The American Kestrel

Photo: American Kestrel, Mick Thompson/Audubon Photography Awards

Evelyn Novins

The American Kestrel, Falco sparverius, sometimes erroneously called a sparrowhawk, is found throughout North America. The misnomer likely arises from confusion with the Eurasian Sparrowhawk, another bird that likes open hunting grounds with high perches from which to spot prey. But the sparrowhawk is an Accipitor, and the kestrel is not a hawk but a falcon, as evidenced by its flight profile, with its characteristic pointed wings and long, narrow tail. American Kestrels are often seen perching on utility wires alongside farm fields, or hovering with rapid wingbeats, until dropping to snatch prey from the ground or mid-air. This robin-sized falcon is speedy and fun to watch.

American Kestrel female, Christopher Ciccone/Audubon Phtography Awards

American Kestrel male, Mick Thompson/Audubon Photography Awards

The Audubon Field Guide identifies black, blue, gray, red, brown, white and yellow on the body of the American Kestrel. The male’s blue/gray-colored wings distinguish it from the slightly larger female, which has red/brown wings. Both sexes have brownish backs and buffy-white, or off-white, undersides with a black flecking, as well as two dramatic, black slashes running down from the eye. The female has black barring on the wings and back with a red/brown cap. The male’s cap is dark grey. It is a colorful bird with noticeably yellow feet.

The American Kestrel generally inhabits any kind of open area from farmland and forest clearings to deserts -- wherever it can find abundant prey and some raised perches. In breeding season, it must be near places with appropriate nesting sites. The kestrel is a cavity nester; however, it does not make its own cavity, relying on abandoned woodpecker holes, natural cavities in trees, or rock cervices. The good news is that these secondary cavity nesters will readily nest in man-made boxes with unobstructed entrances. 

Fairfax County has maintained several capped mounds at the I-95 Landfill Complex as grasslands and meadows, attracting Eastern Meadowlarks, Bobolinks, and other grassland-loving birds and insects to the area. The American Kestrel, which favors this kind of open space for hunting, is frequently seen in this area. To further conservation efforts, landfill managers also recently set aside a portion of the 500-acre landfill as a “no mow” area, with the aim of increasing high-quality meadow habitat that should attract a variety of grassland birds. To encourage American Kestrels to nest in the area, NVBA has contributed several nest boxes, which the County has erected at the landfill.

The last 10 years have seen a steady decline in the numbers of this species. Habitat alteration, pesticides, and predation by Cooper’s Hawks all have been cited as contributors to the decline. But there is increasing recognition that to understand the decline in population of the American Kestrel and other birds over the last decade scientists must look at the species’ total life cycle. The growth of information on species’ migration, available through the free, interactive, online Bird Migration Explorer, is evidence of that focus.

The Kestrel is a migratory bird, but with only a short, southern migration. Breeding birds from Canada and some northern states migrate to southern states during the winter season. Scientists are now paying attention to its migration stops and wintering habitat in addition to its breeding habitat to understand its population decline. The Clifton Institute's research gathers this whole life cycle information. Together with the Smithsonian Conservation Biology Institute, the Clifton Institute has tagged 19 kestrels with GPS transmitters to assess what type of grassland areas the birds prefer while breeding and while migrating.  This project produces results which landowners, land managers, and conservationists can use to support declining species. 

So, despite the decline in Kestrel numbers in the past decade, there is some hope that both local and global conservation initiatives will allow our continued enjoyment in observing the lovely and lively American Kestrel.

Spend Some Time with the Bird Migration Explorer—You Won’t Be Sorry

Photo: American Kestrel, Matt Felperin

Fall migration through northern Virginia is by no means over, but the numbers of birds traveling to, as well as passing over and through, our area is on the decline. Some of us may now stop obsessively checking BirdCast daily to see what we may anticipate passing through overnight. But, that doesn’t mean that we should stop obsessing about migration and the challenges it presents to North American birds. 

The last few years have seen an explosion of data collection and data management tools that are giving us a more detailed view of migration than we have ever had before. The Bird Migration Explorer is an online guide to the journeys of 458 species of birds generated from data consolidated from multiple sources. It is available as a free interactive platform through National Audubon Society, but was developed through a partnership among Audubon and Birds Canada, Bird Conservancy of the Rockies, Bird Genoscape Project, BirdLife International, Cornell Lab of Ornithology, Esri, Georgetown University, Movebank, and the Smithsonian Migratory Bird Center.

Spend a little time on the site and you can see what information is available and how the information can help focus conservation and advocacy efforts in the North America. 

Look, for example, at the maps for the American Kestrel, a bird facing significant challenges in our area because of vanishing meadows. The base map that underlies the migration and connection maps shows the bird’s summer, winter, and year-round ranges, information that is generally available from field guides, both printed and online. That data for the explorer comes from eBird at the Cornell Lab, BirdLife International, and Audubon. 

American Kestrel, Matt Felperin

But the migration map provides more. Overlaid on that base, using information from the same sources, is a graphical representation of abundance of the species throughout the yearly cycle. While the map shows moderate abundance in some areas of the country, it clearly shows the perilous state of the bird in our area. And what seems almost magical, the map includes the route of tracked birds: the routes are generated from two studies that tracked 10 individual birds, data shared by researchers and stored on Movebank and Motus. There’s also a link to a 2020 article about the species’ decline. 

But there’s even more! Species connection maps show where tagged birds of one species have been re-encountered as they traveled across the hemisphere. Connections are derived from millions of re-encounter observations from tracking, banding, automated radio telemetry, and genetics data. A mouse click on a location displays the locations the species traveled to and the number of individuals that have traveled between the locations. The map shows birds from our area showing up further up the coast into Canada, down to the east coast of Florida, and inland to Georgia. The kestrel map shows connections for 1,943 individual birds, data from four studies stored on Movebank, the USGS Bird Banding Lab, Motus, and the Bird Genoscape Project. 

But how does all this information help direct our conservation efforts? Click over to the conservation challenges maps and look for our area. The data for these maps come from weekly distribution data from Cornell’s eBird. The map provides a visual image of different challenges in the area throughout the year. Conservation challenges such as suburban development, roads, and power lines fluctuate in intensity during the year depending on the relative abundance of birds in the area—showing higher exposure and higher abundance during migration as birds pass through our developing landscape. 

The data indicate that ASNV’s current focus on conservation and advocacy efforts is appropriate—that is, a focus on preserving and maintaining habitat, supporting wildlife corridors and responsibly sited bike paths, creating bird-friendly habitat in developed areas, encouraging developers to use bird-friendly glass in construction, educating the public about turning off lights during migration, and working to limit exposure of birds to predation by free-roaming cats. Those efforts can help our local wildlife as well as vulnerable migrants. 

Another takeaway from the exercise of exploring the Bird Migration Explorer is the importance of citizen science to bird conservation. Identification of the relative abundance of birds throughout the calendar year and throughout the Americas provides the base for the migratory bird initiative. Continuing development of citizen science data, as well as analysis of the available data over time, also can show important trends that can further focus all of our efforts.

On the issue of changing trends over time, you can look forward to an article in next month’s Potomac Flier on the recently-updated State of the Birds Report 2022 (released on October 12, 2022). The report is available at StateoftheBirds.org. Until then, take a look at this month’s “President’s Corner” on how ASNV can use multiple data sources to focus its efforts on behalf of the birds and our local environment.

Enjoy exploring!