INDEX:
WHAT
IS A MARSH HAWK?
WHAT
IS ITS ROLE IN THE GREAT SALT LAKE MARSHES?
WHERE
DO THEY LIVE?
HOW
DO YOU IDENTIFY THE MARSH HAWK?
MATING
AND NESTING
HOW
DO I FIND OUT MORE ABOUT OTHER GREAT SALT LAKE RAPTORS?
The Northern harrier, more commonly called the marsh hawk, belongs to the family
Accipitridae, along with kites, accipiters, and eagles. The genus and species of the harrier is
Circus cyaneus. (See
above image)
WHAT IS ITS ROLE IN THE GREAT SALT LAKE MARSHES?
Harriers of the Great Salt Lake ecosystem receive energy and nutrients necessary for their
survival by feeding on certain organisms around the Great Salt Lake. One of the most important
food sources for the harrier is the meadow vole, which lives in the grasslands around the lake, and
is there year-round.
See meadow
vole.
Small
birds are also an important food source for the harrier. The marsh
hawk often feeds on
migratory birds of the Great Salt Lake. One of the more common of these migratory birds is the
Wilson's Phalarope, which arrives in Utah around mid-June, and leaves late July and into August;
thus, providing food for the harrier for these few summer months. Another common migratory bird
that provides food for the harrier is the Eared Grebe, which arrives to the Great Salt Lake around
the end of June, and leaves during the winter months.
Other birds eaten by the harrier include waterfowl, such as Cinnamon and Green winged Teal,
and Avocets. Refer back
to Great Salt Lake food web in the
introduction.
Marsh hawks are found in marshes, meadows, and fields. They are common residents of
Utah, and many remain year-round; although, migration takes place in the northern part of the
range in North America. Northern harriers breed from Alaska through Canada and the northern
half of the United States; and winter from the middle United States into Mexico. Those that
migrate leave Utah during November, and arrive again in March or April. During spring and
summer, harriers eat approximately 12% of their body weight per day. During the colder seasons,
they eat approximately 19% of their body weight per day. Hunting for these birds consists mainly
of small rodents and birds, over two thirds of their diet. Insects, snakes, and frogs are also
occasionally eaten. Harriers
sometimes feed on carrion, although they prefer live prey.
HOW DO YOU IDENTIFY THE MARSH HAWK?
It is a slim hawk with long wings, tail, and legs, and also a small head. It is generally 17 1/2 to
24 inches in length, with a wingspan of 42 to 54 inches. Distinctive features of the marsh hawk
include: a white rump patch; an owl like face; and the low quartering flight over fields and marshes,
with the wings held in a shallow "V" position.
white under parts, and some reddish spotting. They also have black wing tips. Adult females are
brown with some brownish streaks on the under parts. They are also larger than the males. The
males weigh approximately 472 grams(1.04 lbs.),while the females weigh approximately 570
grams(1.25 lbs.). Juveniles closely resemble the female but are cinnamon on the under parts;
however, this color fades by mid-winter.
The nest of the marsh hawk consists of sticks and grasses, on the ground or on low
vegetation. Both birds participate in nest construction, but brooding is done by the female. Mating
takes place in Utah around early April, and nesting begins by early May. The distinctive courtship
flight of the male during March and April is said to be spectacular. The flight consists of dives from
50 to 100 feet, swooping near the ground and climbing again to repeat the process. The apex of
the climb is usually terminated by a roll or somersault before the next dive. See northern harrier.
Three to nine eggs are laid in the nest, on average five. The eggs are white, sometimes splotched
with brown. The incubation period is 31 days. Before the young can fly, they leave the nest and
scatter throughout the surrounding
vegetation. Age at first flight is 30 to 35
days.
HOW
DO I FIND OUT MORE ABOUT OTHER GREAT SALT LAKE RAPTORS?
To find more information on other Great Salt Lake raptors, (which include the Bald and Golden
Eagle, the Peregrine Falcon, the American Kestrel, and the Red-tail Hawk), as well as other birds,
visit these sites:
http://www.raptor.cvm.umn.edu/newwebdev/raptor/rfacts/rfacts.html
; http://www.hawkwatch.org/
; http://www.suttoncenter.org/other.html
.
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REFERENCES
Peterson, Roger Tory; A Field Guide to Western Birds; Riverside Press, 1961.
URL: Gothard, Greg; (http://home.sprynet.com/sprynet/chip_tg/harr.htm).
URL: Wetnet-Northern Harrier; (http://www.glo.state.tx.us/res_mgmt/wetnet/species/harrier.html).
URL: Conover, Kirsten; Simon-Brown, Viviane; The High Desert Museum; (http://www.highdesert.org/birds6.htm).
URL: Grassland Animals-Meadow Vole; (http://www.mobot.org/pfg/diverse/biomes/grasslnd/animals/vole.htm).
URL: The Raptor Center
at the University of Minnesota; Raptor Facts-Northern Harrier; (http://www.raptor.cvm.umn.edu/newwebdev/raptor/rfacts/nharr.html).