Kestrels in Ulster County, NY. - Start of 2017 Breeding Season




American Kestrel (Falco sparverius) populations in the northeastern US have undergone significant declines over the past few decades. Both migration counts and breeding data are trending downward and the reasons are not well understood. Throughout much of the northeast, open habitats are reverting to forest, which is decreasing the available breeding habitat for kestrels. Additionally, natural nest sites are at a premium since kestrels need cavities surrounded by open habitat. Nest boxes compensate for this nest-site scarcity and the birds often prefer them when available.

In 2016 I initiated intensive monitoring of several nest boxes in Ulster County, NY. Six boxes are located on the Shawangunk Grasslands NWR (SGNWR) northwest of Walkill and one is located on the Mohonk Preserve west of New Paltz. The SGNWR boxes have been regularly monitored in recent years, but no concrete data on reproductive success have been collected. I visited boxes at least every two weeks from early March through June to assess occupancy, determine nesting phenology, count eggs and nestlings and eventually band the nestlings. Across all boxes, I observed the following – an average clutch size of 5 eggs/observed clutch; an average brood size of 4.5 nestlings/observed brood. Two boxes produced 6 young each, which is an unusually high output. 


Nest box, Shawangunk Grasslands NWR

With a generous lumber donation from ProBuild in Rosendale, NY, expert box construction by folks at Mearns Bird Club in Orange County, NY. and John Burroughs Natural History Society in Kingston, NY, I am able to continue and expand this project to 25 boxes throughout Ulster County in 2017. Other local cooperators include Mohonk Preserve, SUNY New Paltz, Hudson Valley Farm Hub, Whitecliff Vineyards and Walkill View Farm Market. Several private landowners generously allowed me permission to mount and monitor boxes on their properties. 

On a grander scale, I am cooperating with the American Kestrel Partnership (AKP) in Boise, Idaho (www.kestrel.peregrinefund.org), a continent-wide project addressing large-scale kestrel population declines in North America. One facet of this project is to be a clearing house for kestrel nest box data across the continent. All of those reproductive data such as nest occupancy, nesting phenology, clutch and brood sizes, fledging success, etc. are important to get a picture of how these birds are doing. 

Another exciting project is the American Kestrel Genoscape Project, a collaborative effort between the AKP, Boise State University and UCLA. Researchers are working to create a "genoscape map" of North American kestrel populations, which will hopefully give us the power to connect breeding, migration and wintering areas for different breeding populations. Feather samples are collected from nestlings across the breeding range and submitted for genetic analysis to create the map of the different populations. Then others working at migration and wintering areas collect samples from birds and submit these for analysis and comparison with the breeding season samples. This technique has some great potential value for conservation of many species. 

Monitoring boxes has begun for the season and many of them are occupied by kestrel pairs. In addition to nestling banding later in May and June, I aim to capture as many breeding adults as possible and put field-readable (VID) bands on them for easy re-sighting. See photo below. If you are out and about birding in Ulster County, or anywhere in the eastern US, keep an eye open for these bands. I am very interested to see where these birds go for the non-breeding season.


Recently banded Female

In the coming weeks, with help from SUNY students and a small number of volunteers (Thanks Laura, Troy, Joe and Clay!) boxes will be checked at least weekly for signs of breeding activity. We will be trapping adults as time permits. I will post updates on box status, trapping activities and anything else that comes up. ¡Viva Cernicalos!

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