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
Handbook of the Birds of the World a non-profit endeavour fuelled by material from more than one hundred contributors from around the world. In early 2013, Lynx Edicions launched the online database HBW Alive, which includes the volume and family introductions and updated species accounts from all 17 published HBW volumes. Since its launch, the taxonomy has been thoroughly revised and updated twice (once for non-passerines and once for passerines), following the publication of the two volumes of the "HBW and BirdLife International Illustrated Checklist of the Birds of the World". The Handbook of the Birds of the World Alive site also provides a free access 'Key