Facts about the American Kestrel FALCON SPECIES:
American Kestrels are the smallest species of falcon in North America, weighing 3-6 oz and with 20-24 inch wingspans, they’re only a little larger than a robin (“American Kestrel” 2014). Kestrels are the second smallest falcon in
the world – the smallest is the African pygmy falcon (
Polihierax semitorquatus). There are seven falcons found in North America and five that can be seen in Washington State. In order from largest to smallest, these are the Gyrfalcon
( Falco rusticolus), the Peregrine falcon ( Falco peregrinus), the Prairie Falcon ( Falco mexicanus), the Merlin ( Falco columbarius), and the American kestrel.
Kestrels have predominantly pale brown undersides, with reddish brown back and gray heads. Male and female kestrels are sexually dimorphic, an uncommon trait among raptors. Female kestrels have strong black barring on their back and wings, with a
lighter brown barring on their chest and multiple black bands on their tail. While male kestrels have slate-gray wings, black spots on their back, wings and body, and a single sub-terminal black band on their tail.
Since American Kestrels occupy such a wide range, there are multiple variations in plumage, behavior, preferred diet, and size between locations. Currently up to 17 different subspecies of American Kestrel are recognized throughout the Americas (Smallwood
and Bird 2002). In the wild, kestrels often only live 3 years, but have been known to survive up to 11 years in rare cases (Steenhof and Heath 2009; Smallwood and Bird 2002).
HABITAT & RANGE:
Kestrels are present year round throughout the United States, Central America and most of South America (Smallwood and Bird 2002). While Kestrels are fairly adaptable, they prefer open habitat with short vegetation and sparse trees. They’re
often found in grasslands, deserts, forest edges or clearings and alongside humans in cities, farmlands parks, near highways and in suburbs (Stys 1993).
HUNTING BEHAVIORS & DIET: With such a wide range, Kestrels have a wide and varied diet depending on where they live. Everything from grasshoppers to squirrels may fall prey to it. Usually kestrels will focus on small animals such as grasshoppers, dragonflies, small birds or voles during the summer months and during the winter they shift to small rodents like voles or mice (Smallwood and Bird 2002). Kestrels have several methods of hunting, but their preferred method is waiting on a high perch, such as a tree or powerline and swooping at prey. If there’s no perch then Kestrels may hover over a field instead. MATING & NESTING:
American Kestrels are seasonally monogamous raptors, normally taking a different mate each breeding season (Steenhof and Peterson 2009). Kestrels nest in cavities, either naturally made crevasses, cavities made by other species like woodpeckers, or
human made cavities like nest boxes. 4-5 eggs are laid from May to August depending on what latitude the kestrel is at, and they are then incubated for about 30 days before hatching (“American Kestrel” 2014). In another 30 days the
young kestrels will be ready to fly for the first time, and 2 weeks after fledging they’ll be mostly independent of their parents (Smallwood and Bird 2002).
Kestrel vision is thought to be between 8 and 12 times sharper than ours. To put that in perspective, if you were to attach a piece of paper with writing on it to a wall and walk as far from it as you can while still being able to read the words,
a Kestrel would be able to go 8 to 12 times farther away, and still be able to read it! This is because their vision is much sharper. Kestrels can also see in the ultraviolet (UV) range, and use this adaptation to track down prey by detecting
reflective urine trails left behind.
IDENTIFYING CHARACTERISTICS: Kestrels, like all other falcons, have distinct physical features that are not found in other raptors. These include; the falcon’s tooth, malar stripes, distinctly
pointy wings, and nasal tubercles. The falcon’s tooth is a small projection in the upper beak, just behind the tip, that fits neatly into their prey’s vertebrae making it easy to snap and quickly kill their prey. A corresponding notch
in the lower beak complements the "tooth". Long, pointy and narrow wings enable them to fly at high speeds. Kestrels in a stoop dive (a near vertical dive) can reach speeds of up to 60mph (Peregrine falcons can nearly quadruple this, reaching
speeds of over 200 mph!). Nasal tubercles are small bones found in the nose that allow falcons to breathe easier during high speed diving. Since kestrels are diurnal (hunting during the day), the dark malar stripes on the face help reduce glare
from the sun. SOURCES:
“American Kestrel.” 2014. Audubon. November 13, 2014. https://www.audubon.org/field-guide/bird/american-kestrel
Smallwood, John A., and David M. Bird. 2002. “American Kestrel (Falco Sparverius).” Edited by A. Poole and F. Gill.
Birds of North America. https://doi.org/ 10.2173/bna.602
Steenhof, Karen, and Julie A. Heath. 2009. “American Kestrel Reproduction: Evidence for the Selection Hypothesis and the Role of Dispersal.”
The Ibis 151 (3): 493–501.
Steenhof, Karen, and Brite Peterson. 2009. “Site Fidelity, Mate Fidelity, and Breeding Dispersal in American Kestrels.” Stys, Beth. 1993.
The Wilson Journal of Ornithology. https://doi.org/ 10.1676/07-177.1
Ecology and Habitat Protection Needs of the Southeastern American Kestrel (Falco Sparverius Paulus) on Large-Scale Development Sites in Florida.