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Goshawk Monitoring

The Northern Goshawk (Accipiter gentilis) is a secretive forest raptor occupying boreal and temperate forest across the holarctic. The goshawk is considered a sensitive species by the USDA Forest Service and has been petitioned on two occasions for endangered species status. Many national forests utilize the goshawk as a management indicator species. As a result, our Forest Service partners are very interested in the ecology, population structure, and trends of this species within their management domain.

The Intermountain Bird Observatory has studied
the Northern Goshawk off and on for 20 years

We have contributed directly and consulted for a number of forest management plans in Idaho and elsewhere, and have published a number of peer-reviewed scientific journal manuscripts (listed below; a few more are in the works!).



Objectives


Advancing the core science for the species,
focusing on the breeding and post-breeding ecology

  • Adult female Northern Goshawk on territory, South Hills, Idaho

    Adult female Northern Goshawk on territory, South Hills, Idaho

  • Adult female incubating eggs on a nest in an Aspen tree, South Hills

    Adult female incubating eggs on a nest in an Aspen tree, South Hills

  • Whole Beldings Ground Squirrel and unidentified avian prey remains emphasize the unusual diet of goshawks within the area, South Hills, Idaho

    Beldings Ground Squirrel and avian prey remains emphasize the unusual diet of goshawks in the South Hills


Evaluating the population trends for the species

Dead nestling on ground below a nest. Likely predation by avian predator (Great Horned Owl?), South Hills, Idaho

Dead nestling on ground below a nest. Likely predation by avian predator (Great Horned Owl?), South Hills, Idaho

Color Band on Goshawk Leg

Purple color band Z3. Color bands are used to identify and track individuals from year to year, without requiring them to be re-trapped. This individual was banded in the South Hills in 2012 and was found breeding in the Albion Mountains in 2014 and 2015


Evaluating the response of the species to changes occurring within the forest

(e.g., increased anthropogenic disturbance, climate change, disease outbreaks, timber harvesting).

ATV trail directly beneath Northern Goshawk nest, Sublett Mountains, Idaho

ATV trail directly beneath Northern Goshawk nest, Sublett Mountains, Idaho

Adult male goshawk trapped in un-capped water tank (later rescued), Sublett Mountains, Idaho

Adult male goshawk trapped in un-capped water tank (later rescued), Sublett Mountains, Idaho

Fire, natural and human caused, poses a threat to historical nesting territories, Black Pine Mountains, Idaho

Fire, natural and human caused, poses a threat to historical nesting territories, Black Pine Mountains, Idaho


Evaluating the genetic health of this species within the forest
and across the western United States

Mitochondrial gene sequences of Northern Goshawks from the South Hills, Idaho

Mitochondrial gene sequences of Northern Goshawks from the South Hills, Idaho


Evaluating threats to this species, with an emphasis on blood parasites

Nestling goshawks covered in black flies, a known vector of the Leucocytozoon blood parasite, South Hills, Idaho

Nestling goshawks covered in black flies, a known vector of the Leucocytozoon blood parasite, South Hills, Idaho

Blood parasite (leucocytozoon; blob in center of photo) mixed with avian red blood cells, from a Northern Goshawk in the South Hills, Idaho

Blood parasite (leucocytozoon; blob in center of photo) mixed with avian red blood cells, from a Northern Goshawk in the South Hills, Idaho


Providing educational and training opportunities for students
preparing for a career in wildlife biology

Raptor biologist Rob (right) instructing student researcher Steph (left) on banding technique of this adult female goshawk, South Hills, Idaho

Raptor biologist Rob (right) instructing student researcher Steph (left) on banding technique of this adult female goshawk, South Hills, Idaho, 2014

Student researcher Kenny (left) and forest wildlife biologist Scott banding a goshawk nestling, Sublett Mountains, Idaho

Student researcher Kenny (left) and forest wildlife biologist Scott banding a goshawk nestling, Sublett Mountains, Idaho, 2015

Student researcher Michelle holding adult female goshawk for banding, South Hills, Idaho

Student researcher Michelle holding adult female goshawk for banding, South Hills, Idaho, 2014

High school student Austin holding nestling goshawk before it is placed back into the nest, South Hills, Idaho, 2014

High school student Austin holding nestling goshawk before it is placed back into the nest, South Hills, Idaho, 2014



Goshawk Journal Articles


Bechard, M. J., G. D. Fairhurst, and G. S. Kaltenecker. 2006. “Occupancy, Productivity, Turnover and Dispersal of Northern Goshawks in Portions of the Northeastern Great Basin.” Studies in Avian Biology 31: 100–108.

Key findings: Over a 10-year period in southern Idaho, Northern Goshawk productivity was lower and turnover was higher than in other areas where goshawks are studied.


Hasselblad, K., M. J. Bechard, and J. C. Bednarz. 2007. “Male Northern Goshawk Home Ranges in the Great Basin of South-Central Idaho.” Journal of Raptor Research 41: 150–155.

Key findings: Male home range (hunting area) within the South Hills is on average smaller than other places where goshawks are studied, suggesting abundant food availability during the core of the breeding season.


Miller, R. A., J. D. Carlisle, M. J. Bechard, and D. Santini. 2013. “Predicting Nesting Habitat of Northern Goshawks in Mixed Aspen-Lodgepole Pine Forests in a High-Elevation Shrub-Steppe Dominated Landscape.” Open Journal of Ecology 3: 109–115.

Key findings: Within the South Hills, Northern Goshawks tend to nest in gently-sloping, east-facing, non-rugged areas of dense aspen and lodgepole pine forests with low reflectance in green wavelengths. This makes up about 8% of the forest, enabling us to more easily discover new territories.


Miller, R. A., J. D. Carlisle, and M. J. Bechard. 2014. “Effects of Prey Abundance on Breeding Season Diet of Northern Goshawks (Accipiter Gentilis) within an Unusual Prey Landscape.” Journal of Raptor Research 48: 1–12.

Key findings: The South Hills and Albion Mountains lack the usual top prey species for goshawks, tree squirrels. We found that goshawks within the South Hills consume 18.5% birds and 78.7% mammals, dominated by the Belding’s Ground Squirrel (75% of biomass). Beldings Ground Squirrel are thus critical for breeding success, but have different availability due to hibernation and estivation (only above ground for 3 months). This presents unique challenges for the goshawk, an area we continue to study.


Jeffries, M. I., R. A. Miller, M. D. Laskowski, and J. D. Carlisle. 2015. High Prevalence of Leucocytozoon Parasites in Nestling Northern Goshawks (Accipiter gentilis) in the Northern Great Basin USA. Journal of Raptor Research 49: 294-302.

Key findings: 100% of the nestlings tested (28 individuals from 12 nests), were infected by Leucocytozoon blood parasites. The intensity of infection was slightly higher for goshawks nesting in Aspen versus those nesting in Lodgepole Pine. We believe these infections pose an additive threat to individuals under stress from other factors, but are not killing them outright.