(verb) A type of foraging during which a bird will deliberately and methodically pick over an area to collect food, typically insects or seeds. Gleaning birds on tree trunks, for example, will examine many crevices in the bark to search for insects, moving along the trunk as they feed. Other areas birds may glean are the undersides of leaves, on the heads of flowers or in leaf litter. Depending on the bird, they may also hover while they glean, picking several insects from one area before landing to consume them. This differs from hawking in that the insects are not caught in midair.
Birds that frequently practice gleaning include warblers, woodpeckers, nuthatches, kinglets and creepers. Both insectivorous and granivorous birds may be gleaners, though their methods and locations of gleaning will vary based on the food source.
Gleaning birds offer birders a great opportunity to observe foraging. Because this is a very deliberate behavior, it can be easy to watch the birds and see them move to different angles and positions for good views of different field marks for proper bird identification. To make the most of gleaning birds, observe the same area carefully and watch for multiple birds to take advantage of the best feeding spots.
Photo – Brown Creeper © J Jongsma