AMERICAN KESTREL FALCON
SCIENTIFIC NAME
Falco
sparverius
CLASSIFICATION
Class:
Aves
Order:
Falconiformes
Family:
Falconidae
Genus:
Falco
Species: sparverius
The
American Kestrel has been nicknamed the “Sparrowhawk”.
Other nicknames include the Killy hawk, the Wind Rover, and the
Grasshopper hawk.
Length:
Male:
8 3/4 - 10 1/2 inches
Female:
8 3/4 - 12 inches
Weight:
Male: 90 - 120 grams
Female: 90 - 165 grams
Wingspan:
Male: 19-24 inches
174-198
cm.
Female: 19-24 inches
178-207 cm.
This
falcon is one of the few true birds of prey whose sex can be determined by
coloration. The male has
bluish-slate gray on top of his head with a ferruginous (chestnut) crown and
bluish-slate gray wings. The back
is almost completely ferruginous. They
have a whitish breast, suffused with light amber-brown, and under parts spotted
with black. The tail is red with a
black sub-terminal band and white tip.
The
female’s back, wings, and tail are broadly barred with ferruginous and dark
brown. They lack the bluish-gray on
the head and wings that the male has. The
under parts are white streaked and barred on the flanks in cinnamon, along with
a brown spotted breast and abdomen.
Both
have a black patch or stripe on their white face that extends from the eye to
the throat with another across the ear. The
beak is blue-black. The cere, legs,
and feet are yellow to yellow-orange. This
color is paler in the females and the juvenile birds.
The
juvenile coloration is similar to the adult, but more spotted or barred.
The juvenile male’s back is slightly darker and completely barred.
The tail is tipped with ferruginous not white.
The under parts are streaked and spotted throughout. The juvenile female has less conspicuous ferruginous
streaking on the head. The back is
darker with heavier black barring.
The
American kestrel keeps the juvenile wings, tail, and part of the body plumage
through an incomplete molt starting in September or October of the first year.
They do not lose these feathers until their second annual molt.
At two years (or by the spring of their third year), the immature birds
are indistinguishable from the adults.
The
American kestrel exhibits all the usual falcon characteristics:
•
Raptorial feet that are highly adapted for grasping their prey and very
long toes.
•
They lack the powerful spasmodic clutching mechanism of other birds of
prey.
•
Rather short beaks and jaw muscles modified to deliver powerful bites.
•
Tomial tooth (killing tooth), that is a notch on the cutting edge of beak.
•
Nostrils that possess a prominent central bony tubercle.
•
Long, pointed, distinctively proportioned wings.
•
Dark eye stripe or patch.
In
the wild:
8 -10 years
In
captivity:
10 - 13 years
RANGE/DISTRIBUTION
American
kestrel falcons are very widespread, ranging throughout the Western Hemisphere.
They are found from above the Arctic Circle in Alaska and northwestern
Canada, south through Canada and the United States, into Mexico, parts of
Central America, and most of South America.
In
fact, the American kestrel is the smallest and most common falcon in this area.
HABITAT/TERRITORY
SIZE
American
kestrels occur in a variety of habitats from sea level or below up to about
3,700 m (12,000 ft.) in the Rockies.
They
require open ground for hunting and are most often found in habitats such as
mountain meadows, marshlands, grasslands, deserts, open pine forests, and any
kind of mixed woods or grasslands, agricultural land, vacant sites, airfields,
along the edge of highways, etc.
American
kestrels usually defend a territory of approximately half a square mile.
The
migration patterns of the American Kestrel are not great although they are
slightly neotropic. They are found
as far north as the upper Yukon and middle Alaska and as far south as the Gulf
states in the spring and summer months.
During
the winter months, they migrate down to British Columbia and as far south as
Panama.
Those
kestrels that are found in the northern range, above latitude 45 degrees north,
are highly migratory. Those south
of 35 degrees north are mostly year-round residents.
Prey
consists mostly of small rodents, reptiles, insects, and an occasional small
bird hence the common name of "Sparrowhawk."
American
Kestrels have been photographed killing prey as large as a wood rat!
HUNTING METHOD
American
Kestrels hunt by openly skimming over the countryside or "hovering"
over a spot in a meadow or field waiting for their prey.
BREEDING INFORMATION
Most
do not gain access to a mate and nesting territory until they are two years old.
Males
tend to establish their nesting territory first, then the females join them.
At first, the females are loosely bonded to a particular mate.
They move about between two or more males before settling down with one.
Courtship
is simple and consists chiefly of aerial maneuvers and noisy cries by the male
in the pursuit of the female. American
kestrels have been seen first to mate with the birds facing one another and
slowly bobbing their heads and tails while the female keeps up a continuous low
call.
Kestrels
prefer tree cavities as nest sites, but will also use potholes or crannies in a
cliff, enclosed space in a building, or an abandoned nest from another bird.
They will also readily accept nesting boxes.
The availability of suitable tree cavities may be the chief
density-limiting factor on breeding populations.
Since they do not make their own holes, they depend on natural cavities
or holes built by other birds; and, as a result they have to compete with
woodpeckers, owls, squirrels, etc.
Courtship
behavior usually begins with the onset of spring. After mating, the male brings
the food to the female in the nest; and she begins to cache the extra.
Depending on their range, eggs may be laid from mid-April through early
June.
The
female will lay 3-7 buff with reddish-brown marked eggs but typically 4 or 5 are
laid. Incubation lasts about 30
days, and the young begin to fledge at 27-34 days.
The
cry of an American kestrel is a fairly high pitched "qui, qui, qui" or
a short, shrill chatter "ki-wee, ki-wee, ki-wee."
American
kestrels are able to hover. Many
birds can hover for a short period of time, but few can sustain it for long
since it is an energy draining exercise. Prolonged
hovering is mainly limited to specialists such as the kestrels of the Old and
New Worlds. But even these birds do
no more than fly steadily into a light wind as they lack the muscle power to
hover properly in still air.
Like
all falcons, American kestrels have evolved for speed in flight and can dive at
speeds of up to 65 m.p.h. To
achieve this speed, its wings are slender and pointed and it is amazingly light,
weighing only about 1/4 pound!
Although
man is the biggest threat to kestrels, they could fall prey to a larger hawk or
falcon and have even been killed by ravens on occasion.
The domestic cat also poses a threat to these small birds.
Crows and ravens are destructive to the eggs when left unprotected in the
nest.
In
some areas, they are loosing their natural nesting sites such as cavities in
trees, and may depend on nest boxes being placed in these areas.
FOLKLORE AND MYTHS
Falconry
became a serious sport in England in 1066.
You could tell the rank of an Englishmen by the falcon he carried on his
wrist. The Old World kestrel was
carried by priests.
"Birds
of the Pacific Northwest", by Ira N. Gabrielson and Stanley G. Jewett,
1970, Dover Publications, Inc., New York.
"Birds
of Prey", by Philip Burton, 1989, Gallery Books, New York.
"Birds
of Prey of the World", by Mary Louise Grossman and John Hamlet, 1964,
Bonanza Books, New York.
"Peterson's
Guide to Western Birds", by Roger Tory Peterson, 1990, Houghton Mifflin
Company, Boston.