Parents or Predators: Examining Intraseasonal Variation in Nest Survival for a Migratory Passerine

For birds, risk of nest predation can vary within a breeding season, but few data exist that explain why such variation occurs. We investigated intraseasonal variation of nest survival of the Acadian Flycatcher (Empidonax virescens) in Midwestern forests and tested whether four of the adults' r...

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Bibliographic Details
Published in:The Condor (Los Angeles, Calif.) Calif.), 2012-05, Vol.114 (2), p.358-364
Main Authors: Hirsch-Jacobson, Robin, Cox, W. Andrew, Tewes, Emily E, Thompson, Frank R, Faaborg, John
Format: Article
Language:English
Subjects:
Acadian Flycatcher
Animal behavior
Animal breeding
Animal nesting
Aviculture
Bird migration
Bird nesting
Birds
Breeding seasons
Clutch size
Demography
Empidonax virescens
Flycatchers
Incubation
Life sciences
nest survival
nest-visitation rates
Nests
Ornithology
Parametric models
Predation
Predators
reproductive strategies
RESEARCH PAPERS
Seasonal variations
seasonality
Seasons
Survival
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Summary:For birds, risk of nest predation can vary within a breeding season, but few data exist that explain why such variation occurs. We investigated intraseasonal variation of nest survival of the Acadian Flycatcher (Empidonax virescens) in Midwestern forests and tested whether four of the adults' reproductive strategies (clutch size, nest concealment, nest visitation rates, nest height) explained trends in survival across the breeding season. We also used video cameras to identify predators at 40 nests, which allowed us to determine whether variation in predation rates by category of predator (e.g., birds, mammals, snakes) explained overall seasonal variation in predation rates. The flycatchers' nest survival had a quadratic relationship with Julian date but generally increased through the breeding season. Nest height increased as the breeding season progressed but did not explain any variation in nest survival. No other reproductive trait exhibited significant intraseasonal variation. Overall, predator-specific predation rates did not vary seasonally, but there was a marginal decline in the risk of failure from avian predators as the season progressed. Of the explanations we considered, changes in predator abundance or activity were likely the primary contributor to intraseasonal variation in survival of Acadian Flycatcher nests.
ISSN:0010-5422
1938-5129
2732-4621
DOI:10.1525/cond.2012.110057