year snakes will be recaptured and taken back to the University of
Florida Small Animal Hospital for transmitter removal. After recovery snakes will be released
back at the last site of capture.
Analysis:
Data were entered into Microsoft Excel for organization and were then imported to
ArcGIS 10.1 for spatial analysis and R package 3.0.1for statistical analysis. Seasons were
differentiated using ArcGIS 10.1 in conjunction with NOAA’s southeast Florida seasonal climate
categorization which used 42 years of temperature, dew point, and precipitation data to break the
year into two seasons: winter and summer (NOAA, 2009). The day summer started and winter
ended was May 21. The day that summer ended and winter started was October 17 (NOAA,
2009). These two dates provide the cutoff points for each season for this study (Figure 2.3).
18
Figure 2.3 Monthly average temperature and precipitation during study with lines delineating
seasonal breaks as determined by NOAA (2009). Monthly averages provided by Weather
Underground’s Indiantown station.
Minimum bounding geometry polygons were created in ArcGIS in order to estimate
individual home ranges. Minimum bounding geometry (also commonly referred to as minimum
convex polygons) takes the sampled locations of each individual and creates the smallest
possible polygon using all included points. Kernel density estimations were also created using
ArcGIS to show high activity areas within home ranges. Kernel density estimations look at the
frequency at which an individual was sampled per square meter. This provided a visual
representation (color coded) for heavily used areas that would otherwise be represented only as
overlaying points. Representations of seasonal home ranges were similarly generated using
ArcGIS and NOAA designated seasons. This was accomplished using minimum bounding
19
geometry polygons that were comprised of points collected between the corresponding dates for
each season.
The statistical package “R” was used to run a non-parametric binomial test to evaluate
habitat preferences between canal bank habitats (Figure 2.4) versus upland habitats (Figure 2.5)
in relation to seasonality. This test uses the proportion of each habitat type on the landscape as
the ‘expected’ frequency of habitat use and determines if the organism’s selection of the habitat
is non-random, i.e. shows a preference.
Figure 2.4 Canal habitat
Figure 2.5 Upland habitat
In order to differentiate habitats and determine their availability ArcGIS was used to select all
canals present within each individual’s seasonal ranges. The Florida Geographical Database Library
provided canal layers for Martin County. Selected canals were assigned an average width of 12
meters. All canals were assigned this width based on estimates from visual inspections at the field
site. In addition to the 12-meter wide canals an additional buffer was extended out 10 meters on
either side of the canal. The resulting canal and buffer area was used to represent canal habitat; their
areas were calculated within ArcGIS. The term “canal habitat” includes the actual water body,
20
associated vegetation, canal banks, all structures in canals (drainage pipes, culverts, weirs, pump
stations), and the adjacent spoil uplands up to 10 meters on both sides of the canal, which often
includes agricultural access roads. The remaining habitat for each individual was classified as
upland habitat. The upland habitat is characterized as citrus grove fields with all citrus trees
removed. This “upland habitat” includes linear ridges, where citrus trees were planted and
adjacent swales that facilitated irrigation of the root zone. These seasonally flooded irrigation
swales are included in the generalized “upland habitat” category, and were not included as canals
or canal habitat because they were too narrow and shallow to be classified by the South Florida
Water Management District. These features were lumped in with upland habitat for this analysis.
The percentage of available canal habitat was then used in the binomial test. The statistical
significance of canal use for each season was examined in relation to the availability of canal habitat
for each snake during each season.
Activity patterns were calculated by using the great-circle distance equation to calculate the
minimum distance between data points (Nichols et al., 2000). This equation takes two points on the
surface of a sphere and determines the shortest distance between them.
Figure 2.6 Great-circle distance equation used to determine distance between sampling points
Once the distance between sampling points was determined it was divided by the number
of days between sampling events to determine daily movements. Average movement was
determined for individuals by calculating mean meters per day movement. When individuals
were located in the same location on successive tracking events an average daily movement of
21
zero was assumed. One sampling event was used per day and time of day in which sampling
occurred was not taken into account. For days where individuals were located more than once
during a single day the first location of the day was used. No weighting was used to account for
differences in days between sampling events. A non-parametric one-way permutation test was
then run in “R” using NOAA’s seasonal climate categories to test for differences in activity
patterns between seasons and among months.
Refugia types were categorized as natural (Figure 2.7) or artificial (Figure 2.8). Natural
refugia included those made by mammals such as the burrows of Nine-banded Armadillos
(Dasypus novemcinctus) and Hispid Cotton Rats (Sigmodon hispidus), and any other naturally
occurring shelter. Artificial refugia included pipes, buildings, and waste left behind from citrus
operations. For this analysis, concrete piles and concrete waste were classified as artificial
refugia.
Figure 2.7 Natural refugia
Figure 2.8 Artificial refugia
Air temperature was recorded during every sampling event and represents the air
temperature at the time sampling occurred. Air temperature data were collected using a digital
handheld thermometer. Locations where snakes were found in refugia were organized by type
and compared in relation to air temperature using “R” to run a one-way permutation test.
22
Chapter 3
Results:
A total of seven snakes including four males, two females and one juvenile of
undetermined sex were tracked between the dates of January 2012 and March 2013. Of these
snakes three were sampled at least 98 times; Monty was located a total of 107 times while Vader
and Nagini were both located 98 times (Table3.1). Two of the four remaining snakes were
successfully tracked enough times to include in analysis; Paul was located 35 times and
Dagwood 38 times (Table 1.1). The other two snakes were not included in the analysis due to
small sample size; Bette, a female, was located six times before being predated and Junior, a
juvenile, was successfully tracked 14 times before the external transmitter was shed.
After the field portion of this study was complete, polygons representing the home range
of each snake were established using minimum bounding geometry (Figure 3.1). Total home
range size ranged from 9.71 ha – 65.78 ha. Two males were tracked for every month of the year;
Monty had the largest total home range at 65.78 ha (Table 3.1 and Figure 3.2) and Vader had the
second largest total home range at 45.06 ha (Table 3.1 and Figure 3.3). The two other males
were tracked for less than 6 months out of the year; Dagwood had the third largest total home
range at 36.89 ha (Table 3.1 and Figure 3.4) and Paul had the fourth largest total home range at
23.52 ha (Table 3.1 and Figure 3.5).
Nagini, the only female included in the analysis, was
tracked every month of the year; she had the smallest recorded total home range at 9.71 ha
(Table 3.1 and Figure 3.6).
Home ranges were broken into two seasons based on NOAA season categorization for
southeast Florida (NOAA, 2009). Winter home ranges included a maximum of 58.42 ha
23
(Monty; Table 3.1 and Figure 3.2) and a minimum of 1.96 ha (Nagini; Table 3.1 and Figure 3.6).
Summer home ranges included a maximum of 21.59 ha (Paul; Table 3.1 and Figure 3.5) and a
minimum of 9.71 ha (Nagini; Table 3.1 and Figure 3.6). Both Monty and Vader had larger
winter ranges than summer ranges, while Paul and Nagini displayed larger summer ranges than
winter ranges (Table 3.1).
Table 3.1 Snake home ranges for all snakes successfully tracked at least 35 times during the
course of the study. All sampling points were grouped to create home ranges represented by
Minimum Bounding Geometry polygons. Seasonal home ranges were calculated for individuals
with at least nine sampling events per season using the same technique.
Points
Winter Range
Summer Range
Total Home
Snake
Sex
Collected
(ha)
(ha)
Range (ha)
107
M
58.42
17.73
65.78
Monty
98
M
42.44
20.81
45.06
Vader
38
M
21.7
36.89
Dagwood
35
M
6.5
21.59
23.52
Paul
98
F
1.96
9.71
9.71
Nagini
24
Figure 3.1 Extent of the study area and minimum bounding geometry polygons using
ArcGIS 10.1, for all snakes tracked
25
Figure 3.2 Monty’s (male) total home range (top panel) as well as his winter and summer ranges
(bottom panels, black outlines represent total home range for comparison). All ranges were
created as minimum bounding geometry polygons with kernel density estimations highlighting
sampling occurrences per meter squared using ArcGIS 10.1.
26
Figure 3.3 Vader’s (male) total home range (top panel) as well as his winter and summer ranges
27
Figure 3.4 Dagwood’s (male) home range. This range was created as a minimum bounding
geometry polygon with kernel density estimations highlighting sampling occurrences per meter
squared using ArcGIS 10.1. No seasonal maps were created for Dagwood because he was not
tracked through the summer season.
28
Figure 3.5 Paul’s (male) total home range (top panel) as well as his winter and summer ranges
29
Figure 3.6 Nagini’s (female) total home range (top panel) as well as his winter and summer
ranges (bottom panels, black outlines represent total home range for comparison). All ranges
were created as minimum bounding geometry polygons with kernel density estimations
highlighting sampling occurrences per meter squared using ArcGIS 10.1.
30
Three male snakes and one female, (Monty, Vader, Paul and Nagini,) had enough sampling
points throughout the year to analyze seasonal habitat preferences for both seasons, while an
additional male (Dagwood) only had enough sampling points to look at habitat preferences during
the winter season (Table 3.2). The seasonal ranges for each snake were separated into two different
habitat types. Canal habitat consists of the canals and a ten-meter buffer along each side of the canal.
The remaining habitat within the seasonal range was classified as upland habitat. A one-way
permutation test was used to determine whether a significant preference for canal habitat exists for
each snake during each season based on the number of times canal habitat was used compared to the
percent of canal habitat within each snake’s seasonal home range.
Monty (Figures 3.7 and 3.8), Vader (Figures 3.9 and 3.10), and Paul (Figures 3.11 and 3.12)
showed a larger percentage of available canal habitat in their winter home ranges than in their
summer home ranges and all three were located more often in those canal habitats, demonstrating a
statistically significant preference for canal habitat, during the winter season (Table 3.2). Dagwood,
however, showed no significant canal habitat preference during the winter season (Table 3.2 and
Figure 3.13). Additionally, Vader was the only male to show a significant canal habitat preference
during the summer season (Table 3.2 and Figure 3.10). Interestingly, Nagini, the only female,
showed a conflicting trend from the males with a higher percent of available canal habitat during the
summer rather than winter season (Table 3.2). Also, except for Dagwood in the winter season,
Nagini’s seasonal home ranges contained the greatest percent of available canal habitat and she
showed a significant preference for those canal habitats during both seasons (Table 3.2 and Figures
3.14 and 3.15).
31
Table 3.2 Habitat use for all individuals sampled at least 35 times over the course of the study.
Canal habitat includes the canal itself as well as a ten-meter buffer along each side of the canal.
All other habitat was considered upland habitat. The percent of canal and upland habitat was
calculated based on the availability of each habitat type within each snake’s seasonal home ranges.
Seasons were based on NOAA seasonal data for southeast Florida (NOAA, 2009). The p-value
represents a one-way permutation test looking at preference for available canal habitat over
available upland habitat for each snake during each season. The color red denotes a significant pvalue.
Snake and Season
Monty Winter
Monty Summer
Vader Winter
Vader Summer
Paul Winter
Paul Summer
Dagwood Winter
Nagini Winter
Nagini Summer
%Canal
Habitat
10.7
0.6
3.7
1.5
8.0
7.5
19.7
18.5
34.2
Canal
Points
30
1
7
4
3
4
8
8
13
%Upland
Habitats
89.3
99.4
96.3
98.5
92.0
92.5
80.3
81.5
65.8
Upland
Points
35
40
56
30
6
22
30
29
3
P-Value
8.60E-14
0.2187
0.01278
0.004596
0.02979
0.1501
0.8369
0.0001461
2.07E-09
32
Figure 3.7 This figure displays Monty’s (male) winter habitat preferences. Habitats were broken
into two categories. Canal habitat includes the canal and a 10-meter buffer on either side of the
canal. Upland habitats represent all other available habitat within the winter home range.
During the winter season 10.7% of Monty’s winter home range was canal habitat and 89.3% was
upland habitat. The P-value represents a one-way permutation test looking at preference for
available canal habitat over available upland habitat during the winter season.
33
Figure 3.8 This figure displays Monty’s (male) summer habitat preferences. Habitats were
broken into two categories. Canal habitat includes the canal and a 10-meter buffer on either side
of the canal. Upland habitats represent all other available habitat within the winter home range.
During the summer season 0.6% of Monty’s winter home range was canal habitat and 99.4% was
34
Figure 3.9 This figure displays Vader’s (male) winter habitat preferences. Habitats were broken
During the winter season 3.7% of Vader’s winter home range was canal habitat and 96.3% was
35
Figure 3.10 This figure displays Vader’s (male) summer habitat preferences. Habitats were
During the winter season 1.5% of Vader’s summer home range was canal habitat and 98.5% was
36
Figure 3.11 This figure displays Paul’s (male) winter habitat preferences. Habitats were broken
During the winter season 8.0% of Paul’s winter home range was canal habitat and 92.0% was
37
Figure 3.12 This figure displays Paul’s (male) summer habitat preferences. Habitats were
During the winter season7.5% of Paul’s summer home range was canal habitat and 92.5% was
38
Figure 3.13 This figure displays Dagwood’s (male) winter habitat preferences. Habitats were
During the winter season 19.7% of Dagwood’s winter home range was canal habitat and 80.3%
was upland habitat. The P-value represents a one-way permutation test looking at preference for
39
Figure 3.14 This figure displays Nagini’s (female) winter habitat preferences. Habitats were
During the winter season 18.5% of Nagini’s winter home range was canal habitat and 81.5% was
40
Figure 3.15 This figure displays Nagini’s (female) summer habitat preferences. Habitats were
During the winter season 34.2% of Nagini’s summer home range was canal habitat and 65.8%
was upland habitat. The P-value represents a one-way permutation test looking at preference for
41
In order to determine seasonal activity patterns individuals had to be sampled at least nine
times during both winter and summer seasons. A total of four snakes were sampled enough times to
be included in this analysis (Table 3.3). Mean meters travelled per day was determined by taking the
distance travelled between tracking events, and dividing by the number of days between tracking
events, and then averaging movements for both seasons.
Average daily winter movements ranged from 88.05 m – 13.37 m. Average daily summer
movements ranged from 68.05 m – 41.79 m. Averages between the two seasons were tested to
determine whether movements were significantly different or not using a one-way permutation test.
Nagini, the female snake, showed a difference in activity between seasons that approached statistical
significance (Table 3.3 and Figure 3.16). However, the three male snakes, Monty (Figure 3.17), Vader
(Figure 3.18), and Paul (Figure 3.19) showed no significant difference (Table 3.3).
In addition to looking at activity differences between seasons, monthly activity patterns were
also tested for significance in Nagini, Monty, Vader, and Paul (Figures 3.20, 3.21, 3.22, and 3.23,
respectively). Breaking the activity patterns into a finer scale yielded similar results, with only Nagini
(Figure 3.20) showing a significant difference among monthly activity patterns.
Table 3.3 Activity patterns for all individuals that were located at least nine times in both the
summer and winter seasons. Average daily seasonal movements were determined by measuring
the distance between two consecutive sampling events and dividing that distance by the number
of days between events, and then averaging the daily movements for each season. Seasons were
based on NOAA seasonal data for southeast Florida (NOAA, 2009). The P-value was calculated
using a one-way permutation test.
Average Winter
Average Summer
Winter
Summer
Snake
Movements
Movements
P-Value
Points
Points
(m/day)
(m/day)
13
13.37
74
41.79
0.05761
Nagini
50
52.67
39
50.71
0.8595
Monty
43
88.05
33
68.05
0.5499
Vader
9
26.99
23
64.12
0.2445
Paul
42
50
100
150
200
250
300
p = 0.05921
0
Average Minimum Distance Traveled Per Day in Meters (+/- 95%)
350
Nagini
Summer
Winter
Seasons
Figure 3.16 This figure displays Nagini’s (female) activity during the winter and summer seasons
based on mean meters traveled per day. Seasons were based on NOAA seasonal data for
southeast Florida (NOAA, 2009). The dark horizontal bars in this figure represent the median.
The boxes represent the 25th to 75th percentiles. The error bars represent the 5th to 95th
percentiles. Circles represent individual data points outside the 5th or 95th percentiles. The Pvalue was calculated using a one-way permutation test.
43
50
100
150
p = 0.8595
0
Monty
Summer
Winter
Seasons
Figure 3.17 This figure displays Monty’s (male) activity during the winter and summer seasons
44
200
400
600
800
p = 0.5499
0
Vader
Summer
Winter
Seasons
Figure 3.18 This figure displays Vader’s (male) activity during the winter and summer seasons
45
400
100
200
300
p = 0.2445
0
Paul
Summer
Winter
Seasons
Figure 3.19 This figure displays Paul’s (male) activity during the winter and summer seasons
46
P-value =0.0012
Figure 3.20 This figure displays Nagini’s (female) monthly activity in mean meters traveled per
day. The error bars represent the 5th to 95th percentiles. The P-value was calculated using a oneway permutation test.
47
P-value =0.9784
Figure 3.21 This figure displays Monty’s (male) monthly activity in mean meters traveled per
48
P-value =0.1663
Figure 3.22 This figure displays Vader’s (male) monthly activity in mean meters traveled per
49
P-value =0.09911
Figure 3.23 This figure displays Paul’s (male) monthly activity in mean meters traveled per day.
The error bars represent the 5th to 95th percentiles. The P-value was calculated using a one-way
permutation test.
50
Use of refugia was examined in relation to air temperature. Individuals had to be tracked
through every month of the year in order to be included in this analysis. Therefore, three
individuals were included in this analysis. Refugia categories were broken into artificial and
natural. Available artificial refugia used during the course of the study included buildings, septic
tanks, pipes, and rock piles left behind from citrus operations. Additional artificial refugia were
placed at the field site for a concurrent D. couperi study being carried out by the US Fish and
Wildlife Service and the Florida Fish and Wildlife Conservation Commission, which included
artificial burrows and coverboards. Natural refugia available at the site can be primarily
characterized as mammal burrows. Correlations between refugia type and air temperature were
analyzed using a one-way permutation test (Table 4.1).
Monty (Figure 4.1) and Vader (Figure 4.2) both showed a statistically significant
preference for artificial refugia in cooler temperatures and natural refugia in warmer
temperatures (Table 4.1). Nagini (Figure 4.3) showed no significant preference for refugia type
in relation to air temperature (Table 4.1).
Table 3.4 Relationship between refugia type and air temperature. The p-value was calculated
using a one-way permutation test. Natural refugia included mammal burrows. Artificial refugia
included man-made structures, pipes, rock piles, cover boards, and artificial burrows.
Snake
Artificial
Refugia
Points
Monty
Vader
Nagini
21
35
26
Average Temp.
When found in
Artificial Refugia
(C)
26
26
26
Natural
Refugia
Points
48
22
44
Average Temp.
When found in
Natural Refugia
(C)
28
29
28
P-Value
0.0171
2.2E-16
0.7085
51
Monty
30
28
26
22
24
Air Temperature C
32
34
p = 0.0171
Artificial
Natural
RefugiaClass
Figure 3.24 This figure displays Monty’s (male) preference for refugia type in relation to air
temperature. Natural refugia included mammal burrows. Artificial refugia included man-made
structures, pipes, rock piles, cover boards, and artificial burrows. The dark horizontal bars in this
figure represent the median. The boxes represent the 25th to 75th percentiles. The error bars
represent the 5th to 95th percentiles. Circles represent individual data points outside the 5th or 95th
percentiles. The P-value was calculated using a one-way permutation test.
52
Vader
28
26
24
20
22
Air Temperature C
30
32
p = 2.2e-16
Artificial
Natural
RefugiaClass
Figure 3.25 This figure displays Vader’s (male) preference for refugia type in relation to air
53
Nagini
25
20
Air Temperature C
30
35
p = 0.7085
Artificial
Natural
RefugiaClass
Figure 3.26 This figure displays Nagini’s (female) preference for refugia type in relation to air
54
Chapter 4
Discussion
Through this study I focused on the home range size, habitat use, activity patterns, and
refugia preferences of D. couperi in a fallow citrus grove in southeast Florida. During the course
of this study, a total of six adult snakes, four males and two females, were implanted with
transmitters. Of the six snakes captured, only five snakes could be tracked over an extended
period of time. Of these, four were located at least nine times during each of the NOAA seasons
allowing comparisons to be made between seasons. Three of the four snakes tracked through
both seasons were tracked for at least 307 days. The individuals tracked this length of time
included two adult males and one adult female. The small sample size for this study was due in
part to U.S. Fish Wildlife Services permitting restrictions, which limits the ability of this study to
provide population-level conclusions. However, the findings from this study do provide trends
that can be further tested in future studies.
Individuals in this study were tracked twice a week for 83 to 365 days. Total Home
range sizes for the four males varied from 23.52 – 65.78 ha and the only female tracked had a
home range of 9.71 ha. These home ranges are on the smaller end of the ranges recorded from
previous studies (Appendix Table 1). A radio telemetry study carried out in close proximity to
C-44 at Archbold Biological Station found average home ranges for males to be 74.3 ha and 18.6
ha for females (Layne and Steiner, 1996). The maximum recorded home range for males was
199.2 ha and 48.6 ha for females (Layne and Steiner, 1996). Layne and Steiner (1996) report
that these recorded ranges are likely smaller than the actual home ranges based on the correlation
they found between larger ranges with increased sampling. A study carried out recently in east-
55
central Florida included 107 snakes tracked once a week for 224 to 1,113 days. Home ranges
ranged from 12.8 - 538.4 ha and were calculated using minimum convex polygons (Breininger et
al., 2011). A recent study in Georgia tracked 32 snakes two to three times a week for 89 to 711
days. Home ranges ranged from 35 – 1,530 ha and were also calculated using minimum convex
polygons (Hyslop, 2007). The home range of 1,530 ha likely represents the largest recorded
snake home range in North America (Hyslop, 2007). Both of these studies had larger sample
sizes and tracked snakes over longer periods of time. Tracking frequency for this study was in
between referenced studies.
The smaller home ranges in this study could be a result of habitat quality, differential use
of habitat, and/or climate differences. The habitat at C-44 may represent a higher quality habitat
in relation to the needs of D. couperi compared to more natural habitats. The habitats used at
this site can be looked at as compressed in that it appears all of D. couperi’s requirements can be
found within a small area. This may allow for reduced home range sizes due to the closer
proximity of all necessary resources. The movements of a species and the area they occupy are
typically representative of the arrangement of necessary resources such as food, water, mates,
refugia, and appropriate thermal conditions (Gibbons and Semlitsch, 1987; Hyslop et al., 2009a).
Observations of prey items including small mammals and other snake species were frequently
seen at the field site indicating that prey items were prevalent. In addition both natural and
artificial refugia appeared to be abundant throughout canal and upland habitats. Water was also
abundant throughout the year although seasonal shifts caused the availability of water to decline
in upland habitats during the winter. Additionally, the climate of southeast Florida is warmer
and has less seasonal variation than that of previously referenced studies and may permit the
56
snakes to be more habitat generalists because of reduced restrictions on thermoregulation. This
may negate the need for individuals to increase their home range to include multiple habitats.
Both of the males tracked for more than 300 days had larger winter ranges than summer
ranges. Out of the three males with enough tracking events to create seasonal polygons, Paul was
the only male snake with a smaller winter range than summer range. Paul was predated 33 days
into the winter sampling period after having been located only nine times during the winter
season. It is possible that the small number of tracking events for this snake may have only
included part of his total home range and therefore underestimated its total size. The only female
tracked through both seasons showed a similar pattern to Paul in that she too had a larger
summer range than winter range. Females are undergoing gestation during much of the winter
and may not expand their range during this time (Hyslop, 2007).
Layne and Steiner (1996) found similar patterns at the Archbold Biological station for a
single male and female tracked long enough to make comparisons between seasons. A radiotracked male had a home range of 73 ha between the months of January and February and a
smaller home range of 42 ha in June and July. A radio-tracked female had a home range of 0.9
ha from January to March and a larger home range of 15 ha from April to May (Layne and
Steiner, 1996). Both of these snakes were sampled a minimal number of times but they represent
the closest study site nearest to ours at C-44, where D. couperi radio- tracking has occurred.
They also follow the same trends seen at C-44 in that the male had a larger winter range and
smaller summer range and the female had larger summer range and smaller winter range.
In Georgia populations Hyslop (2007) did not see any differences between seasonal home
range sizes in relation to sex, other than a reduction in spatial scale for female ranges throughout
the year. Any biological factors limiting female home range size during the winter in Georgia
57
would likely not be evident compared to males’ ranges because of the constraints on both sexes
from temperature. For this study it is possible that differences in seasonal home ranges between
sexes may simply be a result of small sample size.
D. couperi in Georgia were found to have larger summer ranges and smaller winter
ranges (Hyslop, 2007). Similarly a single D. couperi in central north Florida (Putnam County)
tracked over 323 days was also found to have a larger summer range and a smaller winter range
(Dodd and Barichivich, 2007). Colder temperatures restricted the movements of snakes in
Georgia and north Florida during winter so snakes spent more time in burrows. During the
warmer months snakes became more active and expanded their ranges to include different
habitats such as river bottoms and wetlands (Hyslop, 2007). The movement to new habitats may
have contributed to the much larger home ranges reported in these studies.
The geographical location of C-44 in southeast Florida provides a warmer climate with
mild winters. Because of the mild winters, D. couperi in the current study were not as restricted
by thermoregulation needs during the winter. This could contribute to larger winter home ranges
than those identified by Hyslop (2007). Studies tracking trans-located individuals in Georgia
showed temperature and seasonality are the two factors that most directly affected activity and
therefore home range size (Speake et al., 1978).
The larger winter home ranges compared to summer home ranges in the current study
may have been related to a smaller prey base and a reduced water supply during the winter.
During the winter water dries up across the landscape and likely restricts prey items to canals
that hold water all year long. Because of this water is a possible factor impacting changes in
home ranges between summer and winter at C-44. Based on the home ranges recorded in this
study it appears that as water dries up across the landscape during the winter, the snakes’ home
58
ranges increase to include a greater percentage of canal bank habitats. Similarly organisms that
constitute prey for D. couperi such as Banded Water Snakes (Nerodia fasciata) are likely
concentrated around the remaining water during the driest part of the year. On two occasions
during this study two different males were observed feeding on N. fasciata along canal banks.
Additionally the habitat preference findings in this study further support the importance of water
by showing that individuals spend a significant amount of time in canal habitats during the
winter. During the summer months this trend is not as strong with only Nagini and Vader
demonstrating a significant preference for canal habitat in relation to its availability. Seasonal
shifts in home range varied slightly among individuals but general trends become more evident
when examining individuals located over 300 days and when considering possible differences in
trends between sexes. The results of this study suggest trends in home range size for D. couperi
including: reduced summer season ranges: increased winter season ranges: and reduced total
home range size for individuals in southeast Florida at a fallow citrus grove.
The general habitat at C-44 is characterized as abandoned fallow citrus groves intersected
with irrigation canals. Abandoned citrus groves were listed as habitats commonly used by
foraging D. couperi at Archbold Biological Station (Layne and Steiner, 1996). Individuals
tracked in this study exclusively used this habitat and were never found outside of the citrus
groves. For this study the habitats at C-44 were divided into canal bank habitats and upland
habitats. Canal bank habitats consist of the canal itself as well as the surrounding embankment.
Upland habitats include fallow citrus groves bisected by swales and ditches that hold ephemeral
water during the summer. The preferences for canal banks versus uplands were examined
between seasons. Hyslop found that the most influential factor for microhabitat shifts is
59
seasonality (Hyslop et al., 2009a). They focused their microhabitat analysis around refugia
openings where snakes were located. Microhabitat was defined in regards to vegetation and
structure. They found that season rather than sex, size, or site played the biggest role in
determining what microhabitat snakes would use. Microhabitat analyses were not carried out for
this study but habitat preferences were analyzed in regards to available habitat and the amount of
time spent in these habitats during the winter and summer.
Rainfall and temperature are the major factors for distinguishing seasons in Florida
(NOAA, 2009). These factors cause seasonal changes in habitat and impact the activity patterns
of the snakes. Defining seasons in south Florida is a challenge. For this study, I used the
seasonal categories determined by NOAA, with a fixed date for the start and end of summer and
winter. Although the weather during the study period, January 2012 through March 2013, seem
to track well with the NOAA-defined seasons (Figure 2.3), it is possible that this seasonal
designation did not capture the seasons as perceived by the snakes, or their habit use in response
to the seasons. Some noticeable changes in the habitats during the summer season are the influx
of water and the explosion of vegetation. This affects both habitats. In the canal habitats the
canal bank is reduced during the summer because of the higher water levels. In the upland
habitats, ditches and other depressions fill with water. In addition, the growth of vegetation
provides cover for snakes to easily move across previously open fields. Movement across open
areas can be dangerous due to the risk of desiccation (Bogert et al., 1947) and predation. During
the winter season these ephemeral wet areas dried up. The canal water levels also dropped
exposing the banks and the cooler and drier weather results in a loss off much of the grassy
vegetation. By tracking snakes throughout the year it was possible to identify those areas where
60
the snakes were most commonly found which provided important information on habitat use and
seasonal preferences.
Identified seasonal home ranges indicate that the canals were an important habitat for D.
couperi during part of the year. Canals have also been documented as favorable habitat for D.
couperi in south Florida (Lawler, 1977). Lawler pointed to canals as likely places to locate this
species in south Florida and hypothesized that land crab burrows may provide refugia when G.
polyphemus burrows are not available. Studies in Everglades National Park have provided
anecdotal reports of D. couperi along canal banks in addition to agricultural fields and novel
habitats including mangrove swamps (Steiner et al., 1983).
All individuals tracked with the exception of Dagwood showed a significant preference
for canal habitats during the winter season. Within Dagwood’s range there was a ditch
intersection that held water throughout the winter. Dagwood spent a great deal of time along this
ditch. Despite the size of the ditch and the fact that it held water all year long it was not
classified as a canal. It is possible that this habitat served the same function as canal habitat.
Another trend indicated by my data was that all male snakes had a winter range with a
higher percentage of canal habitats than their summer range. Nagini, the only female in the
analysis, did not show this trend. She made extensive use of canal habitat throughout the year
and actually had the highest recorded percentage of canal habitat for any snake during the
summer. This follows trends noted by Hyslop (2007) where females and some males continued
to use habitat within their winter ranges all year long while other males only returned to over
wintering habitats during the winter months. The canals provided a reliable source of water
during the dry winter months and likely also an expanded prey base. In addition, the dry,
61
sparsely vegetated upland habitats likely contained fewer prey items and no cover. The lack of
cover may increase the likelihood of predation or desiccation.
During the summer months, the habitat preference for the male snakes switched to the
upland areas. This switch is likely driven by increased levels of precipitation, which increased
the distribution of water and caused an explosion of vegetation in the upland areas. In addition
the numerous swales and ditches bisecting the upland areas fill with water during the summer, so
the habitat was not exclusively typical upland. These flooded areas provided habitat for D.
couperi prey items. This was coupled with a reduced availability of foraging areas along the
canal banks as the water levels rose.
The use of canal habitat year round for Nagini and the use of canals primarily during the
winter for all males provides an alternative or contributing factor for why males may have visited
canal habitats with greater frequency during the winter. It is possible that canal habitats
represent a preferred habitat for female snakes and males enter these habitats for breeding
purposes. This fits trends of northern snakes during breeding season where males often
congregate around refugia being used by females (Stevenson et al., 2009). Previously
unidentified trends in habitat preferences and seasonal shifts for D. couperi include the
preference of canal habitat during the winter season by males and the possible yearlong
preference for canal habitats by females. These trends may be unique to southeast Florida
populations found in fallow citrus field habitats, and may help define alternative habitat to
include those areas with permanent water bodies.
Average distance moved between tracking events was used as an indicator of activity
level and patterns in this study. Using this method limits our ability to look at movements over a
62
short period of time and is only meaningful when used to gain a general pattern of activity. In
order to further refine activity levels using this method additional weekly sampling would be
necessary. By decreasing the number of days between sampling events you could analyze
activity on a finer scale. For this study, activity levels between NOAA seasons were compared.
The use of the NOAA defined seasons for the breakdown for this analysis may again possibly be
limiting as it breaks up the entire years worth of movements into two chunks that may or may not
capture what snakes are actually doing. An alternate way of determining seasons may have led
to different results regarding seasonal differences in activity. Because of this, activity patterns
were also compared across months to determine if analysis on a finer scale yielded any patterns
not evident between seasons.
Comparing trends in activity across different studies is difficult, as no standard for
quantifying activity exist. Moulis (1976) reported April as being the height of the active season
for D. couperi in Georgia, based on a nine-year monitoring study looking at the frequency of
sightings through the years. Another Georgia study using telemetry to track translocated
individuals found peak activity between the months of August and November based on
observations and shifts in home range sizes (Speake et al., 1978). A more recent telemetry study
looking at frequency of daily movements using the proportion of tracking days that an individual
changed locations found that females make smaller movements than males and that both sexes
make the fewest movements during the winter and the most during the summer (Hyslop, 2007).
A telemetry study that was conducted relatively close to C-44 in south-central Florida found that
the percentage of times snakes were recorded as active rather than inactive was highest from
August to October and then second highest from May to July (Layne and Steiner, 1996). Long
term monitoring in Everglades National Park shows peak activity based on frequency of
63
sightings between November and March (Steiner et al., 1983). It is possible that these findings
were skewed by the increased number of people making observations during those months.
Sightings at C-44 were also highest during the winter. Most individuals were captured during
this time although that could have been partially an artifact of the much lower levels of
vegetation present in the winter, making it easier to see and capture the snakes.
After analyzing all of the individuals’ activity patterns between seasons and months, none
of them showed a significant difference in their mean daily movements except for Nagini. Layne
and Steiner (1996) found similar trends in that females move much less during winter and spring
and more during summer and fall. Nagini’s height of activity (November) would have fallen into
Layne and Steiners’ fall season, and her lowest activity (December) would fall within their
winter season (Layne and Steiner, 1996). This trend is very weakly supported but, due to the
proximity of C-44 to Archbold Biological Station, it is plausible that individuals at both sites
may share similar activity trends. Although the male individuals at C-44 did not show a
significant difference, a constant pattern of higher mean activity in winter months was present
for sufficiently tracked individuals. In addition, home range sizes, a possible indirect measure of
activity, increased during the winter season. Activity levels are likely strongly impacted by
weather with snakes seeking refuge during the hottest periods in the summer and the coolest
periods in the winter but maintaining high activity levels throughout the year. Seasons in south
Florida are also tied to rainfall, which controls the distribution of moisture across the landscape.
The distribution of water is likely tied to both overall prey abundance, and the concentration of
potential prey items.
With the exception of Paul who had a small sample size, all males had significantly larger
ranges in the winter, but did not significantly increase their level of activity, as measured by
64
mean distance moved per day. The expanded winter ranges and slight trend in raised activity
through winter may have been contributed to by a reduction in prey availability in the cooler and
drier winter months as well as the need to include a reliable source of water. The larger ranges
and marginally increased activity in sufficiently tracked individuals could also be partially
caused by the males searching for females with which to breed.
What we do know about seasonal changes in activity patterns for this group of snakes is
that both male and female snakes remain active all year long with peak activity months falling in
the winter season for both sexes. These trends differ from those expressed by snakes in Georgia
(Hyslop, 2007). This is likely due to the cooler climate in Georgia restricting activity during the
winter. In addition the reduction of vegetation, the preference for canal banks, and the slightly
raised activity levels make the winter season the most likely time to see D. couperi. This may
also be the most dangerous time of year for D. couperi. Three out of the four snakes that were
predated during this study were predated during the winter. The additional snake was likely
killed in an intra-species conflict while expanding his home range.
Refugia type and availability may also play a role in where individuals are found during
certain times of the year. In Georgia, Hyslop (2007) found that D. couperi show a preference for
G. polyphemus burrows during the winter. These burrows are typically found in sandhill
environments and may represent the main draw for D. couperi to these habitats. In a southcentral Florida telemetry study G. polyphemus burrows represented 62% of refugia used (Layne
and Steiner, 1996). Natural ground holes and burrows of unknown origin accounted for another
25% of the refugia used (J. Layne & Steiner, 1996). No preference existed for refugia type in
relation to sex, activity, or season (Layne and Steiner, 1996). Additionally Layne and Steiner
65
(1996) observed D. couperi using a house, barn and concrete culverts as refugia during dry
weather. For this study, records were kept on the type and location of refugia used and
comparisons made between refugia preference in the two NOAA seasons. Only snakes tracked
for at least 300 days were included in this analysis. While snakes remained active throughout the
year, refugia were needed for resting, protection from predators, and protection during extremely
cool and hot periods.
Snakes were frequently observed using refugia along canal banks during the winter
months. It was also interesting that many of the refugia used were structures or items that were
left over from the citrus operations. Items like pipes, concrete piles, and even a septic system
were used as refugia during the winter. Many of the available artificial refugia were located
along canal banks. The snakes may have showed a preference for artificial refugia during the
winter because of the insulation some of the artificial items may offer, or simply due to its
availability in the canal habitats that the snakes preferred during winter.
It is possible that Nagini’s sex plays a role in her refugia preferences. Female D. couperi
may show preferences for refugia use based on quality of refugia in relation to nest site locations.
A study looking at translocated females tracked in north Florida showed that gestating females
show a preference for inactive G. polyphemus burrows (Hyslop et al., 2009a). This preference is
possibly due to the risk of eggs in active burrows being destroyed by other burrow denizens.
Factors such as this could skew any correlation between refugia type and air temperature. Nagini
also had fewer winter tracking events because her signal could not be located on multiple
occasions. It is probable that she was in a burrow that was sufficiently deep or insulated to
completely block her signal. This likely skewed our analysis of burrow preferences for Nagini.
Overall we see a trend for male snakes using artificial refugia in cooler weather and natural
66
refugia in warmer weather. Nagini showed no significant preference for certain refugia types in
relation to air temperature but her results were complicated by our inability to track her on a
number of sampling days. Despite this, the average temperature when Nagini was observed
using artificial refugia was identical to the average temperatures recorded when the other snakes
used artificial refugia. Based on these preferences for refugia types in relation to air
temperatures, it is plausible that there may be differences in how much insulation a particular
type of refugia may offer. Additional snakes need to be tracked and burrow temperatures
measured to determine whether this is the case. We now know that D. couperi at C-44 are not
dependent on G. polyphemus burrows during any part of the year and that they will use human
artifacts as refugia.
Conclusions
D. couperi using the C-44 reservoir site demonstrate trends in home range size, habitat
use, seasonal activity patterns, and seasonal refugia preferences that differ from other
populations of this species. Driving factors for these differences seem to be linked primarily to
differences in hydro period and climate. Some of the objectives of this study highlight
differences between the individuals tracked during this study and northern populations sampled
in previous studies.
One notable trend is the difference in sizes between seasonal ranges. The largest
seasonal range for males tracked for a full year at C-44 was winter. Winter represents the
smallest seasonal range for northern populations of D. couperi (Hyslop, 2007). Another
difference is habitat preferences. The individuals tracked during this study were tracked over a
highly disturbed landscape. The available habitat is much different than that of more northern
populations, and of the often-assumed need for pristine upland habitat for this species.
67
Availability of water appeared to be a significant factor in changes in home ranges observed over
the course of the study. Seasonal activity patterns of the snakes in the current study also differed
from those in other studies. Males tracked in this study showed no significant difference in
activity across seasons. This differs from northern populations and is likely caused by the cooler
temperatures and the resulting decrease in winter activity in northern D. couperi (Hyslop, 2007).
A final difference is the use of refugia. The C-44 site is unusual in that there are no G.
polyphemus present on site. The burrows of these tortoises were important refugia for northern
populations during the winter (Hyslop, 2007). The individuals tracked for this study relied
heavily on artificial refugia during the winter although natural refugia were available.
Future studies aimed at elucidating basic life history of D. couperi in unique habitats
should focus on prey base, a site-specific reproductive timeline, role of refugia, and causes of
mortality in novel environments. Understanding and quantifying prey base is important in
understanding the basic life history of an organism. The availability, type, and location of prey
likely play a role in the activity and home range size of a predator. Site-specific reproductive
timelines are also important in understanding the activity patterns and movements of an
organism, particularly for D. couperi who appears to shows varied reproductive timelines
throughout its range. Understanding the role certain refugia play is also important for D.
couperi. The availability of refugia may be a limiting factor for more northern snakes,
particularly if G. polyphemus burrows are not present. The final recommendation is to quantify
dangers to this species in novel sites. During the course of this study four of the snakes being
tracked were lost to mortality. Two of these snakes appear to have been predated by feral hogs
(Sus scrofa). Determining if S. scrofa is a significant predator of D. couperi is important in
developing land practices aimed at the continued survival of this species. These objectives cover
68
important basic life history traits that would be seminal in the development of conservation
efforts and land practices that cater to D. couperi in disturbed landscapes.
Some important findings from this study that impact management of the Indigo Snake
are its ability to populate and thrive in highly disturbed habitats and to make use of artificial
burrows. The smaller home ranges of the C-44 snakes may indicate that the habitat was quite
suitable and that snakes were not forced to travel long distances for adequate food, water, and
shelter. The small ranges may also have been partially a result of a relatively high density of
snakes. From a survey and monitoring perspective, the snakes were not always easy to find.
Sixty seven percent of the time we were tracking individuals we never actually saw the snake,
despite receiving a strong radio signal indicating the snake was likely within a few feet of us.
Additionally we were unable to locate individuals that were being tracked 11% of the time even
when we knew the snakes were somewhere in the area. This difficulty in finding the snake, and
the recognition that D. couperi can thrive in some heavily disturbed habitats, should result in
very conservative conclusions regarding the absence of snakes from a potential development site
when the survey includes only limited visual inspection.
Findings also demonstrated important differences between this population and other
populations, especially more northern populations. These differences highlight the need for
conservation biologists to consider ecological and behavioral differences across the range of a
species when developing management plans. The fact that this study documented a population
of D. couperi apparently thriving on an extremely impacted site, should not guide us toward
believing the snake is no longer in danger from habitat loss. While the C-44 site appears to be
good habitat; this tells us nothing about other human impacted landscapes.
69
However, in a world were landscape alteration is common practice, it is important to
understand that altered habitat can substitute for more natural habitats for many organisms.
Understanding the role of disturbed habitats as acceptable habitat for endangered and threatened
species and species of special concern is integral to their continued survival. Learning how to
effectively improve these atypical habitats for use by keystone species and others, allows us to
conserve natural flora and fauna in habitats that are becoming more common as human
populations increase, hopefully positively affecting the trend in global biodiversity loss.
70
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Speake, D.W., J. Diemer, & J. McGlincy (1981a). Eastern indigo snake recovery plan: U.S. Fish
and Wildlife Service, Atlanta, Georgia.
Speake, D.W., J.A. McGlincy, & T.R. Colvin (1981b). Response of eastern indigo snakes to
gassing their dens. Paper presented at the Proceedings of the annual conference of the
southeastern association of fish and wildlife agencies. 35. 135-138.
Steiner, T.M., J.A. Kushlan, & O.L. Bass (1983). Status of the eastern indigo snake in southern
Florida National Parks and vicinity: National Park Service, South Florida Research
Center, Everglades National Park.
Stevenson, D.J., M.R. Bolt, D.J. Smith, K.M. Enge, N.L. Hyslop, T.M. Norton, & K.J. Dyer
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74
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75
Appendix
Appendix Table 1
Home range comparison table
Study Location
Average
Male Home
Range Size
Male
Sample
Size
Average
Female
Home Range
Size
Female
Sample
Size
Tracking
Duration
(Days)
Sampling
Frequency
C-44 (Martin County)
42.8
4
9.71
1
83-365
Twice a Week
74.3
12
18.6
7
8-197
Daily
118
31
41
18
Unknown
Unknown
Bolt, 2006
141
4
-
-
Unknown
Unknown
Moler 1985
201.7
23
75.6
21
224-1,113
Once a week
Breininger et
al., 2011
538
24
126
14
89- 711
Three times a
week
Hyslop, 2007
Central Florida (Highlands
County)
Southeastern Florida
(Brevard County)
North Florida (Levy
County)
Central Florida
(Highlands, Polk
Counties)/ Southeastern
Florida (Brevard County)
Southeastern Georgia (Fort
Stewart Military
Reservation)
Study
Authors
Current
Study
Layne and
Steiner, 1996
This table shows the results of D. couperi home range studies using radio-telemetry. All home range sizes were calculated using
100% minimum convex polygons or minimum bounding geometry.
76
Appendix Table 2
Raw Data
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Vader(Capture)
Vader(Release)
Vader 1
Vader 2
Vader 3
Vader 4
Vader 5
Vader 6
Vader 7
Vader 8
Vader 9
Vader 10
Vader 11
Vader 12
Vader 13
Vader 14
Vader 15
Vader 16
Vader 17
Vader 18
Vader 19
Vader 20
Vader 21
Vader 22
Vader 23
Vader 24
Vader 25
Vader 26
Vader 27
Vader 28
Vader 29
Vader 30
Vader 31
1/19/12
2/16/12
2/17/12
2/17/12
2/21/12
2/21/12
2/23/12
2/23/12
2/24/12
2/24/12
2/28/12
2/28/12
3/1/12
3/1/12
3/2/12
3/2/12
3/6/12
3/6/12
3/8/12
3/8/12
3/9/12
3/9/12
3/13/12
3/13/12
3/15/12
3/15/12
3/20/12
3/20/12
3/22/12
3/22/12
3/28/12
3/28/12
3/30/12
12:00
14:30
10:52
14:15
11:30
15:30
11:53
15:46
12:34
15:17
12:17
14:14
12:18
14:06
12:54
14:48
11:27
13:17
11:50
15:00
12:52
14:58
12:33
14:02
12:22
13:30
13:10
14:41
13:01
14:00
11:30
13:45
12:55
17
27
24
24
24
24
26
26
29
29
23
23
27
27
28
28
24
24
24
24
27
27
25
25
27
27
25
25
27
27
26
26
27
1
2
2
2
2
2
1
1
2
2
3
3
3
3
2
2
2
3
3
3
3
3
3
3
3
3
2
2
2
2
2
2
2
27.09267
27.09270
27.09977
27.10070
27.09920
27.10103
27.09938
27.09652
27.09533
27.09267
27.09267
27.09267
27.09267
27.09267
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09273
27.09260
27.09260
27.09800
27.09740
27.09652
-80.44952
-80.44960
-80.45052
-80.45115
-80.45277
-80.45330
-80.45197
-80.45232
-80.45252
-80.44990
-80.44988
-80.44988
-80.44988
-80.44988
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44968
-80.44985
-80.44985
-80.45253
-80.45322
-80.45222
3
1
1
1
2
2
2
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
X
4
X
X
X
X
X
X
4
X
5
5
5
5
4
4
4
4
4
4
4
4
4
4
4
4
4
4
5
5
3
X
2
Above
Ground
1
2
1
1
1
1
1
1
2
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
2
Burrow
0
2
0
0
0
0
0
0
2
0
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
0
1
77
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Vader 32
Vader 33
Vader 34
Vader 35
Vader 36
Vader 37
Vader 38
Vader 39
Vader 40
Vader 41
Vader 42
Vader 43
Vader 44
Vader 45
Vader 46
Vader 47
Vader 48
Vader 49
Vader 50
Vader 51
Vader 52
Vader 53
Vader 54
Vader 55
Vader 56
Vader 57
Vader 58
Vader 59
Vader 60
Vader 61
Vader 62
Vader 63
Vader 64
Vader 65
4/3/12
4/6/12
4/6/12
4/10/12
4/13/12
4/13/12
4/17/12
4/19/12
4/24/12
4/26/12
5/1/12
5/4/12
5/7/12
5/11/12
5/11/12
5/15/12
5/17/12
5/22/12
5/25/12
5/29/12
6/1/12
6/5/12
6/8/12
6/12/12
6/15/12
6/19/12
6/21/12
6/21/12
6/21/12
6/26/12
6/28/12
7/3/12
7/6/12
7/10/12
12:39
13:04
14:22
13:31
13:39
15:07
13:18
13:42
11:45
13:08
15:00
12:20
12:25
8:05
11:25
12:27
15:58
11:39
13:04
14:01
10:12
13:19
13:16
12:56
X
X
22:30
1:32
5:07
12:55
11:33
14:14
13:02
13:26
29
29
29
27
27
27
27
28
19
27
27
30
33
26
26
29
28
29
30
30
25
30
27
28
29
29
27
26
26
31
28
32
36
32
1
2
2
2
2
2
3
2
1
2
3
2
2
2
2
2
3
2
2
3
3
3
3
1
2
3
2
2
2
3
1
3
3
2
27.09922
27.10113
27.10113
27.09918
27.09648
27.09648
27.09587
27.09587
27.09587
27.09587
27.09835
27.09950
27.09953
27.09885
27.09888
27.10055
27.09937
27.09923
27.09920
27.09920
27.10035
27.10080
27.09918
27.10065
X
X
27.09590
27.09590
27.09590
27.09592
27.09973
27.10082
27.10097
27.09992
-80.45048
-80.45373
-80.45373
-80.45050
-80.45222
-80.45222
-80.45267
-80.45267
-80.45255
-80.45255
-80.45373
-80.45602
-80.45575
-80.45372
-80.45375
-80.45620
-80.45512
-80.45050
-80.45050
-80.45050
-80.45598
-80.45312
-80.45292
-80.45617
X
X
-80.45258
-80.45258
-80.45258
-80.45262
-80.45375
-80.45397
-80.45370
-80.45337
1
1
1
1
3
3
4
4
4
4
2
1
1
1
1
1
1
1
1
1
2
1
1
1
X
X
4
4
4
4
1
2
1
1
2
X
X
2
2
2
4
4
4
4
X
2
2
2
X
2
X
2
2
2
2
X
2
2
X
X
4
4
4
4
2
2
X
2
Above
Ground
2
X
X
2
2
2
2
2
2
2
X
2
2
2
1
2
1
2
2
2
2
1
2
2
X
X
2
2
2
2
2
2
X
2
Burrow
1
X
X
1
1
1
X
X
X
X
X
1
1
1
0
1
0
1
1
1
1
X
1
1
X
X
2
2
2
2
1
1
X
1
78
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Vader 66
Vader 67
Vader 68
Vader 69
Vader 70
Vader 71
Vader 72
Vader 73
Vader 74
Vader 75
Vader 76
Vader 77
Vader 78
Vader 79
Vader 80
Vader 81
Vader 82
Vader 83
Vader 84
Vader 85
Vader 86
Vader 87
Vader 88
Vader 89
Vader 90
Vader 91
Vader 92
Vader 93
Vader 94
Vader 95
Vader 96
Vader 97
Vader 98
Vader 99
7/13/12
7/16/12
7/26/12
7/30/12
7/31/12
8/3/12
8/11/12
8/14/12
8/17/12
8/21/12
8/24/12
8/28/12
8/31/12
9/4/12
9/7/12
9/11/12
9/14/12
9/18/12
9/21/12
9/25/12
9/28/12
10/2/12
10/5/12
10/9/12
10/13/12
10/16/12
10/19/12
10/24/12
10/30/12
11/2/12
11/6/12
11/9/12
11/11/12
11/16/12
13:05
12:35
11:40
19:00
9:05
8:50
8:02
9:50
X
X
9:04
13:00
10:20
12:26
10:50
10:15
11:40
9:35
12:21
12:45
11:42
8:30
12:00
12:40
11:15
14:49
11:25
10:15
16:50
10:30
13:30
15:50
12:50
14:30
30
26
30
29
27
29
27
31
32
29
29
30
31
29
30
29
29
26
30
28
30
24
31
30
29
29
33
30
24
24
27
25
27
24
2
3
2
3
1
2
3
2
2
2
2
2
2
2
2
2
4
2
3
3
2
3
2
2
2
2
1
2
1
1
2
2
2
3
27.10038
27.09627
27.09974
X
27.10019
X
27.10008
X
X
X
27.09631
27.10099
27.09909
27.10104
27.09909
27.09652
27.09652
27.09650
27.09725
27.10002
27.10036
27.09899
27.09984
27.09653
X
27.09591
27.09651
27.09970
X
27.09585
27.09800
X
27.09611
27.09643
-80.45598
-80.45252
-80.45375
X
-80.45645
X
-80.45340
X
X
X
-80.45245
-80.45363
-80.45173
-80.45139
-80.45194
-80.45247
-80.45247
-80.45245
-80.45342
-80.45236
-80.45615
-80.44998
-80.45222
-80.45237
X
-80.45270
-80.45235
-80.45448
X
-80.45226
-80.45083
X
-80.45266
-80.45264
2
4
1
X
1
X
1
X
X
X
3
X
2
1
2
3
3
3
1
1
2
1
1
3
X
4
3
1
X
4
1
X
4
3
2
4
2
X
X
X
X
X
X
X
4
X
X
2
X
X
4
4
X
X
2
X
X
X
X
4
X
X
X
4
X
X
4
X
Above
Ground
2
2
2
X
1
X
1
X
X
X
2
X
1
2
1
1
2
2
1
1
2
1
1
X
X
2
1
1
X
2
1
X
2
1
Burrow
1
2
1
X
0
X
0
X
X
X
2
X
X
1
0
0
2
2
0
0
1
0
0
0
X
2
X
0
X
2
0
X
2
0
79
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Vader 100
Vader 101
Vader 102
Vader 103
Vader 104
Vader 105
Vader 106
Vader 107
Vader 108(Dead)
Monty(Capture)
Monty(Release)
Monty 1
Monty 2
Monty 3
Monty 4
Monty 5
Monty 6
Monty 7
Monty 8
Monty 9
Monty 10
Monty 11
Monty 12
Monty 13
Monty 14
Monty 15
Monty 16
Monty 17
Monty 18
Monty 19
Monty 20
Monty 21
Monty 22
Monty 23
11/20/12
11/24/12
11/27/12
11/30/12
12/2/12
12/5/12
12/11/12
12/14/12
12/18/12
1/10/12
2/7/12
2/7/12
2/9/12
2/9/12
2/14/12
2/16/12
2/17/12
2/21/12
2/23/12
2/24/12
2/24/12
2/28/12
2/28/12
3/1/12
3/1/12
3/2/12
3/2/12
3/6/12
3/6/12
3/8/12
3/9/12
3/13/12
3/13/12
3/15/12
14:49
18:15
14:15
11:40
14:40
12:00
11:41
16:05
13:00
11:00
11:55
13:30
12:40
14:47
13:20
X
X
X
X
13:10
15:30
12:37
14:07
11:04
13:40
12:42
14:40
11:15
12:47
11:10
12:40
12:22
13:45
12:30
23
21
25
24
22
24
22
24
32
18
27
27
24
24
24
27
24
24
26
29
29
23
23
26
26
28
28
24
24
24
27
25
25
26
2
2
3
2
3
3
4
2
1
2
3
3
3
3
2
2
2
2
1
2
2
3
3
3
3
2
2
2
3
3
3
3
3
3
27.09306
X
27.09612
27.09610
X
27.10178
27.09240
27.09566
27.09507
27.09263
27.09263
27.09263
27.09322
27.09345
27.09043
X
X
X
X
27.09058
27.09058
27.09057
27.09057
27.09057
27.09057
27.09057
27.09057
27.09057
27.09057
27.09057
27.09043
27.09555
27.09613
27.09383
-80.44984
X
-80.45272
-80.45239
X
-80.45070
-80.44976
-80.45255
-80.45444
-80.44990
-80.44990
-80.44990
-80.44770
-80.44847
-80.44953
X
X
X
X
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44935
-80.44932
-80.44928
-80.44932
-80.44933
1
X
4
4
X
1
1
1
2
1
1
1
1
1
3
X
X
X
X
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
X
X
4
4
X
X
X
X
X
X
X
5
X
X
3
X
X
X
X
3
3
3
3
3
3
3
3
3
3
3
3
X
X
2
Above
Ground
1
X
2
2
X
1
1
1
1
1
1
2
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
2
Burrow
0
X
2
2
X
0
0
0
0
0
0
2
0
0
2
X
X
X
X
2
2
2
2
2
2
2
2
2
2
2
2
0
0
1
80
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Monty 24
Monty 25
Monty 26
Monty 27
Monty 28
Monty 29
Monty 30
Monty 31
Monty 32
Monty 33
Monty 34
Monty 35
Monty 36
Monty 37
Monty 38
Monty 39
Monty 40
Monty 41
Monty 42
Monty 43
Monty 44
Monty 45
Monty 46
Monty 47
Monty 48
Monty 49
Monty 50
Monty 51
Monty 52
Monty 53
Monty 54
Monty 55
Monty 56
Monty 57
3/15/12
3/20/12
3/22/12
3/22/12
3/28/12
3/28/12
3/30/12
4/3/12
4/6/12
4/10/12
4/13/12
4/17/12
4/17/12
4/19/12
4/24/12
4/26/12
5/1/12
5/4/12
5/7/12
5/11/12
5/11/12
5/15/12
5/17/12
5/22/12
5/25/12
5/29/12
6/1/12
6/5/12
6/8/12
6/12/12
6/15/12
6/19/12
6/21/12
6/26/12
1:49
12:40
12:50
13:54
13:16
14:00
11:20
12:03
12:30
12:59
X
12:28
14:49
12:45
15:47
X
X
X
X
7:15
11:00
13:11
15:37
12:23
12:46
13:39
9:51
12:58
12:51
12:18
12:21
12:05
11:06
12:05
26
27
27
27
26
26
24
29
29
27
27
27
27
28
22
27
27
30
33
24
24
29
28
29
30
30
24
30
28
29
29
29
26
29
3
2
2
2
2
2
2
1
2
2
2
3
3
3
1
2
3
2
2
2
2
2
3
3
2
3
3
3
3
1
2
3
2
3
27.09383
27.09743
27.09707
27.09707
27.09707
27.09707
27.09707
X
X
27.09707
X
27.09585
27.09588
27.09707
27.09707
X
X
X
X
27.09465
27.09470
27.09170
27.08947
27.08998
27.08998
27.08960
27.09067
27.09067
27.09067
27.08948
27.08958
27.08975
27.08975
27.09010
-80.44933
-80.44943
-80.44930
-80.44930
-80.44930
-80.44930
-80.44930
X
X
-80.44930
X
-80.44907
-80.44933
-80.44930
-80.44930
X
X
X
X
-80.44905
-80.44912
-80.44898
-80.44877
-80.44722
-80.44722
-80.44713
-80.44713
-80.44713
-80.44713
-80.44642
-80.44888
-80.44687
-80.44687
-80.44672
3
3
3
3
3
3
3
X
X
3
X
1
3
X
3
X
X
X
X
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
X
3
3
3
3
3
X
X
3
X
X
X
X
3
X
X
X
X
X
2
X
X
2
2
2
2
2
2
2
2
2
2
X
Above
Ground
2
1
2
2
2
2
2
X
X
2
X
1
1
X
2
X
X
X
X
1
2
1
1
2
2
2
2
2
2
2
2
2
2
1
Burrow
1
0
2
2
2
2
2
X
X
2
X
0
0
X
2
X
X
X
X
0
1
0
0
1
1
1
1
1
1
1
1
1
1
X
81
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Monty 58
Monty 59
Monty 60
Monty 61
Monty 62
Monty 63
Monty 64
Monty 65
Monty 66
Monty 67
Monty 68
Monty 69
Monty 70
Monty 71
Monty 72
Monty 73
Monty 74
Monty 75
Monty 76
Monty 77
Monty 78
Monty 79
Monty 80
Monty 81
Monty 82
Monty 83
Monty 84
Monty 85
Monty 86
Monty 87
Monty 88
Monty 89
Monty 90
Monty 91
6/28/12
7/3/12
7/6/12
7/10/12
7/13/12
7/16/12
7/26/12
7/26/12
7/30/12
7/31/12
8/3/12
8/11/12
8/14/12
8/17/12
8/21/12
8/24/12
8/28/12
8/31/12
9/4/12
9/7/12
9/11/12
9/14/12
9/18/12
9/18/12
9/21/12
9/25/12
9/28/12
10/2/12
10/5/12
10/9/12
10/13/12
10/16/12
10/19/12
10/24/12
12:24
13:03
12:30
12:17
12:31
9:54
10:27
14:22
18:09
8:20
9:18
X
9:35
10:51
11:47
9:31
12:00
10:42
13:10
11:15
9:40
10:38
8:30
10:45
13:00
13:25
12:36
8:50
12:19
13:05
10:35
15:17
9:15
10:40
28
32
33
33
30
27
29
27
30
24
29
27
31
32
29
29
29
31
29
30
25
28
25
25
30
29
31
24
31
29
29
29
26
35
1
2
3
3
2
3
2
1
2
1
2
3
1
2
2
2
2
2
3
2
1
2
1
1
3
2
2
3
2
2
2
2
1
2
27.09343
27.09402
27.09402
27.08958
27.08907
27.08985
27.09464
27.09466
27.09462
27.09462
27.09513
X
27.09375
27.09142
27.08939
27.09333
27.09246
27.09246
27.09464
27.09419
27.09069
27.08976
27.09070
27.09042
X
27.09243
27.09243
27.09029
27.09368
27.09335
27.09438
27.09214
27.09419
27.09419
-80.44673
-80.44835
-80.44835
-80.44662
-80.44877
-80.44852
-80.44669
-80.44670
-80.44669
-80.44669
-80.44589
X
-80.44535
-80.44671
-80.44676
-80.44632
-80.44717
-80.44717
-80.44669
-80.44794
-80.44889
-80.44634
-80.44888
-80.44874
X
-80.44715
-80.44715
-80.44866
-80.44903
-80.44900
-80.44677
-80.44894
-80.44795
-80.44796
1
1
1
1
3
1
3
1
1
1
2
X
1
1
2
2
1
1
1
1
1
1
1
1
X
1
1
1
1
1
1
1
1
1
2
2
2
2
2
X
2
2
2
2
X
X
X
2
X
X
2
2
2
2
2
X
2
X
X
2
2
X
X
X
X
X
2
2
Above
Ground
2
2
2
2
2
1
2
2
2
2
1
X
1
2
1
1
2
2
2
2
2
1
2
1
X
2
2
1
1
1
1
1
2
2
Burrow
1
1
1
1
1
0
1
1
1
1
0
X
0
1
0
0
1
1
1
1
1
0
1
0
X
1
1
0
0
0
0
0
1
1
82
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Monty 92
Monty 93
Monty 94
Monty 95
Monty 96
Monty 97
Monty 98
Monty 99
Monty 100
Monty 101
Monty 102
Monty 103
Monty 104
Monty 105
Monty 106
Monty 107
Monty 108
Monty 109
Monty 110
Monty 111
Monty 112
Monty 113
Monty 114
Monty 115
Monty 116
Monty 117
Monty 118
Monty 119
Nagini(Capture)
Nagini(Release)
Nagini 1
Nagini 2
Nagini 3
Nagini 4
10/24/12
10/30/12
11/2/12
11/6/12
11/9/12
11/11/12
11/16/12
11/20/12
11/24/12
11/27/12
11/30/12
12/2/12
12/5/12
12/11/12
12/14/12
12/18/12
12/21/12
12/25/12
12/28/12
12/31/12
1/5/13
1/7/13
1/9/13
1/14/13
1/18/13
1/23/13
1/25/13
1/29/13
2/23/12
3/30/12
3/30/12
4/3/12
4/6/12
4/6/12
11:50
16:50
11:30
14:00
13:50
12:15
15:00
14:31
18:43
12:30
10:45
13:45
12:30
11:22
15:26
13:35
11:40
15:45
12:30
14:15
12:26
15:20
13:30
13:10
14:20
12:45
12:35
10:15
10:35
11:07
13:15
12:20
12:40
14:13
35
24
26
27
25
26
21
23
21
28
24
22
25
27
24
32
18
27
23
26
27
24
29
29
23
25
21
22
26
24
24
29
29
29
2
1
1
2
2
2
3
2
2
3
3
3
2
4
2
1
1
3
1
2
3
4
2
2
2
2
1
2
1
2
2
1
2
2
27.09419
X
27.08920
27.09003
27.08684
27.08712
27.09349
27.09104
27.09182
27.09182
27.09180
27.09179
27.09181
27.08955
27.08923
27.08925
27.08734
27.08809
27.08677
27.08789
27.08808
27.08687
27.08691
27.08767
27.09182
27.09184
27.09182
27.09201
27.11065
27.11065
27.11065
27.11097
27.11097
27.11097
-80.44796
X
-80.44618
-80.44386
-80.44764
-80.44761
-80.44743
-80.45184
-80.44985
-80.44982
-80.44984
-80.44984
-80.44982
-80.45299
-80.45039
-80.44650
-80.44597
-80.44893
-80.44734
-80.45084
-80.44937
-80.44636
-80.44634
-80.45098
-80.44984
-80.44982
-80.44983
-80.44632
-80.44915
-80.44915
-80.44915
-80.44838
-80.44838
-80.44838
1
X
3
1
1
1
2
1
1
1
1
1
1
1
3
3
1
1
1
1
3
1
1
1
1
1
1
1
3
3
3
3
3
3
2
X
X
2
2
2
X
X
2
2
2
2
2
X
2
X
X
X
X
X
2
X
2
2
2
2
2
X
X
3
3
2
2
2
Above
Ground
2
X
1
2
2
2
1
1
2
2
2
2
2
1
2
1
1
1
1
1
2
1
2
2
2
2
2
1
1
2
2
2
2
2
Burrow
1
X
0
1
1
1
0
0
1
1
1
1
1
0
1
0
0
0
0
0
1
0
1
1
1
1
1
0
X
2
2
1
1
1
83
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Nagini 5
Nagini 6
Nagini 7
Nagini 8
Nagini 9
Nagini 10
Nagini 11
Nagini 12
Nagini 13
Nagini 14
Nagini 15
Nagini 16
Nagini 17
Nagini 18
Nagini 19
Nagini 20
Nagini 21
Nagini 22
Nagini 23
Nagini 24
Nagini 25
Nagini 26
Nagini 27
Nagini 28
Nagini 29
Nagini 30
Nagini 31
Nagini 32
Nagini 33
Nagini 34
Nagini 35
Nagini 36
Nagini 37
Nagini 38
4/10/12
4/13/12
4/17/12
4/19/12
4/24/12
4/26/12
5/1/12
5/4/12
5/4/12
5/7/12
5/11/12
5/15/12
5/17/12
5/22/12
5/25/12
5/29/12
6/1/12
6/5/12
6/8/12
6/12/12
6/15/12
6/19/12
6/21/12
6/21/12
6/21/12
6/26/12
6/28/12
7/3/12
7/6/12
7/10/12
7/13/12
7/16/12
7/26/12
7/30/12
13:15
14:01
13:44
14:06
10:57
12:53
12:28
12:50
14:10
X
X
12:45
16:11
14:07
13:42
14:15
10:36
13:30
X
X
X
13:11
21:16
0:42
4:20
13:27
10:33
13:56
13:38
14:27
14:18
10:57
X
19:20
27
27
27
28
16
27
27
30
30
33
26
29
28
29
30
30
25
30
28
29
29
29
27
26
26
31
27
32
33
33
30
27
30
27
2
2
3
3
1
1
3
2
2
2
2
2
3
2
2
3
3
3
3
1
2
3
3
3
3
3
1
3
3
2
2
3
2
2
27.11103
27.11102
27.11097
27.11097
27.11097
27.11097
27.11335
27.11315
27.11198
X
X
27.11260
27.11247
27.11343
27.11442
27.11152
27.11045
27.11343
X
X
X
27.11342
27.11103
27.11103
27.11103
27.11103
27.11103
27.11103
27.11433
27.11453
27.11145
27.11350
X
X
-80.44915
-80.44902
-80.44848
-80.44848
-80.44848
-80.44848
-80.44837
-80.44892
-80.44873
X
X
-80.44897
-80.44915
-80.44840
-80.44750
-80.44830
-80.44890
-80.44842
X
X
X
-80.44840
-80.44903
-80.44903
-80.44903
-80.44903
-80.44903
-80.44903
-80.44758
-80.44883
-80.44933
-80.44932
X
X
3
3
3
3
3
3
1
X
1
X
X
1
3
2
1
X
2
2
X
X
X
2
3
3
3
3
3
3
1
1
3
3
X
X
4
4
2
2
2
2
X
2
X
X
X
X
X
2
X
X
2
2
X
X
X
2
4
4
4
4
4
4
2
X
2
X
X
X
Above
Ground
2
2
2
2
2
2
1
2
1
X
X
1
1
2
X
X
2
2
X
X
X
2
2
2
2
2
2
2
2
1
2
1
X
X
Burrow
2
2
1
1
1
1
X
1
X
X
X
X
X
1
1
X
1
1
X
X
X
1
2
2
2
2
2
2
1
X
1
X
X
X
84
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Nagini 39
Nagini 40
Nagini 41
Nagini 42
Nagini 43
Nagini 44
Nagini 45
Nagini 46
Nagini 47
Nagini 48
Nagini 49
Nagini 50
Nagini 51
Nagini 52
Nagini 53
Nagini 54
Nagini 55
Nagini 56
Nagini 57
Nagini 58
Nagini 59
Nagini 60
Nagini 61
Nagini 62
Nagini 63
Nagini 64
Nagini 65
Nagini 66
Nagini 67
Nagini 68
Nagini 69
Nagini 70
Nagini 71
Nagini 72
7/31/12
7/31/12
8/3/12
8/11/12
8/14/12
8/17/12
8/21/12
8/24/12
8/28/12
8/31/12
9/4/12
9/7/12
9/11/12
9/11/12
9/14/12
9/18/12
9/18/12
9/21/12
9/25/12
9/28/12
10/2/12
10/5/12
10/9/12
10/13/12
10/16/12
10/19/12
10/24/12
10/24/12
10/30/12
11/2/12
11/6/12
11/9/12
11/11/12
11/16/12
8:00
9:35
8:31
X
10:10
9:31
10:32
10:47
11:17
10:00
11:51
10:19
8:45
11:00
9:47
7:50
11:00
11:35
11:38
11:12
8:00
11:33
12:04
11:50
14:20
8:20
9:45
12:15
15:23
9:45
13:00
13:05
11:10
13:07
23
23
27
27
32
29
29
34
29
28
29
29
25
25
28
24
24
31
29
30
24
32
29
29
31
25
27
36
21
20
27
28
26
24
1
1
2
3
2
2
2
2
3
2
2
2
1
1
2
1
1
3
3
2
3
2
2
2
2
1
2
2
1
1
2
2
2
3
27.11296
27.11400
27.11468
X
27.11448
27.11357
27.11233
27.11368
27.11097
27.11097
27.10934
27.11154
27.11256
27.11238
27.11426
27.11357
27.11339
27.11223
27.11101
27.11101
27.11103
27.11246
27.11277
27.11425
27.11203
27.11060
27.11060
27.11060
27.11098
27.11104
27.11423
27.11334
27.11192
27.11637
-80.44915
-80.44917
-80.44748
X
-80.44805
-80.44798
-80.44845
-80.44781
-80.44849
-80.44849
-80.44862
-80.44879
-80.44886
-80.44856
-80.44762
-80.44862
-80.44834
-80.44825
-80.44902
-80.44902
-80.44906
-80.44836
-80.44877
-80.44764
-80.44855
-80.44917
-80.44918
-80.44918
-80.44846
-80.44806
-80.44758
-80.44830
-80.44895
-80.44865
3
3
1
X
1
2
2
1
3
3
1
1
1
1
2
1
1
1
3
3
3
1
1
1
1
3
3
3
3
3
2
1
3
1
X
X
2
X
X
X
2
X
2
2
2
X
X
X
2
X
X
X
4
4
X
X
X
X
X
3
3
3
2
X
X
X
X
X
Above
Ground
1
1
2
X
1
1
2
1
2
2
2
1
1
1
2
1
1
X
2
2
1
1
1
1
1
2
2
2
2
1
1
1
1
1
Burrow
X
X
1
X
1
1
1
1
2
1
1
1
1
1
1
1
1
1
2
2
2
1
1
1
1
2
2
2
2
2
2
1
1
1
85
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Nagini 73
Nagini 74
Nagini 75
Nagini 76
Nagini 77
Nagini 78
Nagini 79
Nagini 80
Nagini 81
Nagini 82
Nagini 83
Nagini 84
Nagini 85
Nagini 86
Nagini 87
Nagini 88
Nagini 89
Nagini 90
Nagini 91
Nagini 92
Nagini 93
Nagini 94
Nagini 95
Nagini 96
Nagini 97
Nagini 98
Nagini 99
Nagini 100
Nagini 101
Nagini 102
Nagini 103
Nagini 104
Nagini 105
Nagini 106
11/20/12
11/24/12
11/27/12
11/30/12
12/2/12
12/5/12
12/11/12
12/14/12
12/18/12
12/21/12
12/25/12
12/28/12
12/31/12
1/5/13
1/7/13
1/9/13
1/14/13
1/23/13
1/25/13
1/29/13
2/1/13
2/6/13
2/7/13
2/13/13
2/16/13
2/20/13
2/22/13
2/26/13
3/1/13
3/4/13
3/5/13
3/12/13
3/15/13
3/22/13
13:06
18:15
12:04
12:50
13:30
11:45
12:00
16:30
13:57
12:45
13:20
10:50
13:05
11:40
16:00
13:05
12:50
13:29
11:10
9:50
10:40
12:00
10:30
10:48
13:20
10:00
11:30
11:58
11:12
12:40
12:20
11:05
11:14
13:06
22
21
25
25
22
24
23
23
33
18
33
22
24
27
23
29
28
27
20
22
17
26
24
28
23
22
31
28
15
20
25
22
19
24
2
2
3
2
4
3
4
2
2
1
2
1
2
2
4
2
2
2
1
3
1
2
2
2
2
1
2
2
2
1
1
3
1
2
27.11400
X
27.11201
27.11681
27.11075
27.11062
27.11062
27.11062
27.11085
X
27.11294
27.11283
27.11289
27.11288
27.11293
27.11205
27.11060
27.11062
27.11064
27.11096
27.11151
X
27.11151
27.11135
27.11463
27.11147
27.11152
27.11151
X
X
27.11148
27.11212
27.11213
27.11098
-80.44842
X
-80.44897
-80.44882
-80.44917
-80.44916
-80.44917
-80.44917
-80.44887
X
-80.44914
-80.44916
-80.44916
-80.44918
-80.44933
-80.44915
-80.44915
-80.44914
-80.44916
-80.44847
-80.44780
X
-80.44843
-80.44845
-80.44839
-80.44847
-80.44842
-80.44843
X
X
-80.44842
-80.44803
-80.44779
-80.44870
1
X
3
1
3
3
3
3
2
X
3
3
3
3
3
3
3
3
3
3
1
X
1
2
2
2
1
2
X
X
2
1
1
3
X
X
X
X
X
3
3
3
X
X
X
X
X
8
3
3
3
3
3
2
2
X
3
X
X
X
X
X
X
X
2
X
X
8
Above
Ground
1
X
1
1
1
2
2
2
1
X
1
1
1
2
2
2
2
2
2
2
2
X
1
1
1
1
1
1
X
X
2
1
1
2
Burrow
1
X
1
1
2
2
2
2
1
X
2
2
2
2
1
1
2
2
2
2
1
X
2
X
X
X
X
X
X
X
1
X
X
2
86
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Nagini 107
Nagini 108
Nagini 109
Dagwood(Capture)
Dagwood(Release)
Dagwood 1
Dagwood 2
Dagwood 3
Dagwood 4
Dagwood 5
Dagwood 6
Dagwood 7
Dagwood 8
Dagwood 9
Dagwood 10
Dagwood 11
Dagwood 12
Dagwood 13
Dagwood 14
Dagwood 15
Dagwood 16
Dagwood 17
Dagwood 18
Dagwood 19
Dagwood 20
Dagwood 21
Dagwood 22
Dagwood 23
Dagwood 24
Dagwood 25
Dagwood 26
Dagwood 27
Dagwood 28
Dagwood 29
3/25/13
3/27/13
3/29/13
2/23/12
3/1/12
3/1/12
3/2/2012
3/2/12
3/6/2012
3/6/12
3/8/12
3/8/12
3/9/12
3/9/12
3/13/12
3/13/12
3/15/12
3/15/12
3/20/12
3/20/12
3/22/12
3/22/12
3/28/12
3/30/12
4/3/12
4/6/12
4/6/12
4/10/12
4/13/12
4/17/12
4/19/12
4/24/12
4/26/12
5/1/12
11:45
15:05
12:05
14:20
12:00
12:00
13:27
15:50
12:20
13:34
12:19
14:40
13:30
15:55
13:10
14:22
12:57
14:00
13:53
15:45
13:19
14:13
12:45
12:18
13:12
13:33
14:37
14:10
14:20
14:24
14:31
12:26
13:30
14:30
23
22
27
27
27
28
28
24
24
24
24
27
27
25
25
23
23
27
27
27
27
26
27
29
30
30
27
27
27
28
20
27
27
30
1
1
1
1
3
2
2
2
3
3
3
3
3
3
3
3
3
3
2
2
2
2
2
2
1
2
2
2
2
3
2
1
2
3
27.11101
27.11110
27.11099
27.10642
27.10642
27.10642
27.11023
27.11023
27.10997
27.10997
27.10858
27.10737
27.10737
27.10713
27.10428
27.10428
27.10483
27.10483
27.10755
27.10755
27.10775
27.10750
27.10730
27.10735
27.10738
27.10738
27.10738
27.10545
27.10513
27.11452
27.11192
27.11075
27.11013
27.10210
-80.44904
-80.44850
-80.44850
-80.43307
-80.43307
-80.43307
-80.43333
-80.43333
-80.43288
-80.43288
-80.43198
-80.43210
-80.43163
-80.43170
-80.43172
-80.43172
-80.43163
-80.43163
-80.43275
-80.43275
-80.43262
-80.43230
-80.43172
-80.43175
-80.43180
-80.43180
-80.43180
-80.43272
-80.43272
-80.43267
-80.43280
-80.43152
-80.43267
-80.43443
3
3
3
3
3
3
1
1
3
3
1
2
2
2
2
2
2
2
2
3
1
2
2
2
2
3
3
2
2
2
3
1
2
1
5
X
X
6
6
6
2
2
X
X
2
2
X
X
2
2
2
2
X
X
2
X
2
2
2
2
2
2
2
X
2
X
2
X
Above
Ground
1
1
1
2
2
2
2
2
X
X
2
2
X
1
2
2
2
2
1
1
2
1
2
2
2
2
2
2
2
1
2
1
2
1
Burrow
2
X
X
2
2
2
1
1
X
X
1
1
X
X
1
1
1
1
X
X
1
X
1
1
1
1
1
1
1
X
1
X
1
X
87
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Dagwood 30
Dagwood 31
Dagwood 32
Dagwood 33
Dagwood 34
Dagwood 35
Dagwood 36
(Dead)
Paul(Capture)
Paul(Release)
Paul 1
Paul 2
Paul 3
Paul 4
Paul 5
Paul 6
Paul 7
Paul 8
Paul 9
Paul 10
Paul 11
Paul 12
Paul 13
Paul 14
Paul 15
Paul 16
Paul 17
Paul 18
Paul 19
Paul 20
Paul 21
Paul 22
Paul 23
Paul 24
5/4/12
5/7/12
5/11/12
5/11/12
5/15/12
5/17/12
12:30
12:25
8:40
12:00
13:24
16:33
33
28
28
29
28
30
2
2
2
2
2
3
27.11025
27.10678
27.10672
27.10672
27.10552
27.10497
-80.43333
-80.43383
-80.43380
-80.43380
-80.43347
-80.43353
1
1
1
1
1
2
2
2
2
2
2
2
Above
Ground
2
2
2
2
2
2
5/22/12
6/28/12
7/25/12
7/25/12
7/26/12
7/30/12
7/31/12
8/3/12
8/11/12
8/14/12
8/17/12
8/21/12
8/24/12
8/28/12
8/31/12
9/4/12
9/7/12
9/11/12
9/14/12
9/18/12
9/18/12
9/21/12
9/25/12
9/28/12
10/2/12
10/5/12
10/9/12
13:20
13:15
18:31
1:46
10:05
18:50
8:40
X
9:24
9:12
11:36
12:23
9:55
12:32
11:00
X
12:46
9:00
11:18
9:00
10:15
1:27
13:43
13:03
9:05
12:47
13:32
86
29
35
27
29
28
27
29
27
32
31
32
29
29
31
29
31
25
29
25
25
29
29
31
25
31
29
3
2
1
1
2
2
1
2
3
1
2
2
2
2
2
4
2
1
3
1
1
4
2
2
4
2
2
27.10450
27.07840
27.07841
27.07950
27.08199
27.07744
27.07710
X
27.07682
27.07817
27.07588
27.07785
27.07700
27.07775
27.07776
X
27.07920
27.07879
27.07599
27.07914
27.07914
27.07913
27.07913
27.07881
27.07792
27.07643
27.07695
-80.43640
-80.44962
-80.44963
-80.44962
-80.44936
-80.44839
-80.44839
X
-80.44820
-80.44905
-80.44898
-80.44868
-80.44821
-80.44781
-80.44781
X
-80.44865
-80.44900
-80.44873
-80.45001
-80.45001
-80.45000
-80.45000
-80.44898
-80.44807
-80.44341
-80.44813
1
3
3
3
3
2
2
X
2
1
1
1
1
2
2
X
1
1
2
2
2
2
2
1
2
2
2
X
7
7
3
X
X
X
X
2
X
X
2
2
X
X
X
X
2
X
2
2
2
2
2
X
X
X
1
2
2
2
1
1
1
X
2
1
1
2
2
1
1
X
1
2
1
2
2
2
2
2
1
1
1
Burrow
1
1
1
1
1
1
X
2
2
2
X
X
X
X
1
X
X
1
1
X
X
X
X
1
X
1
1
1
1
1
X
X
X
88
Snake_ID
Date
Time
Temp_C
Cloud
N DD.DDDDD
W DD.DDDDD
Habitat
Refugia
Paul 25
Paul 26
Paul 27
Paul 28
Paul 29
Paul 30
Paul 31
Paul 32
Paul 33
Paul 34
Paul 35(Dead)
10/13/12
10/16/12
10/19/12
10/24/12
10/30/12
11/2/12
11/6/12
11/9/12
11/11/12
11/16/12
11/20/12
10:15
15:50
10:30
11:10
16:24
11:10
14:45
14:15
12:30
16:23
13:43
28
29
36
35
25
25
26
25
27
21
23
2
2
1
2
1
1
3
2
1
3
2
27.07832
27.07830
27.07833
27.07880
27.07849
27.07810
27.07896
27.07935
27.07889
27.08036
27.08076
-80.44627
-80.44628
-80.44627
-80.44899
-80.44961
-80.44961
-80.45005
-80.44973
-80.44960
-80.44748
-80.44747
1
2
1
1
3
3
2
1
3
2
2
2
2
2
2
X
X
2
2
X
X
X
Appendix Table 3
Above
Ground
2
2
2
2
1
1
2
2
1
1
1
Burrow
1
1
1
1
X
X
1
1
X
X
X
Key for Data
Cloud Cover
1= Clear
2= Partly cloudy
3= Overcast
4= Rain
-
Habitat
1= Upland
2= Wetland/ ditch
3= Canal/ bank
4= Forested
5= Other
-
Refugia
1= Gopher tortoise
2= Mammal burrow
3= Pipe
4= Rock pile
5= Building structure
6= Coverboard
7= Junction box
8= Other
X= Unknown
This table provides the meaning of numerals used to abbreviate raw data.
Above Ground
1= Above ground
2= Below ground
X= Unknown
-
Burrow
0= NA
1= Natural
2= Artificial
-

Home range size and habitat use of the Eastern

Transcription

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