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Back to News Updates – July 11, 2022

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Kestrels Take Flight at Mt. Cuba Center

The American kestrel, Falco sparverius, is the smallest falcon in North America, and an endangered species in Delaware. The grasslands and open habitats these birds require have rapidly disappeared due to development, and kestrel populations have plummeted throughout the Mid-Atlantic region in the last thirty years. The causes of American kestrel declines are the subject of active research.

Mt. Cuba Center collaborates with the Delaware Department of Natural Resources and Environmental Control (DNREC) and Delaware Kestrel Partnership to aid in conservation efforts for the American kestrel. Mt. Cuba actively manages its grasslands and meadows to further populations of kestrels and other species of conservation concern.

Grasslands and meadows produce numerous insects that kestrels and many songbirds require to feed their young and provide crucial habitat for ground nesting birds like meadowlarks. These habitats are not mowed at Mt. Cuba Center until late summer, after ground nesting birds have fledged, or left the nest. Additionally, these fields are not mowed every year; mowing is alternated with prescribed burns, and invasive weeds are spot treated with herbicides.

“Every wildlife species has its niche and this species needs wide open spaces, something that Mt. Cuba Center is providing them,” said Jordan Brown, DNREC’s raptor, grassland, and forest bird biologist. “The work that DNREC is doing and what Mt. Cuba is contributing to the project is important for kestrel conservation.”

A baby kestrel is held as it waits to be banded

American kestrels are cavity-nesters; they lay eggs and rear their young in preexisting tree holes, nest boxes, or other various small spaces (at times, even buildings). Kestrels may lack suitable cavities for nesting, and invasive species such as European starlings, Sturnus vulgaris, may outcompete them for available nest sites. Mt. Cuba maintains multiple kestrel nest boxes in the natural lands, and kestrels have been successfully nesting in these boxes for several years.

“By partnering with organizations like DNREC and the Delaware Kestrel Partnership to monitor nest boxes, we learn more about the response of American kestrels to land management practices at Mt. Cuba,” said Ellen Lake, Mt. Cuba’s director of conservation and research. “This allows us to make data-driven land management decisions. Additionally, data from these nest boxes are shared with state and national conservation organizations, enabling Mt. Cuba to contribute to broader data sets that are critical to learn more about kestrel biology and guide conservation efforts.”

Kestrel nest boxes are monitored throughout the state, and DNREC recently banded five chicks at Mt. Cuba before they fledged. Numbered aluminum and colored leg bands were placed on the kestrels to identify individuals. When a bird is recaptured or a colored band is spotted, scientists learn more about the age and movement patterns of individual birds, their habitat use, nest fidelity, and nesting success. The public can report sightings of numbered bands to the USGS Bird Banding Lab.

How to help:

Reports made by the public are an invaluable resource to researchers studying breeding and migratory activities, as well as suitable habitats. Kestrel sightings can be documented with eBird. If you spot the number on a colored leg band, report it to the USGS Bird Banding Lab . There are also opportunities to volunteer with the Delaware Kestrel Partnership.