An American Kestrel

Since 2014, The Brandywine Zoo has pioneered an American Kestrel Nest Box research project across the State of Delaware.  The Brandywine Zoo became the first AZA organization to join forces with the American Kestrel Partnership in 2014, and to date has more than 50 Kestrel nest boxes across all three counties that are monitored with a small team of researchers and citizen scientists.

What Are Kestrels?

Kestrels are the smallest species of falcon. The easiest way to spot a kestrel is by observing their hunting behavior: when hunting, the kestrel will hover at a height of about 10-20 meters, a behavior called “kiting,” before diving down on its prey. They typically hunt small mammals and insects, but may occasionally take small birds and lizards using this method.

Kestrels are also noteworthy because of their ability to hover in the slightest of winds. They do this by positioning themselves like a kite in order to make the most efficient use of the wind as possible. Kestrels have been known to hover even when they are inside due to this ability.

Kestrels are secondary cavity nesters, meaning that rather than building their own nests, they will make use of empty cavities in trees left by woodpeckers. They will even nest in cavities in human structures like buildings or barns and will readily use man-made nest boxes.


The American Kestrel

The American Kestrel is the only species of kestrel in North America and is the smallest species of falcon on the continent. American Kestrels are recognized by their colorful plumage and unmistakable moustache stripes under each eye.  Although it is listed federally as “Least Concern”, the American Kestrel’s population in the Mid-Atlantic has decreased by 88% since the 1960s, according to the North American Breeding Bird Survey.  There are many theories into the American Kestrel’s decline, such as West Nile Virus exposure, loss of suitable habitat, increased predation by Cooper’s Hawks (Accipiter cooperii), pesticide accumulation, or some combination of factors. Despite the abundance of research being done nationwide, a comprehensive cause for the decline has not yet been established.  More research is necessary in order to pinpoint the principal cause(s) and attempt to conserve this small falcon’s species.

The American Kestrel in Delaware

In Delaware, the American Kestrel is listed as a State Endangered Species. Kestrels in Delaware experienced more than a 60% decline between 1987 and 2012, leading to the down listing to their Endangered status. Here at the Brandywine Zoo, we are dedicated to the conservation of this beautiful species and are working with multiple organizations to protect and study it in Delaware. The Brandywine Zoo is the founder of the Delaware Kestrel Partnership (DKP), a multi-organizational partnership of governmental and nonprofit conservation organizations. Through the DKP, we collaborate, share data and information, and pool resources in order to make our conservation efforts more efficient.

The ultimate goal of the Delaware Kestrel Partnership is to determine a probable cause of decline in Delaware’s American Kestrel populations by; conducting demographic studies which utilize the guidelines of the American Kestrel Partnership, unifying citizen and professional science data, and educating the general public on American Kestrels and ways to help increase their population.  With the additional help of citizen scientists, the researchers in the DKP are able to collect this data and share it as a group not only internally but also with the Peregrine Fund’s American Kestrel Partnership Program, a national citizen science research program. An additional goal of this project is to educate the public about the decline of kestrels in Delaware and how citizens can help.

Why Is It Important to Study American Kestrels?

American Kestrels provide an important ecosystem service to humans: rodent and pest control. Their diet of rodents and insects, however, puts them in a precarious position that leaves them sensitive to pesticide accumulation and exposure to rodenticides.  As a result, Kestrels can potentially act as indicators of the overall health of the entire ecosystem. While it is unclear exactly why American Kestrel populations are declining across the country, it should be taken as a serious threat to the health of humans, Kestrels, and their habitats alike. With the data we collect from monitoring nest boxes and banding kestrels, we hope to be able to answer fundamental questions about American Kestrel demographics and provide insight into land management decisions that may benefit Kestrels and other wildlife.

Why Is Conserving the Ecosystem Important?

Healthy ecosystems benefit not just the wildlife that live there, but also the people who live in and around them, too. Nature is full of checks and balances, and small disruptions can result in major systemic problems. It is critical for wildlife researchers to understand the dynamic relationships between ecosystems and the wildlife that live there in order to better ensure that humans and wildlife can co-exist or even benefit from one-another. Long-term monitoring like that of our Kestrel Nest Box Project is essential for understanding how patterns of wildlife distribution and population dynamics change over time in the face of increasing urbanization, altered land use, and emerging disease risks.

We have so much to learn from the study of plants and animals and we owe it to future generations to preserve the diversity and natural beauty that our planet has to offer.

Have You Seen This Bird?

Have you seen American Kestrels in Delaware? We want to know! On our DKP page, we have lots of information that will assist you in accurately identifying the American Kestrel as well as how to report them.

If you have seen a Kestrel, you can contact us directly or log your sighting on, where we will be able to access any public sightings. With your help, we are able to identify where Kestrels are still located in the State and potentially identify nearby sites that would be appropriate for a nest box.

Help our conservation efforts now: Delaware Kestrel Partnership