BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Accipiter gentilis | Northern Goshawk 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Age at first reproduction:  Some yearling females breed with older
males; yearling males are typically incapable of breeding [16].
Generally, 25 percent of northern goshawks breed as yearlings, another
25 percent in their second year, and the remainder in their third year
[5].

Pair formation:  Northern goshawks are monogomous.  If a mate is lost
the northern goshawk will form another pair bond [16].

Nesting:  The northern goshawk selects a preexisting nest or builds a
platform nest [11].  Nesting occurs from early April to mid-June,
depending on latitude [16].

Clutch/incubation and fledging:  The clutch size of the northern goshawk
varies from one to five eggs, with a mean of three eggs per clutch.  One
egg is laid every 2 days.  If a nest is destroyed early in the breeding
season, the northern goshawk will nest again.  Incubation period is 32
to 34 days.  The young fledge in 37 to 41 days with the smaller,
faster-developing males fledging a few days before the females [16].

Migration:  Winter migration begins in late August to early September.
Spring migration begins in early Feburary and is usually complete by
mid-March.  Many birds, however, remain in their territories year-round,
only moving when prey is limited [16].

Molting:  The female northern goshawk begins molting at the start of
incubation, and pauses when the young are about ready to fledge.  The
male molts during this pause.  The female resumes molting when the young
are flying and hunting on their own [16].


PREFERRED HABITAT : 
The northern goshawk uses a wide variety of forest ages, structural
conditions, and successional stages [17,18].  For hunting habitat, the
northern goshawk prefers the transitional zones from bog to forest and
forest to shrubland.  Riparian zones and mosaics of forested and open
areas are also important hunting habitats [4,16].  The northern goshawk
uses stands of old-growth forest as nesting sites [4].


COVER REQUIREMENTS : 
The home range size for a pair of northern goshawks is about 6,000 acres
(2,400 ha).  Within the home range there are three areas of use:  the
nest area, the post-fledgling family area, and the foraging area.  Greater
than 20 percent of the home range is old-growth forest [17,18,20].

The nest area is about 30 acres (12 ha) in size, and it is usually
located on north aspects in drainages or canyons with streams [17,18].
The nest area is usually in a mature forest stand that has a
multilayered canopy with dense to open understory [12].  Within a home
range there are usually two to four alternative nest areas [17,18].  The
tree selected for nesting has a crotch, fork, or several limbs on one
side to support the platform nest [16].

The post-fledgling family area is about 420 acres (168 ha).  This area
is a mosaic of forest types that provide hiding cover for the fledglings
and habitat for abundant prey [17,18].

The foraging area is about 5,400 acres (2,160 ha).  This area consists
of a mosaic of shrublands, forests, and openings with perching trees to
observe prey [16,17,18].


FOOD HABITS : 
The northern goshawk selects two or three species of the prey species
available within its hunting territory.  It searches the area from the
forest floor to the lower canopy from a perch.  Once prey is observed
the northern goshawk will take flight and pursue its prey.  Once pursuit
is started and the cover becomes too thick for flight, the northern
goshawk will pursue prey on foot.  The diet of the northern goshawk
changes with the season.  In the spring and summer, it is mainly birds,
with a few small mammals.  In the winter, the diet consists of prey
species that do not migrate of hibernate.  In northern portions of their
range, northern goshawk prey upon ptarmigans (Lagopus spp.) in the
winter.  In southern portions of their range, they consume ruffed grouse
(Bonasa umbellus), blue grouse (Dendragapus obscurus), hares (Lepus
spp.), and red squirrel (Tamiasciurus hudsonicus) [16].

The wide distribution of the northern goshawk results in a varied prey
base.  Stomach and pellet contents show the following prey animals:
robin (Turdus migratorius), Stellar's jay (Cyanocitta stelleri), mallard
(Anas platyrhynchos), black duck (Anas rubripes), sparrows (Ploceidae),
warblers (Parulidae), kestrel (Falco tinnunculus), crows (Corvus spp.),
hares, cottontails (Sylvilagus spp.), chipmunks (Eutamias spp.), ground
squirrels (Spermophilus spp.), woodchuck (Marmota monax), muskrat
(Ondantra zibethicus), mice (Heteromyidae), and shrews (Soricidae spp.)
[16].


PREDATORS : 
The northern goshawk is fairly high in the food web; its predators are
large avians such as the bald eagle (Haliaeetus leucocephalus) and
golden eagle (Aquila chrysaetos) [3].




MANAGEMENT CONSIDERATIONS : 
Timber harvest can be part of a management plan to perpetuate northern
goshawk habitat providing the plan calls for retention of a minimum of
20 percent old growth in the northern goshhawk's home range.  Rotation
time for old-growth stands should be 150 years or more [17,18,20].
Reynolds and others [18] provided detailed information on the types of
management practices that enhance northern goshawk habitat.

During harvest, the snags within the harvest area should be retained.
When hunting, the northern goshawk usually observes its prey while
perched in a snag, and then pursues the prey animal.  Few pursuits are
started while already in flight [2,16,18].

When using spruce-fir forests as grazing areas, recommended utilization
of herbaceous cover is 20 percent.  Heavy grazing in these forests
reduces herbaceous ground cover, resulting in dense stands of trees.
This reduces the quality of the northern goshawk's habitat by reducing
populations of its prey species [18].

Forest management activities should not take place in nesting areas
during the nesting period [10,18].  Roads in the nesting area should be
kept at a minimum and should be closed during nesting.  Use of skid
trails is preferable to construction of permanent roads [18].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Accipiter gentilis | Northern Goshawk