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Archive for February 9th, 2011

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A down side to setting up a birdfeeder is that when you attract many little birds, you also attract predators. Recently, I came across these tell-tale markings in the snow, along with an array of fluffy feathers. I wasn’t sure who the victim might have been until I turned over a feather marked with blue…a Blue Jay. It appears that it was attacked from above by a hawk, who left the shadow of his (her) 22 inch wingspan in the snow. The Usual Suspects would be a Sharp-shinned Hawk (Accipiter striatus) or a Cooper’s Hawk (Accipiter cooperii).

Sharp-shinned and Cooper’s hawks are similar in appearance, with the former being a bit smaller in size. However, female hawks are larger than males, and a large female Sharp-shinned Hawk may be close in size to a male Cooper’s Hawk. The size difference between the sexes in Cooper’s Hawks is one of the greatest among hawk species. Sharp-shinned Hawks feed almost exclusively on small birds, while Cooper’s will also take small mammals, reptiles, amphibians and insects when they are available. Only 10 to 30% of all attacks on wild prey are likely to be successful, so hawks have little ‘down time’ after a successful attack before they must start hunting again. Sharp-shinned hawks prefer slightly smaller prey than Cooper’s, but both may target Mourning Doves, a species that often feeds on the ground in a flock. The hawks need about a Mourning Dove-sized meal per day to maintain energy levels.

Both Sharp-shinned and Cooper’s hawks breed in Southern Ontario. They are secretive woodland nesters and prefer dense forests. Both species suffered serious population declines associated with DDT and other pesticides, but numbers have improved since the 1970s. Although you can’t help feeling sorry for the victim, of course the hawks are just performing their role in the ecosystem, and it is exciting to catch a glimpse of one of these beauties, or even see the evidence of their presence written in the snow.

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