Mysterious Declines: The American Kestrel

Cover photo: © Gregory “Slobirdr” Smith, 2007, some rights reserved.

Learn about North America’s smallest falcon and its mysterious decline across the United States.

Cover photo: © Gregory “Slobirdr” Smith, 2007, Flickr Photo Album, some rights reserved.

Places to See American Kestrels

Pearson-Arastradero Circle

Pearson-Arastradero Preserve

American kestrels are experiencing declines throughout the United States, including coastal California.

Data from the Peregrine Fund’s American Kestrel Partnership suggest that the coastal California population has been experiencing declines since the 1960’s.

Scientists do not know the “one true cause” of kestrel declines in the United States; rather, they believe that multiple causes could be working together to depress populations. Possible causes include habitat loss, the use of neonicotinoid insecticides, and local threats from the use of anticoagulant rat poisons.

Many local organizations are working to construct artificial kestrel nesting boxes to help the numbers in their area. For more information on how to construct a kestrel nesting box, check out this page by the Cornell Lab of Ornithology’s NestWatch.

American kestrels are North America’s smallest falcon.

They are about the size of a mourning dove, measuring in at 8.7 – 12.2 inches in length. Male American kestrels have beautiful slate-blue wings and rusty backs/tails. Females, on the other hand, are more subtly-beautiful – they have rusty wings and backs. Both males and females have black “slashes” on their faces.

You can often recognize American kestrels by looking for a bobbing head or tail. This charming behavior makes these birds distinctive on telephone wires, even at a distance.

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Male American kestrel; Source: © Matthew Buynoski, 2018, all rights reserved.

American kestrels eat large insects, small reptiles and amphibians, and even the occasional small bird.

American kestrels are raptors, meaning that they subdue and kill their prey using their feet. They hunt by swooping down on small prey and grabbing it in their talons.

Kestrels will sometimes cache, or store, extra food to keep it for later consumption or hide it from other animals.

American kestrels are secondary cavity-nesters, meaning that they build their nests in cavities excavated by other animals.

Once established at their nest site, female kestrels lay 4 – 6 eggs that are incubated by both parents. After about a month, the eggs hatch. The young and the female are fed by the male for a couple of weeks, after which the female leaves and begins to forage as well. The young begin to fly about a month after hatching.

Matthew_Kestrel
American kestrel at Pearson-Arastradero Preserve; Source: © Matthew Buynoski, 2018, all rights reserved.

Cool facts about American kestrels:

  • American kestrels are also known as “sparrow hawks” or “mousers”.
  • Only the northern populations of American kestrels migrate south during the winter. Central and southern populations are permanent residents.
  • American kestrels have a very distinct and excitable call, making these birds easy to locate by sound. To hear the American kestrel call, check out this page.

Resources to learn more:

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Male American kestrel in flight; Source: © Matthew Buynoski, 2018, all rights reserved.