Introduction:

On the forest floor, tall Douglas fir trees around you stretch their arms to the sky. Sunlight dances through the canopy onto the forest floor, illuminating the green leaves surrounding your home. Life down on the ground ain’t so bad. Heck, life as a rabbit ain’t so bad. While birds sing in the tree tops, a fresh breeze swirls across your back. Nature’s silence. A few moments later you hear a crash. As you turn to see what’s caused the commotion you’re faced with this. Eyes locked onto you like a missile, silent wing beats allowed this predator to show up right behind you. It may be half your size but it’s faster than you. You try to turn and run. Within a moment you’ve been ambushed and trapped beneath the claws of a Northern Goshawk without a hope of escaping. These are the tales of the forest ghost’s victims.

Description:

The Northern Goshawk (Accipiter gentilis) is a stout, stealthy hunter and a powerful predator (Aubudon, 2020). It’s species name comes from the latin word gentilis meaning “of or belonging to the same family” (Wordsense.eu). They are the largest of the group, you guessed it, the accipiter hawks, also known as the true hawks. Related to their locally known smaller cousins the cooper’s and sharp-shinned hawks, the Goshawks are much more inconspicuous. They are the largest in the family Accipitridae. Out of the 50 species in the family, the sizes range from the thrush sized sparrowhawk of Africa, up to a Goshawk, which is the same size as a red-tailed hawk (Britannica, 2019). The species is reverse dimorphic meaning the females are larger than the males. Ranging from 53-64 cm tall, 0.6-1.4 kg heavy and a wingspan up to 117 cm (All about birds). They are agile hunters using the element of surprise and speed to their advantage.

Identification:

Adult Northern Goshawks have a dark grey back with light grey and white barred underparts (Fig 2). Above their menacing orange to red eyes lies a white stripe (Sibley, 2016). Juveniles are more likely to be confused with other smaller accipiter hawks, like the eurasian sparrowhawk (which only occur in Europe and Asia) and the cooper’s hawk, but the larger and broader-winged Goshawk makes a bold statement with their white eyebrows and streaking on the underparts (Fig 3)(ebird). There are 9 subspecies throughout the world, each varying slightly in head colour and amount of white and barring on underparts (Ferguson-Lees et al. 2001). Accipiter gentilis laingi is the subspecies that occurs in B.C. with lighter barring on their chest compared to the European and Asian populations and a more rufus overall hue (All about birds). Northern Goshawks are relatively quiet, they have an alarm call and make a “kak-kak-kak-kak” sound when disturbed or chasing prey (Audio below) (Aubudon, 2020). They are fiercely protective of their nest and will let you or other animals know when they’ve gotten too close (All about birds).

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Distribution and Habitat:

These majestic birds are found in the northern hemisphere throughout North America, Europe and Asia (Ferguson-Lees et al. 2001). In North America, they range as far south as the inland tropics of Mexico, as far north as the chilly western tip of Alaska and in every single province in Canada (Fig 4) (All about birds). Dense forest habitats are where these predators shine. Preferring mature coniferous or mixed forests, away from suburban areas (ebird). Notice the longer tail common in forest hawks, which is used to help brake and maneuver quickly at high speeds (Fig 3). The Northern Goshawks seek large trees within an area to nest. The nest is built near the trunk on a horizontal branch (All about birds). Females build the nest first out of sticks and then line the interior with softer bark and greenery (All about birds).

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Behaviour:

They are a sprinter. They locate prey by watching from a perch above before navigating through the thick vegetation for their kill (Audubon, 2020). Goshawks are watchful predators, awaiting for prey to become visible in the forest canopy or ground below. They fly between elevated perches for an aerial view of potential meals below, striking swiftly with speed when an opportunity arises. They sometimes will stalk prey on foot or flying low with a watchful eye along the forest edges. They have a wide palate for birds, mammals, reptiles, insects and will sometimes scavenge pre-existing kills (Audubon, 2020). Grouse, woodpeckers, corvids, squirrels and rabbits are typical meals for these well versed birds. During courtship, Goshawks perform a sky dance which involves high circling and slow flapping, ending in a dive towards the tree tops (Hawk Mountain). Aerial displays include tucking in the tail feathers accompanied by the spreading and retracting of under-coverts called ‘tail flagging’ (Ferguson-Lees et al. 2001). Breeding pairs may mate for life and sometimes use the same nest between years, however it is more common for the female to make a new nest (Audubon, 2020). These birds are fairly sedentary, if they are going to disperse it happens in the summer months, especially for those living in higher altitudes (Ferguson-Lees et al. 2001). Typically the northern populations are more migratory and the southern populations more sedentary (Hawk Mountain).

Conservation Status:

In 2013, COSEWIC re-examined and confirmed the listing in 2000 of the Northern Goshawk subspecies A. g. laingi as a threatened population (COSEWIC, 2013). Genetic studies further discussed below have proven the A. g. laingi subspecies to be much more genetically distinct compared to the rest of the Northern Goshawks found in North America (Fig 5)(Geraldes et al. 2019). Over half of the habitat and range for this subspecies is in British Columbia with our mature coniferous forests which are in decline due to forestry and shorter harvest times. The Haida Gwaii population is at risk from introduced deer populations that are over-grazing the forest understory resulting in a decline of prey species (COSEWIC, 2013). Approximately 35-36% of nesting and foraging habitat for the Northern Goshawks are protected in Canada (COSEWIC, 2013).

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Interesting Tidbits:

• Goshawks have been used extensively in falconry. They were, in a lot of cases, the first birds to be used in falconry for multiple countries (Woodruff, 2020). Goshawks are extremely consistent and reliable hunters which makes them widely used for capturing food (Woodruff, 2020). A study conducted in Britain from 1970-1978 tracked the fate of 216 Goshawks imported from Finland for falconry use. They contacted owners biennially to track the fate of these animals and causes of death finding a death rate of 22% per year (Kenward et al. 1981). They are difficult animals to care for because of their fragility and not recommended as a first bird for new falconers (Woodruff, 2020).
• The Northern Goshawk was on the helmet of Attila the Hun as it represents a symbol of strength (Hawk Mountain).
• Personal hygiene is of utmost importance as they need to bathe on the daily (Woodruff, 2020).
• It used to be referred to as “the cook’s hawk” because of it feeds on grouse, ducks, rabbits, and hares (Hawk Mountain).
• About half of all Siberian Goshawks are nearly all white to blend in with the snowy terrain (Fig 6 & 7) (All about birds).

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Areas of Research:

Much of the research about Northern Goshawks is about determining the subspecies ranges and differentiating between the populations around the globe. Lots of genetic work helps scientists determine the needs of each population for better management and conservation efforts.

There has been a spotlight on the Haida Gwaii Accipiter gentilis laingi subspecies, even making the CBC news. The population has been isolated on the Queen Charlotte islands for 20,000 years as they do not make migrations over large bodies of water (Alam 2019). The study conducted by Geraldes et al. last year (2019) took samples from 433 Northern Goshawks, as well as european subspecies A. g. gentilis, cooper’s hawk, sharp-shinned hawk, red-tailed hawk and a bald eagle to compare various gene loci. They used tissue samples from museum specimens, fallen feathers beneath nests, and blood samples from live specimens. The Haida Gwaii population was proven to be very distinct between the rest of North American and even other British Columbian Goshawks. This indicates the need for more specific conservation efforts towards the isolated population (Geraldes et al. 2019). Similar studies in Japan have compared their Honshu and Hokkaido populations of Northern Goshawks, which are also classified as vulnerable species, to determine the genetic diversity and status of these raptors. At the time of the study there was no concern yet in regard to a large genetic distinction requiring special conservation between the two. There is concern around imported Goshawks genetically polluting the native populations keeping them on biologists’ watch list (Takaki et al. 2009).

In the United States, studies on the home ranges of these birds was conducted by Moser & Garton in 2019. They radio-tagged 17 Goshawks from 17 different breeding locations in northern Idaho to compare their breeding ranges. Males had a mean range of 5,146 ha, 33% larger than the range of females at 3,859 ha (Moser & Garton, 2019). They concluded a larger breeding range in the north compared to Goshawks in the southwestern states. Males in Arizona had an average home range of 1,758 ha (Bright‐Smith & Mannan 1994). There are two other studies that confirm smaller home ranges in the southern states.

One last mentionable paper is on the genetic confirmation of a Northern Goshawk and cooper’s hawk hybrid. This was a wild hybrid between the two accipiter species caught at Cape May, off of New Jersey (Haughey et al. 2019). This is the first documented wild hybrid between the two accipiter species. There have been successful captive bred hybrids in the past which are often used in falconry deeming it possible but never any evidence of this happening outside of human control (Haughey et al. 2019). Hybridization between species can increase genetic diversity, be precursors to new species or traits (Grant & Grant 1992). Being the first example it may be difficult to tell what this means for either population, but nonetheless an interesting find!

Literature Cited:

Alam, H. (2019) Haida Gwaii home to a distinct but vulnerable pocket of northern goshawks. The Canadian Press. (Accessed November 12, 2020) https://www.cbc.ca/news/canada/british-columbia/haida-gwaii-home-to-a-distinct-but-vulnerable-pocket-of-northern-goshawks-1.4986017

Audubon Field Guide. (2020) Guide to North American Birds: Northern Goshawk. Retrieved November 10, 2020, from: https://www.audubon.org/field-guide/bird/northern-goshawk

Bright‐Smith, D. J, and R. W. Mannan (1994) Habitat use by breeding male northern goshawks in northern Arizona. Studies in Avian Biology 16:58–65.

COSEWIC Assessment and Status Report on the Northern Goshawk Accipiter gentilis laingi in Canada (2013) Environment Canada (Accessed November 9, 2020) https://www.sararegistry.gc.ca/virtual_sara/files/cosewic/sr_autour_palombes_northern_goshawk_1213_e.pdf

eBird (n.d.) The Cornell Lab of Ornithology. (Accessed November 9, 2020) https://ebird.org/species/norgos

Ferguson-Lees, J., Christie, D. A., Franklin, K., Mead, D., Burton, P. J. K., & ProQuest (Firm). (2001). Raptors of the world. London: Christopher Helm.

Geraldes, A, Askelson, KK, Nikelski, E, et al. Population genomic analyses reveal a highly differentiated and endangered genetic cluster of northern goshawks (Accipiter gentilis laingi) in Haida Gwaii. Evol Appl. 2019; 12: 757– 772. https://doi.org/10.1111/eva.12754

Grant, P., & Grant, B. (1992). Hybridization of Bird Species. Science,256(5054), 193-197. Retrieved November 13, 2020, from http://www.jstor.org/stable/2876983

Haughey, C. L., Nelson, A., Napier, P., Rosenfield, R. N., Sonsthagen, S. A., & Talbot, S. L. (2019). Genetic confirmation of a natural hybrid between a northern goshawk (accipiter gentilis) and a cooper’s hawk (A. cooperii): A journal of ornithology. The Wilson Journal of Ornithology, 131(4), 838-844. Retrieved from https://search-proquest-com.ezproxy.viu.ca/docview/2350469050?accountid=12246

Hawk Mountain (n.d.) Northern Goshawks are revered in many cultures as a symbol of strength. (Accessed: November 9, 2020) https://www.hawkmountain.org/raptors/northern-goshawk

Kenward, R., Marquiss, M., & Newton, I. (1981). What Happens to Goshawks Trained for Falconry. The Journal of Wildlife Management,45(3), 802-806. doi:10.2307/3808727

Moser, B.W. and Garton, E.O. (2019), Northern goshawk space use and resource selection. Jour. Wild. Mgmt., 83: 705-713. https://doi-org.ezproxy.viu.ca/10.1002/jwmg.21624

Sibley, D.A. 2016. Sibley Birds West: Field Guide to Birds of Western North America. Alfred A. Knopf, New York, New York. pg 99.

Takaki, Y., Kawahara, T., Kitamura, H. et al. Genetic diversity and genetic structure of Northern Goshawk (Accipiter gentilis) populations in eastern Japan and Central Asia. Conserv Genet 10, 269–279 (2009). https://doi-org.ezproxy.viu.ca/10.1007/s10592-008-9567-4

The Cornell Lab of Ornithology. (n.d.) All About Birds: Northern Goshawk. Retrieved November 9, 2020, from: https://www.allaboutbirds.org/guide/Northern_Goshawk/overview

The Editors of Encyclopaedia Britannica. June 14, 2019. Accipiter. Encyclopaedia Britannica (November 10, 2020) https://www.britannica.com/animal/accipiter

Woodruff, B. (Director). (2020, March 15). Falconry: Introduction to goshawks [Video file]. Retrieved November 12, 2020, from https://www.youtube.com/watch?v=v5SOwgirewc

Word sense.eu (n.d.) “gentilis” in WordSense.eu Online Dictionary (Accessed: November 10, 2020) https://www.wordsense.eu/gentilis/