Study Shows Climate Affecting Avian Breeding Habits
Milder winters have led to earlier growing seasons and noticeable effects on the breeding habits of some predatory birds, according to research by Boise State biologists Shawn Smith and Julie Heath, in collaboration with Karen Steenhof, and The Peregrine Fund’s Christopher McClure. Their work was recently published in the Journal of Animal Ecology under the title “Earlier nesting by generalist predatory bird is associated with human responses to climate change.”
Smith and his co-authors studied the American kestrel (Falco sparverius), also known as a sparrow hawk, because the bird is widespread and responsive to environmental change. Their question was whether the warming climate had led to changes in prey abundance and a corresponding change in when the birds nested.
Their study looked at kestrels that nested in both non-irrigated shrub and grasslands and those that nested in irrigated crops and pastures. Using data from remote satellites to determine the greenness of different types of vegetation they were able to determine the start of the growing season for different areas. That is important because peaks in vegetation greenness correspond with peaks in kestrel prey, like small mammals and insects. They then looked at how that matched up with kestrel nesting patterns.
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Image courtesy: Rob Palmer