The 2023 kestrel nest box season was another interesting year, showing that we can never be sure what the cycle of life has in store. Our Stewardship Director, Chris Volonte, shares the ups and downs of the 11th season of our American Kestrel Nest Box Project that provides more than two dozen specialized nesting boxes around our region.
Our experienced and dedicated volunteer crew made 193 visits to observe the 24 boxes managed by Kestrel Land Trust and also collaborated with Arcadia Wildlife Sanctuary to help them observe three occupied boxes at their sanctuary in Easthampton.
It was a mixed year, with low box occupancy and a predation occurrence that killed an entire clutch of chicks. On the other hand, there was a high chick hatching rate and a high overall number of chicks banded. In total, 46 kestrel chicks were banded during the course of the nesting season.
Based on our volunteer monitor reports, kestrels were seen on or near 10 out of 24 boxes managed by KLT. Based on direct box checks, 8 boxes were used by breeding pairs of kestrels. This is the lowest occupancy rate (33% of all boxes) we’ve observed since 2018 (35%), So far, our highest occupancy rates were during the years 2019 through 2022 with between 47%-58% of boxes occupied.
Every year we track successful versus unsuccessful breeding pairs – successful meaning the birds laid eggs and at least some chicks hatched and survived to banding.
Of 38 eggs laid, 35 hatched (92% of all eggs), the highest hatching rate since 2020 (93%). Of the 35 chicks, 30 were known to survive until banding. The chick survival rate was 86%, the lowest since 2018 (81%). This was due to a single predation occurrence at Box 8 (predator not identified). This was particularly disappointing to us since our team has been working hard to develop an effective predator baffle, and our new baffle was in place on Box 8.
However, just one failed box means 7 successful ones! Fortunately, all the other kestrel pairs raised all their hatched chicks to banding age. That’s 88% of occupied boxes. For perspective, during our 11-year project, 7 years have yielded a success rate of 80% or above, with 4 years at 71% or below.
In all, this year we banded 30 chicks hatched in KLT boxes, the 3rd highest number since the project began in 2013.
Additionally, at Arcadia Wildlife Sanctuary, 3 boxes were occupied, all of them successfully, and we banded 13 chicks with help from Arcadia staff.
Lastly, at mid-season a new box joined our ranks, when a Hatfield resident contacted us to let us know he had breeding kestrels in a box in his yard, and he was observing them daily via a nest box camera. Since he knew the exact date the chicks hatched, it was easy for us to target a banding window and swing by to band the 3 chicks. With the landowner’s continued cooperation and management of this box, we will hope for future years of success and more opportunities to band the chicks!
“D7” FEMALE RETURNS TO CONTE REFUGE
One of the most interesting events this year was the return of an adult female kestrel to Box 6 at the Conte Refuge. We found this bird in Box 6 and banded her in June 2020, giving her a field readable band with the characters “D7”. In June 2021, we found her in Box 6 again. This year, we not only found her in Box 6, but we were able to outfit her with a Motus radio tag (see below). Now wearing both bands and a tag, this female — who has likely occupied Box 6 every year since 2020 — will contribute information about her movements to a large-scale study of kestrel behavior. Read on!
This was the second year that KLT assisted MA state ornithologist, Andrew (Drew) Vitz, who is involved in a large research effort to determine the movements of American Kestrels using the Motus Wildlife Tracking System. This is an international collaborative research network that uses a coordinated automated radio telemetry array to track the movements and behavior of small flying animals. Researchers use tiny harnesses to fit small lightweight radio-transmitters on animals such as birds, bats and large insects. The signals are detected by receivers installed around the landscape. The data from these receivers is then centralized, analyzed, archived, and disseminated to all researchers and organizations in the network.
Last year, the folks at Arcadia Wildlife Sanctuary adopted KLT’s pole camera technique for box checks, and as a result of their box monitoring, a male kestrel was fitted with a radio tag at Arcadia in late June 2022. This year, KLT was able to connect Drew with three sites (Box 6, Box 14, and Atkins Flats Conservation Area in Amherst) where he was able to safely net adult kestrels (2 females and 1 male) to be outfitted with a tag.
If you would like to see the data on these three kestrels (and others) on the Motus site, one place to start is the Tag Deployment page for the Massachusetts project. Scroll down to ID#s 47340-47342 (dated 6/5/2023). From there, you can click on each ID# to see the detail page on that bird. On that page, you can use “Show detections” to select from three data views: table, timeline or map. Learn more about MOTUS and see more details here.
FIELD READABLE BANDS
Many of the kestrels we band are given “field readable” bands. These are larger bands with 2 characters (letters and numbers) that are meant to be read from a distance. As you continue birding in the area, please keep an eye out for kestrels sporting large green bands, and be sure let us know if you spot one! Close up photos sometimes reveal the band characters, which may help us identify an individual kestrel from our study!