Abstract Title

Consequences of Timing: How Does Synchronization between Brood Rearing and Prey Availability Affect American Kestrel (Falco sparverius) Reproduction?

Disciplines

Ornithology | Population Biology

Abstract

Previous studies have indicated that over the past 20 years winters have warmed, but spring temperatures remain unchanged in southwestern Idaho. During this time, American kestrels (Falco sparverius) have advanced their nesting period by 28 days. Changes in nesting phenology may result in early-breeding kestrels raising young before important peaks in prey availability occur, while later-breeding kestrels may have a greater likelihood in raising young during peak prey availability. We hypothesize that the degree of synchronization with prey availability affects kestrel reproduction and predict that nesting events synchronized with prey availability will produce young in better condition than asynchronous nests. We used morphological measurements of nestlings gathered since 2008 from a sample area containing ≈ 120 nest boxes to assess condition. We calculated a synchrony index for each nest based on the clutch initiation date and annual patterns of NDVI, a predictor of prey abundance. We then used the synchrony index to predict nestling growth. As climate change continues to intensify, it is crucial to learn how these changes impact the reproductive success of wildlife populations.

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Consequences of Timing: How Does Synchronization between Brood Rearing and Prey Availability Affect American Kestrel (Falco sparverius) Reproduction?

Previous studies have indicated that over the past 20 years winters have warmed, but spring temperatures remain unchanged in southwestern Idaho. During this time, American kestrels (Falco sparverius) have advanced their nesting period by 28 days. Changes in nesting phenology may result in early-breeding kestrels raising young before important peaks in prey availability occur, while later-breeding kestrels may have a greater likelihood in raising young during peak prey availability. We hypothesize that the degree of synchronization with prey availability affects kestrel reproduction and predict that nesting events synchronized with prey availability will produce young in better condition than asynchronous nests. We used morphological measurements of nestlings gathered since 2008 from a sample area containing ≈ 120 nest boxes to assess condition. We calculated a synchrony index for each nest based on the clutch initiation date and annual patterns of NDVI, a predictor of prey abundance. We then used the synchrony index to predict nestling growth. As climate change continues to intensify, it is crucial to learn how these changes impact the reproductive success of wildlife populations.