Pawnee montane skipper technical report

Trout Creek Pawnee Montane Skipper
(Hesperia leonardis montana)
Survey 2014
December 2014
CNHP’s mission is to preserve the natural diversity of life by contributing the essential scientific
foundation that leads to lasting conservation of Colorado's biological wealth.
Colorado Natural Heritage Program
Warner College of Natural Resources
Colorado State University
1475 Campus Delivery
Fort Collins, CO 80523
(970) 491-7331
Report Prepared for:
Wild Connections
2168 Pheasant Pl.
Colorado Springs CO 80909
Recommended Citation:
Sovell, J. R. 2014 Trout Creek Pawnee montane skipper (Hesperia leonardis montna) survey 2014.
Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado.
Front Cover: Male Pawnee montane skipper nectaring along Trout Creek, September 1, 2010. © Colorado
Natural Heritage Program, John Sovell
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Trout Creek Pawnee Montane Skipper
(Hesperia leonardis montna)
Survey 2014
John Sovell
Colorado Natural Heritage Program
Warner College of Natural Resources
Department of Biology
College of Natural Sciences
Colorado State University
Fort Collins, Colorado 80523
3
CONTENTS
INTRODUCTION ............................................................................................................................................. 5
METHODS...................................................................................................................................................... 5
RESULTS ........................................................................................................................................................ 6
DISCUSSION/RECOMMENDATIONS .............................................................................................................. 5
APPENDIX 1. DESCRIPTION OF PROJECT TRANSECTS ................................................................................... 7
LIST OF TABLES
Table 1. Butterfly and vegetation data from each of the legs surveyed at both of the Trout Creek Trail
transects surveyed during 2014............................................................................................................... 7
Table 2. The data collected from transects 1 and 2 at the Trout Creek Trail during the 2010, 2012
and 2014 surveys. .................................................................................................................................. 7
Table 3. Multivariate ANOVA results for Pawnee montane skippers, comma skippesr, total skippers, blue
grama, dotted gayfeather, live trees and dead trees. ............................................................................. 5
LIST OF FIGURES
Figure 1. The Trout Creek transect and the location of each 200 m station along the transect. Station E
designates the endpoint of each transect. The Polhemus fire and the estimated suitable habitat for the
Pawnee montane skipper (Hesperia leonardus montana) butterfly are also shown. ........................... 12
Figure 2. The locations of the Pawnee montane skipper (Hesperia leonardus montana) butterfly and the
unidentified skippers documented along the Trout Creek transect in 2014. The Polhemus fire and the
estimated suitable habitat for the Pawnee montane skipper butterfly are also shown....................... 13
LIST OF PHOTOS
Photo 1. The relatively flat, open, and sunny topography of transect 1, which parallels Trout Creek. ....... 7
Photo 2. The narrow, deep, shaded, and steep sided gully of transect 2 where restoration is taking place.9
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INTRODUCTION
The Colorado Natural Heritage Program (CNHP) is Colorado’s only comprehensive source of information
on the status and location of Colorado’s rarest and most threatened species and plant communities.
CNHP tracks and ranks Colorado’s rare and imperiled species and habitat and provides scientific
information and expertise to promote the conservation of Colorado’s biological resources. Established in
1979, the CNHP is a non-profit scientific organization affiliated with the Warner College of Natural
Resources at Colorado State University.
CNHP conducted field surveys in 2010 and 2012 for the Pawnee montane skipper (Hesperia leonardus
montana) butterfly along two trail corridors adjacent to Trout Creek in the Pike National Forest, Douglas
County, Colorado. This survey is an extension of those 2010 and 2012 surveys. Wild Connections
contracted with Colorado State University - Colorado Natural Heritage Program (CSU-CNHP) to provide a
survey to provide a survey of Pawnee montane skipper at this site. There were three objectives of these
surveys:
1. Understand how restoration of a section of the trail corridor running east from the creek up a steep
gully (designated Trout Creek transect 2 in this report) improves the habitat for the federally threatened
Pawnee montane skipper butterfly.
2. Identify the abundance Pawnee montane skipper butterflies inhabiting the trail corridor on either of
the two surveyed transects.
3. Identify the relative frequency on the two transects of blue grama (Bouteloua gracilis) and relative
abundance of dotted gayfeather (Liatris punctata) stems, the larval host plant and primary adult nectar
source, respectively, of the Pawnee montane skipper.
METHODS
Two 800-meter (m)-long belt transects were located along the corridor of the Trout Creek Trail (Figure1).
The survey area width for each belt transect was 10 m (5 m on either side of the transect center line). The
effective area surveyed was 8,000 m2 (800 m x 10 m), which is equivalent to 1.98 acres. Trout Creek
transect 1 runs parallel to Trout Creek, crosses relatively level ground along the trail corridor, is free of
erosion, and has not required restoration work. Trout Creek transect 2 follows the trail corridor up a
steep gully and the steep incline combined with heavy motorcycle use on this trail section has caused
excessive erosion requiring extensive restoration work. The restoration was completed by Wild
Connections in 2009 and 2010. Trout Creek transect 2 is also located within the boundary of the
Polhemus Fire and the forest of transect 2 experienced a low intensity burn from that fire.
Each of the 800-meter (m) belt transects were divided into four legs (A through D) of 200 m length
creating five separate transect stations; one each starting at 0 m, 200 m, 400m, and 600m (Figure 1). Each
5
200 m leg was further divided into 10, 20 m sub-segments resulting in 40 separate sampling segments
along each 800 m belt transect.
Each 200-m leg was walked, and data were recorded for each of the10, 20-m sub-segments along the
200-m transect leg. The following data were collected along each 20-m sub-segment:
- Tree counts. Live trees greater than 6 inches diameter at breast height (DBH) within the belt transect (5
m on each side of the transect center point) were counted to document the larger living trees along the
transect in both burned and unburned areas. Also, dead standing trees greater than 6 inches DBH were
counted and recorded in a separate category (particularly pertinent to transect 2 in the Polhemus Fire
area).
- Blue grama (Bouteloua gracilis) (Bogr) frequency. The presence or absence of blue grama was
documented within a visually estimated 0.5-m-square rectangular quadrant that extended 0.5 m on
either side of the observer’s toe, and 0.5 m in front of the toe at the endpoint of each 20-m interval along
the transect (10 recordings per 200-m segment). The observer marked + or √ for presence, 0 for absence
in the appropriate space on the data sheet.
- Dotted gayfeather (Liatris punctata) (Lipu) stem counts. Stems of blooming Dotted gayfeather were
counted in each 20-m segment within the 10-m wide belt of the transect. Commonly there were multiple
blooming stems emanating from the crown of an individual Liatris plant. Each stem was counted as a
separate occurrence.
- Adult skipper butterfly counts (Hesperia leonardus montana [Hlm] and Hesperia comma [Hco]).
Individual skipper butterflies of either the Pawnee montane skipper or the common branded skipper
were counted in each 20 m segment within the 10-m wide belt of the transect. The sex of the skipper was
recorded if it was ascertainable. If the skipper species was unknown, its occurrence was entered as an
unknown skipper, and the sex was recorded if it was ascertainable.
RESULTS
The 2014 field survey documented 8 Pawnee montane skipper butterflies along portions of both of the
Trout Creek Trail transects (Table 1 and Figure 2). This is nearly as many Pawnee montane skippers as
were observed on the same two transects in 2012 (11) and double the 4 that were observed in 2010
(Table2). Five of these Pawnee montane skippers were observed on Transect 1, while 9 were observed in
2012 and 3 in 2010. Three of the 8 Pawnee montane skippers were observed on Transect 2 in 2014
versus 2 in 2012 and 1 in 2010. Of the 8 Pawnee montane skippers recorded, 5 were males with 2
observed on Transect 1 and 3 on transect 2; 3 were females all observed on Transect 1 (Table 1).
Additionally, 5 comma skippers were observed in 2014, while 5 were also observed in 2012, but 0 were
seen in 2010. In 2014, there were also 9 skippers observed that could not be identified because of their
fast flight and the short time they remained visible; 6 on Transect 1 and 3 on Transect 2 (Table 1 and
Figure 2). In 2012, there were 11 skippers that could not be identified, while 6 could not be identified in
2010. In 2014, there were 22 Pawnee, comma, and unknown skippers observed on both transects, similar
to the 27 observed in 2012 and over twice that of the 10 seen in 2010.
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Table 1. Butterfly and vegetation data from each of the legs surveyed at both of the Trout Creek Trail transects surveyed during 2014.
Burn
Transect Intensity Date
Year UTME
UTMN
Start End Live Dea
Hlm Hlm
Hlm
Leg Time Time Tree d
Bogr Lipu Mal Femal ?
0 1
1 1
53  1  1
Hco
Male
Hco
UNK UNK UNK
Femal Hco? male femal ?
TroutCr1
1 8/30/2014 2014 486356 4340795 A
9:55 10:14
28
0
10
15
0
0
0
0
1
0
0
TroutCr1
1 8/30/2014 2014 486441 4340618 B
10:18 10:33
16
0
4
22
0
0
0
0
0
0
0
TroutCr1
TroutCr1
TroutCr2
TroutCr2
TroutCr2
TroutCr2
1
1
2
2
2
2
10:33
10:50
11:06
11:20
11:44
11:58
10:48 15
11:07 13
11:19 51
11:40 27
11:57 29
12:15 37
Tota l 216
0
0
0
0
0
0
0
7
6
0
1
0
0
28
0
1
3
1
1
96
0
0
0
0
0
0
0
3
0
0
1
0
0
4
0
0
0
1
0
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
0
0
5
1
1
1
0
8
8/30/2014
8/30/2014
8/30/2014
8/30/2014
8/30/2014
8/30/2014
2014
2014
2014
2014
2014
2014
486608
486765
486882
487039
487195
487362
4340506
4340387
4340188
4340279
4340365
4340385
C
D
A
B
C
D
3
0
0
0
0
0
0
0
3
0
0
5
Bogr = Bouteloua gracilis, Lipu= Liatris punctata, HIm = Hespena leonardus montana, Hco = Hespena comma and UNK = unknown skipper.
Table 2. The data collected from transects 1 and 2 at the Trout Creek Trail during the 2010, 2012 and 2014 surveys.
Sample
Block
Burn
Date
Year
UTME
UTMN
Leg
Start
End
Live
Dead
Time
Time
Trees
Trees
Bogr
Lipu
Hlm
Hco
UNK
TOTAL
TroutCr1
0
9/2/2010
2010
486822
4340172
D
10:42
11:48
90
0
23
38
3
0
3
6
TroutCr2
1
9/2/2010
2010
487395
4340202
D
11:55
13:26
260
11
3
31
1
0
3
4
TroutCr1
0
9/1/2012
2012
486822
4340178
D
11:24
12:37
62
0
23
30
9
2
5
16
TroutCr2
1
9/1/2012
2012
487395
4340186
D
12:46
14:10
122
1
2
0
2
3
6
11
TroutCr1
0
8/31/2014
2014
486765
4340387
D
9:55
11:07
72
0
27
90
5
3
6
14
TroutCr2
1
8/31/2014
2014
487362
4340385
D
11:06
12:15
144
0
1
6
3
2
3
8
Bogr = Bouteloua gracilis, Llpu = Liatris punctata, HIm = Hespena leonardus montana, Hco = Hespena comma, and UNK = unknown skipper.
A multivariate analysis of variance (MANOVA) performed on the data, comparing the number of Pawnee,
coma and all skippers seen during the three years surveyed did not show any statistically significant
differences between the two transects (Table 3). A MANOVA performed on live and dead trees, blue grama
and dotted gayfeather found significantly more blue grama and marginally significantly more live trees on
Transect 2 (Table 3).
Table 3. Multivariate ANOVA results for Pawnee montane skippers, comma skippesr, total skippers, blue grama,
dotted gayfeather, live trees and dead trees.
Sum of
d. f.
Squares
F
P
Transect 1
Transect 2
Mean
Mean
Pawnee montane skipper
Transect
20.17
1
3.90
0.12
5.67
2.00
Comma skipper
Transect
0.00
1
0.00
1.00
1.67
1.67
Total skippers
Transect
28.17
1
1.40
0.30
12.00
7.67
1
24.33
2.00
0.13
52.67
12.33
2
74.67
175.33
0.32
0.00
4.00
Blue grama
Transect
748.17
1
236.26
Dotted gayfeather
Transect
2440.2
1
3.66
Live Trees
Transect
15,201
1
5.33
Dead trees
Transect
24
1
1.29
1
2
0.0001
0.08
Statistically significant at p = 0.05.
Statistically significant at p = 0.1.
DISCUSSION/RECOMMENDATIONS
The 2014 survey once again documented the occurrence of Pawnee montane skipper on both Trout Creek
transects. Skippers decreased in 2014 compared to 2012. However, there were no statistically significant
differences in the number of total, Common branded or Pawnee montane skippers observed between the
two transects in 2014 versus either 2010 or 2012. There were more Pawnee montane skippers observed on
Transect 2 in 2014 than in either 2010 or 2012 suggesting that the restoration effort may be increasing
habitat quality for the skipper on Transect 2. In three years of sampling, there have been 17 Pawnee
montane skippers observed on Transect 1 versus 6 on Transect 2. Empirically, the habitat of Transect 1
appears more suitable for Pawnee montane skippers than that of Transect 2, lending support to the data.
For the purposes of this study, the detection of statistically significant increases in Pawnee montane
skipper numbers on Transect 2 since completion of the trail restoration work would supply evidence that
the restoration has benefitted the Pawnee montane skipper, increasing the suitability of the habitat of
Transect 2 for the butterfly. The data is showing an increase of Pawnee montane skipper numbers on
Transect 2. The changes to the environment realized through restoration of the trail may not lead to large
increases in the butterfly’s numbers. This is because they require open canopy ponderosa pine woodland
with an understory that includes the larval host plant, blue grama, and presence of the primary adult
nectar source, dotted gayfeather. Doted gayfeather was not observed on Transect 2 in 2012 and only 6
5
flowering stems were recorded in 2014. Additionally, there has only been an average frequency of 5% of
blue grama on Transect 2 over all three years surveyed. This, combined with a dense forest canopy on the
transect may be more limiting to the butterfly than are the benefits realized from restoration of the trail.
Additional monitoring of the butterfly at the two transects will help clarify whether the trail restoration will
increase numbers of the Pawnee montane skipper at the restored site. As mentioned in the previous
reports, forest thinning might be the most beneficial management action for the Pawnee montane skipper
on Transect 2. Years of fire suppression on the Pike National Forest has resulted in an overly dense tree
canopy, which the Polhemus and Hayman fires were responding too. However, the actual reference state
for tree density on this forest is unknown and tree density within the deep gullies of the forest may have
been higher than on the less steep slopes and hilltops of the surrounding landscape. Forest thinning as has
been prescribed to improve habitat suitability for the Pawnee montane skipper would benefit the Pawnee
montane skipper at this site (Sovell 2014). Additional restoration at Transect 2 involving the reestablishment of native vegetation including blue grama and dotted gayfeather would improve the habitat
for the Pawnee montane skipper and further reduce erosion on the steep slopes of the transect.
Additional monitoring at the site could potentially find that Pawnee montane skippers continue to
increase in numbers on Transect 2, the restored transect.
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APPENDIX 1. DESCRIPTION OF PROJECT
TRANSECTS
Transect 1
This transects follows the base of the slope crossing relatively flat terrain along Trout Creek (Photo 1). The
richer soils of this flat creek-side area and the high solar radiation resulting from an open forest canopy
support abundant blue grama grass and moderate amounts of dotted gayfeather. Lower elevation,
relatively flat areas, with abundant sunlight where the tree canopy tends to thin, support the largest
densities of blue grama and dotted gayfeather, and this area is no exception. In three years of sampling
there was a 61% frequency of blue grama along this transect, which represents an abundant amount of
blue grama. Over 10 years of monitoring in the Hayman Fire area the average frequency of blue grama was
13% and the average density of dotted gayfeather was 67 stems/acre (Sovell 2012). The high frequency of
blue grama and moderately abundant gayfeather (27 stems/acre) make this important habitat for
maintaining the metapopulation dynamics of this rare butterfly. Conserving and restoring populations of
blue grama and dotted gayfeather are vital to conserving the butterfly. Care should be taken to avoid
broadcast spraying of pesticide and herbicides that could negatively impact the butterfly, its host plant blue
grama, or dotted gayfeather the butterfly’s primary adult nectar source.
Photo 1. The relatively flat, open, and sunny topography of transect 1, which parallels Trout Creek.
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Transect 2
Transect 2 is comprised of the restored trail segment that lies in a gully with a dense overstory of conifers,
where shading is high and little blue grama was recorded (Photo1, Table 1, and Figure 1). In general, the
habitat of transect 2 is less suitable for Pawnee montane skippers and this is evidenced by the high live
tree count (260 in 2010, 122 in 2012, and 144 in 2014) and the low 5% frequency of blue grama recorded
on the transect (7.5% in 2010, 5% in 2012 and 2.5% in 2014) compared to the 13% frequency recorded
over 10 years of monitoring in the Hayman Fire area (Sovell 2012). In 2010, however, there was a
moderate amount of dotted gayfeather with 31 stems or 15.7 stems/acre counted on the transect, but in
2012 dotted gayfeather was not observed on Transect 2 and in 2014 only 3 stems/acre were recorded.
The oviposition flight of a female Pawnee montane skipper was observed on this transect in 2010 and
there are patches of suitable habitat scattered along the hilltops crossed by the transect.
The restoration project completed on transect 2 stabilized this segment of the trail corridor through the
placement of water bars, check dams, erosion mat, and drainage swales, which prevented further erosion,
helping to restore native vegetation to these eroded areas. Stabilization of the trail corridor will prevent
erosion of upslope areas above and adjacent to the restored corridor. This should reduce erosion of the
hilltop areas above the trail corridor that are adjacent to the restored areas. In this hilly and gullied
topography it is these hilltop sites that the Pawnee montane skipper occupies. In this type of terrain the
hilltop areas have richer soils and a higher content of soil moisture relative to the surrounding slopes, less
dense tree cover, and less shading due to fewer trees and the relative flatness of the hilltop, all of which
leads to higher solar radiation and more abundant blue grama grass and dotted gayfeather relative to the
adjoining areas.
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Photo 2. The narrow, deep, shaded, and steep sided gully of transect 2 where restoration is taking place.
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REFERENCES
Sovell, J. R. 2012. Pawnee montane skipper post fire habitat assessment survey – August/September
2012. Colorado Natural Heritage program, Colorado State University.
Sovell, J. R. 2014. Pawnee Montane Skipper Vegetation Study for the Upper South Platte Watershed
Protection and Restoration Project - September 2012. Colorado Natural Heritage Program, Colorado
State University.
ADDITIONAL RESOURCES
Sovell, J. R. 2010. Trout Creek Pawnee montane skipper (Hesperia leonardus montana) survey –
August 31, 2010, Colorado Natural Heritage Program, Colorado State University.
Sovell, J. R. 2012. Trout Creek Pawnee montane skipper (Hesperia leonardus montana) survey –
November 2012, Colorado Natural Heritage Program, Colorado State University.
ACKNOWLEDGEMENTS
Grants from Cheyenne Mountain Zoo were awarded to Wild Connections to underwrite the 2010 and
2012 surveys and a grant from Prairie Biotic Research to John Sovell and designated funds from Wild
Connections underwrote the 2014 survey.
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FIGURES 1 and 2
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Figure 1. The Trout Creek transect and the location of each 200 m station along the transect. Station E designates
the endpoint of each transect. The Polhemus fire and the estimated suitable habitat for the Pawnee montane
skipper (Hesperia leonardus montana) butterfly are also shown.
12
Figure 2. The locations of the Pawnee montane skipper (Hesperia leonardus montana) butterfly and the
unidentified skippers documented along the Trout Creek transect in 2014. The Polhemus fire and the estimated
suitable habitat for the Pawnee montane skipper butterfly are also shown.
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