Scientific Name:
Accipiter gentilis
Nest Type: Platform
Nest Location: Coniferous
and deciduous trees; 18-75', avg. 20-60'
Clutch Size: 2-5;
avg. 3-4
Food: Birds and
small mammals
Foraging Guild:
Aerial pursuit and low patrol
The Northern Goshawk has
a holarctic distribution across North America, northern Europe, and
Asia (Palmer 1988). In Minnesota, it is primarily found in the northern
forested regions of the state, and is a relatively rare and secretive
species (Roberts 1932, Janssen 1987).
Throughout the range of
the Northern Goshawk, population and status estimates are difficult
to obtain and are often extrapolated from migration counts and banding
returns (Rosenfield et al. 1991). The species is considered a regular
nesting bird in northern Minnesota (Johnson 1982). Because of its secretive
nature, information on the species is noticeably lacking. The seasonal
high for migrating Northern Goshawks during fall observation at Hawk
Ridge Nature Reserve in Duluth was 5,819 in 1982.
The Northern Goshawk relies
on a prey base which utilizes both mammalian and avian species. Eng
and Gullion (1962) estimated that over 50% of Ruffed Grouse (Bonasa
umbellus) overwintering mortalities were the result of Goshawk
predation. However, Meng (1959) determined food habits at 14 Goshawk
nests in New York and Pennsylvania. Of 72 mammalian prey items identified,
58% were Red Squirrel (Tamiasciurus hudsonicus), and of
113 avian prey items examined, 83% were Common Crow (Corvus brachyrhynchos).
Palmer (1988) summarizes the diet as mainly game birds, hares, rabbits,
and squirrels. It has been known to consume birds as large as mallards
and as small as wood warblers. The diversity of diet and lack of exposure
in many forested habitats, particularly the selection of mammalian prey
items, may explain why Northern Goshawk populations in the upper Midwest
were presumably not affected as much as other raptors by organochlorine
contamination of food sources (Jones 1979).
Nesting habitats for the
Northern Goshawk are described as mature tracts of coniferous or mixed
forests (Bent 1937, Johnson 1982, Kingsley and Nicholls 1991). Although
the species has been found using a variety of forested and semi-open
habitats (Palmer 1988), in Minnesota its range lies primarily within
the heavily forested regions of the state. More detailed information
from Michigan (Brewer et al. 1991) suggests that the species uses both
deciduous, coniferous, and mixed deciduous-coniferous forests. Since
the species tends to nest in older deciduous trees (Palmer 1988), mixed
forests may indeed be favored. Brewer et al. (1991) further explain
that the species inhabits large stands of boreal and northern hardwoods
with a relatively open understory, which is important for hunting below
the canopy. Based on these data, this forest raptor was defined as dependent
on mature forests, but not associated primarily with coniferous forests.
Northern Goshawks mate
for life and utilize the same nesting areas each year (Jones 1979).
The use of traditional nesting sites by Goshawks in Minnesota is supported
by Gullion (1981) and Palmer (1988). The use of traditional nesting
sites in mature tracts of forests suggests that habitat may be an important
component for the Northern Goshawks in Minnesota. In Michigan, Brewer
et al. (1991) states that the most significant threat to the species
is habitat alteration through timber harvesting. They suggest that forest
harvesting will primarily affect the availability of suitable nest sites,
enhance the distribution of competitors (primarily Red-tailed Hawk and
Great Horned Owl), and affect the abundance of prey. They further suggest
that clear-cutting has led to the abandonment of formerly occupied sites
in Michigan. In Minnesota, little information exists on the potential
effects of forest practices on Northern Goshawk distribution and abundance.