Thursday, June 28, 2007

Hawk families that hunt in organised squadrons

Birds of prey are not naturally cooperative, yet Harris's hawks, which are found in the deserts of Central and South America, hunt together in groups of from three to six birds. A breeding female may be joined by more than one male.

Assembling at dawn, they split up into scouting groups and make short forays in search of prey - usually jack rabbits - but gather together again from time to time. Sometimes the hawks capture an unwary rabbit by diving on it from different directions, but they also use a flush-and-ambush technique that is well suited to the rough and scrubby terrain with its abundance of cover. In this, some of the birds surround and watch the prey, ready to pounce, while others try to flush it from its hiding place.

Another method used is a relay attack in which each hawk of the team takes turns to chase and dive bomb the quarry - this demands the most energy so is the least commonly used. After the kill, the hunters divide the prey between them. A team of six birds is the most efficient in terms of energy expended, but even then each bird's average daily share is small - only just enough for its needs.

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