Gleaning (birds) World flycatchers, Tyrant flycatchers, babblers, Old World warblers, New World warblers, Vireos and some hummingbirds and cuckoos. Many birds make use of multiple feeding strategies, depending on the availability of different sources of food and opportunities of the moment. Foliage gleaning, the strategy of gleaning over the leaves and branches of trees and shrubs, can involve a variety of styles and maneuvers. Some birds, such as the common chiffchaff of Eurasia and the Wilson's warbler of North America, feed actively and appear energetic. Some will even hover in the air near a leaf or twig while gleaning from it; this
Birds of the Danube Delta and especially of feeding the deltaic biotopes are providing in the warm season of the year. This phenomenon is also supported by the presence – in different deltaic biotopes as against the common ones – of some species, which in the rest of their area cover other life environments. The species of non-brooding deltaic birds were classified into the biotopes they visit while resting on the Danube Delta's territory and they are connected to by the way these biotopes are providing their food. The ornithological biotopes of the Danube Delta belong to three well-individualized habitats, namely the aquatic, the amphibian