Monday, May 20, 2013

The Northern Hawk Owl

The Northern Hawk Owl is adept at capturing rodents
under the snow due to their great hearing.

The Northern Hawk Owl is a non-migratory owl that resembles a hawk in behavior and appearance. During flight it looks similar to a Cooper's Hawk. It is one of the few owls that is primarily active during the day.
   Northern Hawk Owls are unevenly distributed throughout the boreal forest. They live mostly in open coniferous forests, or coniferous/deciduous mixed forests of Canada and Alaska, sometimes extending down to other northern states during winter or after a population explosion in their prey. They are also found across northern Eurasia, reaching Siberia at its eastern range. 
   Their prey includes small rodents (usually voles) snowshoe hares, red squirrels, and a variety of birds. During winter, they prefer to feed on ground-dwelling birds such as grouse and ptarmigans. The Northern Hawk Owl's fortune rises and falls with its prey. During prey population explosions, their numbers can swell to more than 50,000 breeding pairs, but if food is scarce, their numbers dwindle accordingly.
   The hunting strategy for the Northern Hawk Owl is to perch on a spruce tree in open forest and scan the immediate area for prey. If nothing is found, they move on to another location. When prey is spotted, the owl attacks by going from a horizontal position into a gliding dive. If the prey is further away, the bird will flap its wings a few times during the dive to make up the extra distance. This owl has superb hearing and can plunge into snow to capture rodents beneath the surface.
   The Northern Hawk Owl is one of the least studied birds in North America. They are hard to study because of a low, fluctuating population density and remote breeding locations. This lack of knowledge makes it nearly impossible to accurately estimate the population levels of this species.
   Northern Hawk Owl densities are estimated to be at most six pairs per 100 sq km. But because they live throughout the boreal forest, the North American population is thought to be quite large. In North America, over half of their breeding territory occurs in non-commercial boreal forests, so as long as nothing threatens this habitat, the species should be OK even though the populations seems to be declining. Improved monitoring should be a high priority so that we can be more confident in that assessment.

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