Reproduction of Eastern bluebirds in relation to land management

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Suggested Citation: Author Full Name. Title of Presentation or Handout. 2011
University of Florida-IFAS and Florida Agricultural and Mechanical UniversityCESTA Florida Small Farms and Alternative Enterprises Conference. July 15-17,
Kissimmee, FL.
Birds in Your Fields: What’s the Bottom Line?
Kathryn E. Sieving, Professor
Wildlife Ecology & Conservation
University of Florida, Gainesville
Conservation & Agriculture
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Historically schizophrenic relationship
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Pre-1900’s: farms = habitat (birds = ’beneficial’)
1900’s: industrial farms = ‘clean’ (birds = ‘pests’)
Ye Olde- tyme Farm …..
Mols and Visser. 2007. PLoS 1
Ye New-fangled Farm.
Peterjohn. 2003. Auk.
Conservation & Agriculture
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Today, partnership is necessary
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NRCS
Ag wants ecological sustainability (incl. biodiversity)
Conservation needs productive ag-lands
Need to Partner !!!
“…endangered species and poor humans occupy the same
ground," … Sara J. Scherr, 2001.
Nearly half of the world's nature reserves are being heavily farmed…
National Geogr. 2001
“…the most common approach to wildlife conservation —designating
areas in which to protect threatened plant and animal species in their
native ecosystems —is failing”. McNeely and Scherr, 2001
“…internal regulation of function in agroecosystems is largely dependent on
the level of plant and animal biodiversity present.” Miguel Altieri, 1999.
~ 45% of the world’s plants (NPP) are cultivated . Ellis and Ramankutty 2007
Outline: Bottom Line Birds
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Research Highlights – Sieving Lab
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Management Recommendations
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Key Findings & Summary
Fostering birds on your farm
Keeping the relationship positive
Wrap-up
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What we know and don’t know (but need to)
Caveats / Cautions
Research Highlights
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Two Perspectives
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Birds= Friendly?
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Pest or Beneficial?
System-, Species-dependent
Farms = Friendly?
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Suitable Habitat or Ecological Trap?
Management-, scale-dependent (Robertson & Hutto. 2006. Ecology)
Research Highlights
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Previous research (2000-2006)
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Surveys of birds on farms – who’s using farms?
Insectivorous bird activity on farms – munching pests!
Experiments with sunflower intercrops
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as ‘predator refugia’ to attract bird & bug predators on pests
Recent Research (2007-2009)
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Bluebirds!
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Insect eating and Breeding success on farms
Research Highlights
Surveys of birds on
Conventional, Organic,
& Sustainably-managed Farms,
NC FL
•Species we recorded = 82% of resident
and migratory landbird species listed as
breeders in Alachua County and 96% of
those in recent breeding bird surveys.
•We observed 24 listed species on organic
farms (18 state, 6 federal) and 18 listed
species on conventional farms.
•Farms host lots of important species
Jones, Sieving, Jacobson. 2005. Con. Bio.
Research Highlights
Landscape and
farm vegetation matters
Woodlands adjacent to farm
brought more birds onto farms
and into the fields.
Fields and farms with mixed crop types in
fields had more birds.
Research Highlights
We identified 10 ‘functional insectivores’
Species seen in crops eating bugs frequently.
Jones and Sieving. 2006. Agr. Ecos. Env.
Research Highlights
Common Name Forager (*)
Acadian Flycatcher
American Crow *
American Goldfinch *
American Kestrel
American Redstart *
Barred Owl
Bay-breasted Warbler *
Blackpoll Warbler *
Blue-gray Gnatcatcher
Blue-headed Vireo
Blue Grosbeak *
Blue Jay *
Bobolink *
Brown-headed Cowbird
Brown Thrasher *
Boat-tailed Grackle *
Cape May Warbler
Carolina Chickadee *
Cattle Egret *
Carolina Wren *
Cedar Waxwing
Chimney Swift
Common Grackle
Common Ground Dove *
Common Yellowthroat *
Downy Woodpecker
Table 1 (part) Some of the species
observed within cropped fields or within
50 m of cropped fields of organic
farmlands in North-central Florida during
the breeding seasons 1 April
through 30 June 2000 - 2003.
The most commonly observed insect eating
species are bold faced.
Those species observed foraging within
crop vegetation are indicated with an
asterisk.
Research Highlights
Insects being eaten are frequently
pest species.
We put digital cameras on their nests.
We saw the insects being eaten;
We captured birds, pumped their tummies,
and then looked under the microscope.
Research Highlights
The Sunflower Effects: Pest-eating Birds
Research Highlights
How were birds using the sunflowers?
Perches, and corridors of cover!!
Research Highlights
The Sunflower Effects: Pest-eating (Beneficial) Bugs
Research Highlights
The Sunflower Effects:
Pest-eating (Beneficial) Bugs
Mymaridae Mymarid Wasps parasite
Oxyopidae Lynx Spiders predator
Papilionoidae Swallowtail Butterflies pollinator
Pentatomidae Predatory Stink Bugs predator
Plutellidae Diamond-backed Moths pollinator
Reduviidae Assassin Bugs predator
Scarabaeidae Scarab Beetles predator
Sphecidae Sphecid Wasps parasite
Tenebrionidae Darkling Beetles predator
Thomisidae Crab Spiders predator
Tiphiidae Tiphiid Wasps parasite
Trichogrammatidae Trichogrammatid Wasps parasite
Vespidae Vespid Wasps parasite
Research Highlights
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Eastern bluebirds / nest boxes
Farms
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Leafy vegetables, row crops (melon/corn/tobacco/flowers)
Natural grass-lands (controls)
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Ordway Biological Station; Ruderal (structure ~ farm fields)
Research Highlights - Bluebirds
Study Areas and Sample Sizes
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2007: conventional (6 sites), organic farms (8); natural (4)
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total boxes placed ~ 120
total 1st clutches = 47
total clutches = 105
2008: organic farms (4 sites); natural (6)
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total boxes placed ~ 80
total 1st clutches = 38
total clutches = 95
Methods
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Monitored boxes
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2007: every 3-4 days,
March through early August
2008: 7-10 days, March to June
Poles greased (no predation)
Methods
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Nest box data
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production of eggs, hatchlings,
fledglings, clutches, and nestling
growth measures; banded chicks
Methods
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Food Resources
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Prey delivery ID / rates
Ground arthropod surveys
GW = grasshopper walk
20 m
BW = lepidop larvae surveys
Research Highlights: timing of nesting
Farm bluebirds nested earlier (~2 weeks)
Research Highlights: nesting success ‘07
Farm birds worked harder, longer, same total # chicks.
Research Highlights: nesting success ‘08
Significantly lower hatching success (1st clutches) on farms in 08.
07
08
07
08
Research Highlights: food ‘07
Org. Farms had more insects, but higher variation.*
Research Highlights: food ‘08
Where birds started breeding
earlier,
there were more insects
(on farms, with irrigation)
Research Highlights: food ‘08
The more variable the
insect counts (among
samples)
the lower the hatching
success was
(again n farms).
Bluebird Findings - Overview
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Reproduction (2007 and 2008)
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Worse for farm-nesting bluebirds
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2007: inefficient (high effort / fledgling ratio)
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Nested earlier, more eggs/clutches, same # fledglings
2008: poor (~60% of hatchlings on natural area)
Food (2008)
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More prey, earlier on farms, but high variance
in food
Research Summary (1):
What Makes a Farm ‘Bird-Friendly’?
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Landscape Structure
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Forest in the landscape surrounding the farm
On Farm Characteristics that are Good for Birds
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Mixed crops in each field
Shrubs and trees along farm edges
Sunflowers (big ones!) and perches in fields
Irrigation! Causes earlier breeding
Insects! Stable populations
Research Summary (2):
What Makes a Bird ‘Farm-Friendly’?
Pest Eating!!!
Cardinals foraging in fields
Up to 25 ‘crawlers’/hr
~ 100-150/day
Bluebird families
17-300 prey/day
- lepidop larvae / orthops
- deliveries to nests
What we don’t know
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If birds can influence damage enough
to increase yield/price.
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Role of disturbance on farms for bird
well-being.
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Need more studies on working farms.
Activity and harvest – disrupts behavior
and food.
Flower intercrops – species matters
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Leaf-footed bugs also like sunflowers!
Summarize – what we know
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Most birds on small farms are friendly to farmer
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Insects = main food during spring growing season
Small Farms can be bird-friendly
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Maximize trees/shrubs
Provide perches (flowers/sprinklers)
Provide stable insect populations?
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Herbaceous verges away from crops?
Mixed crops in fields
Caveats – ’unfriendly’ birds
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This work applies principally to
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Organic vegetable farms
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Blueberries, grapes, melons, grains need to repel birds
Caveats – ’unfriendly’ farms
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Pesticides have direct negative effects on birds
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Pest-eating birds eat insects & need insects.
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See Journal of Pesticide Reform
But mostly, they destroy ‘friendly birds’ prey
Carefully target to crop - not intercrops or field edges
Use as little as needed
We don’t advocate birds in high-input systems
New challenges for birds and food!
Thanks! – the Royal We …
John DeLuca (bluebirds) and many student helpers and
many more growers in NC FL.
Questions?
Funding
University of Florida Foundation
Organic Farming Research Foundation
USDA – Southern SARE
UF (Wildlife Ecology)