Thứ Ba, 18 tháng 10, 2011

Sharp-shinned Hawk and Coopers Hawk



coopers hawk photoThe sharp-shinned hawk and Coopers hawk are a common and exciting part of the ecology of many suburban parks, woodlands, and neighborhoods. These two members of the family known as Accipitridae, are built for speed and maneuverability. Like all members of their family, they are characterized by their short wings and long tail. Both hawks live mainly on a diet of birds. Though the two types of hawks are often confused, there are some definite differences.Telling them apart
These two hawks can be confusingly similar in physical appearance, so here are some ways to tell them apart:
Sharp-shinned hawk (Accipiter striatus)
  • This hawk is the smaller of the two, generally around the size of a jay.
  • Body length: Male= 10-12”, Female=12-14”
  • Wingspan: Male= 20-24”, Female= 24-28”
  • In typical flight, tail appears squared off and not rounded. Head appears small. Close-up, the eyes look very round and kind of “bug-eyed.”

Coopers hawk (Accipiter cooperii)
  • This hawk is larger, generally closer to an American crow in size.
  • Body length: Male= 15-17”, Female= 17-19”
  • Wingspan: Male= 27-32”, Female= 32-37”
  • In typical flight, tail appears rounded off at the end. Head appears large. Close-up, the eyes look stern and have a thin, yellowish ridge sticking out slightly over them.

sharp-shinned hawk photo Natural History As you may have noticed from the measurements above: the female Coopers hawk and sharp-shinned hawk are larger than the males. This is true for most birds of prey throughout the world. Some ornithologists believe that this size difference is an adaptation which minimizes competition between the sexes, allowing the female birds to hunt prey that is too large to tackle for the male hawks.
Sharp-shinned hawks hunt mainly small to medium sized songbirds. Meanwhile, Coopers hawks hunt medium songbirds and birds up to the size of grouse or small ducks. Coopers hawks also hunt some small mammal prey such as rats, chipmunks and squirrels.
Both hawks are very fast in level flight, and often catch birds in mid-flight with a swift grab from their sharp talons. Incredibly, these hawks can fly at nearly full speed through dense woodlands and squeeze through gaps not much larger than their body width without even breaking stride!
Both of these species help keep birds populations healthy by taking out those who are unhealthy or unwary. Although some bird watchers express great frustration at observing these birds of prey hunting the songbirds that visit their feeders, it is important to remember that they help keep the feeder a healthier place for the birds to eat. Over-crowding at bird feeders and feeding stations can cause a variety of problems, including helping spread disease between and among species of songbirds.
If you are lucky enough to witness these hawks flying around in your area, enjoy watching some of the best aerial hunters in the world!
soaring hawk photo

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