The 2014 Nesting Season
During the past twenty nesting seasons, 920 American Kestrels have fledged from nestboxes mostly located in the northern third of Delaware County. Several boxes are located just over the county’s border with Marion and Morrow counties. In 2014, the small falcons raised 61 fledglings from 13 successful nests after 16 nesting attempts with eggs. Along with several disappointments, the season’s production was the lowest during the last eight years, but once disappointments are analyzed, knowledge gained usually tempers most negative outcomes. Two events stand out and deserve attention: a somewhat disturbing band recovery and a fascinating forensic investigation, but first, a description of the project.
Dick Phillips and I monitor and maintain 18 kestrel boxes that make up the project that started in 1993 after schools in Delaware County, the Ohio DNR, county and state agencies, and the Delaware County Bird Club united to help our smallest falcon. The first successful nesting took place in 1995. Today, all but one box hang from utility poles belonging to the Consolidated Electric Cooperative, Inc., and Box K-16 is found on its own pole in Gallant Woods Preserve off of Buttermilk Hill Road.
On March 14, Dick and I monitored all of the project’s boxes to check on the status of their bedding. Starlings will excavate bedding before they build their own grass nests, and we added white pine bedding to two boxes that needed it. Later in the season, whenever we find a starling nest, we remove its eggs, but we never remove the grass nest itself. If a kestrel has already taken over the box, in time, the kestrel will reshape the starling’s round nest cup into an elliptically shaped cup. By leaving the starling nest, there is no chance that we will spook an interested kestrel from nesting. In 2014, we removed eight clutches of starling eggs from three boxes.
After the first days of April, we check the boxes every two weeks until the earliest eggs begin to hatch, then I use my extremely visual data sheets along with photographs in the booklet, A Photographic Timeline of Hawk Mountain Sanctuary’s American Kestrel Nestlings (available from Amazon.com), to age the nestlings in order to extrapolate their first-egg-dates and their subsequent ages, between 14 and 24 days, when nestlings will be most ready for accepting leg bands without drawing blood from their caretakers. Once optimum banding dates are calculated, we visit eligible families every week to band and sex feisty nestlings. Between May 30 and June 27, we banded 14 families, in addition to one kestrel family at the Stratford Ecological Center, during five weekly trips.
One family of two nestlings failed after banding. Three of five eggs had hatched in K-3 but only two occupied their nest to be banded, and they felt underweight. The next visit found them dead with no evidence as to why. The reason for their failure remains unknown, although a Red-tailed Hawk was a local resident and was seen on multiple occasions as it perched several hundred yards away.
Two nests failed while holding eggs. After one of the nests failed, both kestrels disappeared since a pair of Eastern Bluebirds claimed the box. We attached a bluebird box’s front panel to the front of the kestrel box in order to reduce the three-inch entrance to 1-1/2 inches so the bluebirds could be kestrel-free while raising three young.
The other failed nest held five infertile eggs. We checked K-2 thirteen times during the season and found a parent on eggs eight times between April 17 and August 3. The female was found incubating four times, and the male was recorded four times. Finally, during our last trip of the season on September 9, when we lowered all boxes to replace old bedding with new, we broke K-2’s spoiled eggs and found no embryos.
In the future, I would like to deliver unhatched eggs to a curious organic chemist for analysis. From what I have read, our modern world is becoming more toxic, and birds have always been good indicators of what is also attacking our species.
Because of many weather-related factors, the 2014 kestrel nesting season was stunted at both ends. During the 2014 season, no eggs were laid in March, and no clutches were started beyond April 30. The record dates for earliest first-egg-dates are March 14 in 1998 and 2012, and the latest first-egg-date recorded is June 25, 2011. Kestrels begin incubation once the next to last egg is laid, and incubation duties are shared for 30 days. After hatching, nestlings can be brooded for their first ten days and a family fledges thirty days after hatching. The 2014 kestrel season lasted 94 days from the first egg on April 3 to the last fledgling on July 5.
Clutch sizes in 2014 were fairly typical. Out of 15 completed clutches, 14 (93.3%) were five eggs and four eggs made up one clutch (6.7%). Not since 2010 have six eggs been laid, and in 2006, three clutches of six were part of the season, a sign of habitats loaded with excellent food resources in the form of mice, voles, small snakes, insects and small birds.
Kestrels laid 78 eggs in 2014, 66 (84.6%) hatched and 61 (78.2%) fledged. Five nestlings died while 92.4% of hatchlings matured to fledge wearing leg bands.
A Fatal Dispersal
Leg bands confirm that conservation is working when your project’s birds are found beyond the immediate area of your efforts. On 30 August 2014, my computer’s mailbox held an email message from the Bird Banding Lab in Silver Spring, Maryland. One of five kestrel fledglings from a box on Whipple Road was found dead in Cleveland, Cuyahoga County, Ohio. It had dispersed more than 100 miles to the Northeast before being found dead on July 24, 38 days after it had flown from its natal nest. The finder, an employee of the U.S. Department of Agriculture, reported the band number and other information to the banding lab.
On the report form to the bander, “Encounter Information” is given in the form of numbered codes that are listed in manuals and on the lab’s website. Under “How,” the code number 44 is defined as “Caught or found dead due to: control operations (roost bombing, gassing, avicides, wetting agents, etc.).” I sent an email to the finder thanking him for reporting his find and I asked for his phone number so I could call and gather more information. I got no reply. So, for now, I have nothing more to report.
A Forensic Investigation Yields Information
And now, for some good science. On May 30, we banded five kestrel nestlings from K-18. As is our practice, after banding a family, we find no need to check the box until we know the family has fledged. On July 5, we inspected the empty nest to find a pair of wings, still attached to dry tissues. The wings were completely covered with fecal whitewash, and our initial thought was that one of the kestrel nestlings had died and its siblings recycled its flesh, a common practice among raptors. We did not have our equipment needed to lower the box to the ground, but a preliminary search of the nest turned up no leg remains with a band attached. We had to wait weeks for a complete search for remains when we replaced the box’s old bedding with new.
On September 9, we thoroughly searched through K-18’s old bedding and found nothing. Therefore, the wings did not belong to a kestrel. It is common for kestrels to field dress birds by removing heads, skinning their bodies, and eating body parts before delivering edible remains to their young. So, whose wings ended up inside Box K-18?
In anticipation of a meeting of the Delaware County Bird Club scheduled for September 22, I washed the wings with some Dawn dishwashing detergent and blasted them with a water hose to find their feathers mostly black, not slate gray like a male kestrel’s. I still had no idea what species they belonged to, so I put the wings into a plastic bag and took the specimens to the bird club meeting where I hoped serious birders would use their expertise to identify the wings.
When Rich Bradley inspected the wings and heard the story of their finding, his scientific mind came up with the best plan. The next day, he took the wings to OSU’s Museum of Biological Diversity on Kinnear Road in Columbus where he compared the wings to study skins in their collections, and a match was made. Rich sent me an email announcing that the wings belonged to a Greater Yellowlegs.
A set of possible answers, and more questions came to mind. A soybean field directly across the road from K-18 had several bare spots that might have been caused by a failed field tile that enabled standing water to drown soybeans while enticing a non-breeding Greater Yellowlegs to land. If a kestrel did not harvest a live, vigorous shore bird, then did the yellowlegs become sick from crop dusting in the area, or was it a victim of road traffic? We will never know.
There is more kestrel news to report, such as kestrels that finally nested in the Althea Sherman Barn Box at the Stratford Ecological Center, but that report will come later. For now, I will follow through with my state and federal salvage permits, and I will deliver the Greater Yellowlegs remains identified by Rich Bradley to the Ohio Wesleyan Zoology Museum. Perhaps, a challenging forensic investigation will be repeated as part of a future lab exercise at OWU. Raptor on to 2015!