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Northern Goshawk

Accipiter gentilis

by Damian Fagan

I count my strides as I proceed through the Ponderosa woodland, "seventy-eight, seventy-nine". I stop to recheck my compass bearing. Hundred and twenty, hundred twenty-one… I close on my final destination, Point #226. As I reach hundred thirty-eight, I drop my pack and pull out my small CD player with attached speakers. I look around for a couple of minutes, then hit PLAY. The silence is interrupted by the loud repetitive keck, keck, keck, keck recording of an adult Northern Goshawk alarm call. After a short interval, the tape goes silent. I’ve played this recording so many times that I feel the call looping through my brain.

Adult Northern Goshawk

With each section of silence, I turn to face a new direction. I sort out the replies of the usual suspects – Red breasted Nuthatch, Steller’s Jay, and Mountain Chickadee, which respond to this tape with their scolding calls. They expect something other than me because they know the sounds of an intruder when they hear one. The nuthatches and chickadees are small enough to probably avoid becoming prey, as they seek to send this threat out of their turf. Not so the jays, as demonstrated by the occasional piles of dark blue feathers I encounter along my survey transect.

Again, another series of recorded calls and silence. As I listen for a response, I scan the woods in case a Goshawk arrives unannounced. Visibility is pretty good at this location. There are few low limbs or understory plants to block my view. Silence. Rotate. Call. Silence. Nothing.

At the end of my session, I jot down a few notes on my data sheet, place a big N in the response column, and reshoulder my pack. Since I’m following the same bearing to the next point, I recheck the compass and continue on. One, two, three.

Just another day at work on a Northern Goshawk inventory project.

As a contract biologist, I’ve worked on Northern Goshawk surveys in Utah, Arizona and California. Though the terrain and habitat has varied, the protocol remains the same. I follow a pre-set transect line, with calling stations placed about every 200 meters. At each point, I use a tape playback method that utilizes recorded calls of adults or juvenile Goshawks to elicit responses from those in the neighborhood. I continue, on foot, using a compass and intermittent flagging to find my next calling station.

Using these calls and visual clues (plucked birds or small mammals or lots of bird excrement below a tree) a surveyor can search for territorial occupancy across a large section of forest. Once a response is recorded, then a nest search can be initiated. When you encounter an aggressive bird making repeated attempts to take off your head, all the while cackling like crazy, then you know you are getting close to a nest.

Later on in the season, I’ll switch the broadcasts along these same transect lines to the juvenile food begging call. This calling period coincides with the age of the young nestlings.

Though the work is demanding, often exhausting and fraught with “face” plants (unseen roots or deadfall that trip you) and branches slapping you in the face (abundant understory), it is very rewarding. You get plenty of exercise and fresh air, see some interesting wildlife, occasionally find signs of past (or present) illegal activities, and avoid the “real job” that your parents or spouse might want you to undertake.

Name

The scientific name of the Northern Goshawk is Accipiter gentilis. Accipiter means “hawk or bird of prey” and gentilis means “belonging to the same (noble) clan”. Goshawk is a combination of Old English words meaning “goose hawk”.

Range

The breeding range of the Northern Goshawk extends from western Alaska to Newfoundland, south into New England, the upper Midwest and the Pacific Northwest, as well as throughout parts of the Southwest, the eastern foothills of the Rockies, and along the central mountains in Mexico. Northern Goshawks also occur in Eurasia.

The birds may winter throughout much of their North America breeding territories, except for portions of western California and the Gulf Coast states. Goshawks are neither long distance migrants nor do they migrate in mass, like Swainson’s Hawks, to warmer climates in South America. However, there are sporadic invasions of birds from the northern portions of the range, like the arctic and boreal forests, southward during years of low prey base in their northern territories. These invasions or irruption’s follow crashes of Northern Grouse or Snowshoe Hare populations, on average, about every 10 years.

Immature Northern Goshawk

Size

Northern Goshawks exhibit a sexual dimorphism, meaning there are “two forms” to the sexes: females are larger than males. These birds are large (21 to 25 inches on average) and have broad, buteo-like wings that are 41 to 46 inches wide. The trailing edge of the wing forms a distinctive S-shape and is narrow at the tip. Adults weigh between 22 to 48 ounces, here again the males are lighter than the females.

Overall, Goshawks may be confused for one of the smaller soaring hawks or buteos like the Red-shouldered Hawk.

In Arthur Bent’s Life Histories of North American Birds of Prey, Herbert Ravenel Sass is quoted as saying:

“None will dispute the Goshawk’s title to a place among the Kings of Winter. A big hawk, longer but less bulky that the red-tail…with brilliant orange eyes through which the fierce spirit of the fiery hearted warrior gleams at times like points of living flame – the Goshawk ranks second to none in terms of martial beauty and in fearlessness.”

Color

The plumage of adult Goshawks is very different than that of the juveniles. Adults have a grayish underside marked with fine black feathers – the markings resemble calligraphy characters. A white eyebrow line separates their dark caps from the black eye stripe. The back is a pale blue-gray color, browner in adult females, while the tail shows several alternating light and dark bands. Iris color changes from pale greenish-gray in juveniles to an orange-red or dark red in adults.


Juveniles are similar to those of other members of the Accipiter Family – the Sharp-shinned and Cooper’s Hawks. Although larger in size than their relatives, the juvenile Goshawks have large, teardrop sized brownish marks on their undersides. This streaking makes the bird appear dirty at a distance. Closer up this streaking has a checkerboard appearance. Their backs are a mottled brown.

Hunting

Goshawks are mainly perch-and-pounce predators. They wait quietly for prey to appear, then chase them down with an impressive single-mindedness. They have been known to pursuit prey through thickets and tangled understories in woodlands, if need be. Though large in size, their rounded wings and long tail enable them to navigate through tight spaces.

Their other hunting technique is to use a low level, but fast-concealed flight through forest edges or clearings. Surprised prey may seek to outrun or dive into cover, although the Goshawk may give chase through thickets and brambles.

In Bent’s Life Histories of North American Birds of Prey, Lucient Turner in 1886 describes the hunting prowess of a Goshawk in Alaska:

“I have seen this hawk sail without a quiver of its pinions, until within seizing distance of its quarry, and suddenly throw its wings back, when with a clash they [a Ptarmigan] came together, and the vicinity was filled with white feathers, floating peacefully through the air.”

Prey species are location dependent, and consist mainly of small mammals and birds such as Snowshoe Hares, cottontails, ground squirrels, chipmunks, grouse, jays, woodpeckers, smaller hawks, and robins.

Goshawks look for prey such as this chipmunk.

Nest Site

Goshawks construct large stick nest in trees such as Ponderosa Pine, Lodgepole Pine, Douglas Fir, Quaking Aspen, Subalpine Fir or cottonwood. The nest tree depends on the location and habitat where the bird occurs. The nest is often built in a crotch where the tree trunk splits or up against the trunk. They often occur in mature coniferous or hardwood forests that are punctuated with openings or clearings.

Adults, the females especially, are very territorial around their nest site. I have been screamed at and dive-bombed while over 200 yards away from a nest site, causing me to retreat from the area. Sometimes the adults sit tight and do not utter a sound, waiting and watching intruders pass through their territory.

Mating displays include slow flapping of the wings near a mate, varied flight displays that include dips and dives, and fluffed undertail feathers that resemble pantaloons in flight.

On average, two to four eggs are laid per nest. The adults switch off during the incubation period, which is around four to five weeks long. The nestlings grow quickly and the size difference between the sexes can be very noticeable. The young will leave the nest at around 35 to 36 days old, and remain in a “post-fledging territory” near the nest site while the adults instruct the young on the finer points of snagging prey.

Longevity

A wild-banded bird lived to be 13 years old in Minnesota.

Falconry

Northern Goshawks are still used in falconry today, but during the Middle Ages, there was a hierarchy established for the type of bird a person could posses for falconry. For the Emperor, it was a Golden Eagle or a Gyrfalcon. A lowly yeoman or landed gentry could have “only” a Goshawk.

Attila the Hun wore an image of a Northern Goshawk on his helmet, which may give you some idea of the bird’s attitude.

Migration Stations

In the Southwest, Hawkwatch International monitors certain raptor flyways where Northern Goshawks may be observed. These sites are in Utah’s Wellsville Mountains, Nevada’s Goshute Mountains, and New Mexico’s Sandia and Manzano Mountains. September is an excellent time to visit these locations.


g
Animals, How They Are Classified
Cooper's Hawk
Ferruginous hawk
Marsh Hawk
Northern Harriers
Sharp-shinned
Red-Tailed Hawk


 


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