Last weekend, Ed, Nick and I traveled to the Alpena area one last time to band Kestrel nestlings. With Arnie Pokorzynski as our guide, we were able to band 20 nestlings, bringing our total to 103 Kestrels. One interesting highlight was discovering 8 eggs in one nest box. American Kestrels usually lay 4-6 eggs, so this clutch was quite large. Although we do not know with certainty, we hypothesize that a female Kestrel may have laid some eggs that for some reason she was unable to return to, at which time another female Kestrel may have taken over the nest box and laid additional eggs. We also banded our 100th Kestrel!
8 eggs in one nest box!
An exciting bird: the 100th Kestrel we banded! This male is approximately 24 days old and he has a bit of leftover food stuck on his beak!
Although these two Kestrels are from the same nest, the male chick on the left is older than the female chick on the right. Female Kestrels lay their eggs over a period of days, often laying a few eggs before beginning to incubate. The eggs will also hatch over a few days, which sometimes results in chicks from the same clutch exhibiting age differences.
Here we show the same chicks from a different angle. In terms of size, the female on the bottom is not much smaller than the male at the top. However, she has much more fluffy down and her feathers have not had as much time to emerge. We aged this female to be about 16 days old and her brother to be about 18 days old.
Today, July 7, we visited 2 nest boxes in Emmet County which contained nestlings that had previously been too young to band. Both boxes contained 3 young each, which brought our season total to 109 American Kestrels banded. Only 1 of the 109 was an adult. Today will likely have been our last day of Kestrel banding this summer.
A bittersweet bird: the last Kestrel to be banded, our 109th! This male is about 16 days old.
A dorsal view of our last Kestrel featuring our banding kit in the background. In the coming days, he will lose his white down while the feathers of his juvenile plumage lengthen and grow.
Another June weekend meant more American Kestrel chicks to band! On June 23, Ed, Nick and Frances travelled to the Alpena area once again to meet up with Arnie Pokorzynski. 28 chicks were banded. On June 24 we visited next boxes in Cheboygan and Emmet counties. We banded 5 more chicks. Several nest boxes we checked contained chicks too young to band. We will revisit these boxes in the coming weeks with the hopes of banding their inhabitants.
Aside from banding these Kestrels, one of our objectives has also been to collect data to contribute to the American Kestrel Partnership’s genoscaping project. This project aims to compile genetic information about Kestrels around America. To do this, we collect two breast feathers from one nestling per clutch, which will be sent to a lab to be analyzed. The goal is to create a map that geographically differentiates subpopulations of Kestrels based on base pairs found in their DNA sequence. This will better help us understand the specific migratory routes of different populations within the species.
Here we compare two nestmates. This photo illustrates the differences between female (the bird on the left) and male (the bird on the right) Kestrels. These nestlings are 23-25 days old and resemble miniature adults at this stage.
This female is close to fledging. American Kestrels leave the nest around 31 days after hatching, but parental care continues after fledging for about another week.
A few of the boxes we checked this last weekend contained chicks too young to band. We will wait until at least 13 days after hatching to band these chicks. This will give their feathers time to emerge and will allow us to determine their sex.
Ed, Frances and Nick work together to retrieve a clutch of 5 feisty chicks accompanied by Steve Baker and Kathy Bricker of MSRW. (Photo credit: Steve Baker)
As we gear up for another weekend of banding, we thought we would share some of the American Kestrel photos we have taken thus far.
Several of the nest boxes we checked in the last two weekends contained eggs or chicks too young to band. With Kestrels, waiting until at least day 13 after hatching allows feathers to emerge enough from the sheath for us to reliably sex them. It’s easy to sex the nestlings because males have blue-gray wing feathers while females exhibit a rufous color.
American Kestrel clutch sizes generally range from 4-6 eggs which the female Kestrel incubates for about 28 days.
This male nestling is about 18 days old.
At about 20 days old, this male nestling has lost a lot of down and the feathers of his juvenile plumage are quickly emerging!
Sometimes we have to climb ladders.
We are looking forward to checking on a lot more Kestrel nest boxes this weekend and will soon have many more photos to share!
Nick, Ed, and I holding a clutch of 5 nestlings after banding and collecting data on them.