Hawking (birds)

Other birds, such as swifts, swallows, and nightjars, also take insects on the wing in continuous aerial feeding.

Some species, such as the olive-sided flycatcher of North America[2] and the ashy drongo of the Indian Subcontinent,[3] tend to choose an exposed perch, such as a dead tree branch overlooking a clearing, whereas others, such as the North American Acadian flycatcher[4] and the Asian small niltava[5] perch within the cover of foliage deep in a forest or woodland habitat.

A study of feeding behaviors in the family Tyrannidae categorized the following moves as ways of taking insect prey: aerial hawking (i.e. flycatching), perch-to-ground sallying, ground feeding (chasing after insects on the ground), perch-to-water sallying, sally-gleaning (can involve an hover-gleaning or a rapid strike), and gleaning while perched.

Bee-eaters catch bees in a similar manner and return to the perch to remove the sting before consuming.

When swallows fly higher to go after smaller insects, they adjust their fight style to glide more, like a swift.

The common nighthawk of North America flies in swift-like fashion on its long, slender, pointed wings.

[14][15] Hawking insects, like any feeding strategy, must provide a bird with sufficient nourishment to make the expenditure of energy worthwhile.

The strategies and tactics for feeding on airborne insects are inextricably related to the adaptations and lifestyles of the birds that employ them.

Although a sally from a perch may look like a single, rapid movement to the human eye, actually the bird must perform several moves: it begins its take-off by pushing with its feet to get into the air, it flaps its wings to generate forward motion (thrust), pursues the prey item, turns in the air, flies back, and, with a final flurry of wings, lands on its perch.

When a bird hawks insects, the prey must be substantial enough to pay off in terms of a biological energy budget.

Birds in more open settings that sally after larger insects like bees, such as kingbirds and bee-eaters, benefit from longer, more pointed wings,[4] which are more efficient because they generate more lift and less drag.

Another function of long, pointed wings is to enable these birds to turn quickly and smoothly in mid-glide.

[20] The preference for certain kinds of aerial insect as a food source seems to correlate with gregarious or colonial behavior versus territoriality.

For birds that take advantage of swarming insects, which are by nature found in local concentrations, colonial breeding can be a successful strategy.