As we gear up for the final breeding season of the Full Cycle Phenology project, here’s a look back at the 2019 breeding season.

Phenology Data Collection

From trail cam photos inside nest boxes and in-person visits, we collected timing information such as: the date kestrels arrived in nest boxes, when they laid eggs, when eggs hatched, and when nestlings fledged from the box. We conducted >1000 in-person nest box visits across Department of Defense (DoD) sites, and collected  >150,000 images from inside nest boxes over the 2019 breeding season.

Our team of research technicians and graduate students are currently going through thousands of images and recording data from each image (i.e. nest status; presence, sex, and count of adult kestrels, eggs, nestlings; incubation behavior) using the ViXen image processing program. These data will be used to understand the timing of breeding behavior and the consequences of timing on productivity and survival.

Kestrels occupied 49 of 242 nest boxes at seven of our 12 DoD sites in 2019 (
Figure 1), ranging from one occupied nest at Big Oaks National Wildlife Refuge, Indiana, to 15 occupied nests at Yakima Training Center, Washington. No kestrels nested at our DoD sites in Alaska, Texas, Florida, North Carolina, North Dakota, or California in 2019. However, we did have several other cavity-nesting species that used our boxes including: buffleheads, screech owls, bluebirds, tufted titmice, and several squirrel species! 

Figure 1. Map of American Kestrel nest outcomes in nest boxes on Department of Defense installations. Circles represent DoD sites where nest boxes were occupied, the size of the circle represents the total number of occupied boxes (ranging from 1-15), and the color represents the proportion of “successful” nests (i.e. where ≥1 nestling fledged) at that site, ranging from 0 (light blue; all nests failed) to 1 (dark blue; all nests were successful)


The majority of these nesting attempts (30/49) were “successful” (i.e. at least one nestling survived to fledging age). Most nest failures occurred at the egg stage (i.e. abandonment by adults or eggs predated), although a few failures occurred at the nestling stage (i.e. nestlings predated).

Genetic and Isotopic Data Collection

Using real-time information from cellular cameras and from communication with DoD biologists, our Boise State University crew conducted trips to DoD sites with nest boxes occupied by American Kestrels. We captured adult and nestling kestrels to attach unique identifying bands, take measurements, and collect genetic samples (from feathers) and isotopic samples (from claw clippings).

From April to August 2019, we banded and collected biological samples from 198 kestrels (56 breeding adults and 142 nestlings) across seven DoD sites (Figure 1). In addition, we collected samples from adult kestrels in southern Saskatchewan (n = 7), Canada, and from nestling kestrels in Fairbanks, Alaska (n = 2).

The combination of phenology data and biological sample data will be used to test relationships between genetic and isotopic signatures of individual kestrels and regional populations with the timing of breeding.

Stay tuned for more updates on our research as we head into the final breeding season of the Full Cycle Phenology project!

This research is supported by the U.S. Department of Defense, through the Strategic Environmental Research and Development Program (SERDP RC-2702).
Special thanks to the 19 DoD biologists and volunteers across 12 DoD sites who monitored nest boxes and provided invaluable on-the-ground help with logistics, camera troubleshooting, and species identification.
Post by-Anjolene Hunt

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