| Mixed-species Feeding Flock |
Website Links For Feeding |
Information AboutMixed-species Feeding Flock |
| CATEGORIES ABOUT MIXED-SPECIES FEEDING FLOCK | |
| ornithology | |
|
A Proverb says, "Birds of a feather flock together," but birds of different kinds often occur together. They may do so at rich food sources (as animal carcasses, Termite hatches, Garbage Dump s, fruiting or flowering trees, schools of fish) or simply because they share habitat and tolerate each other, as many Shorebirds , Gull s, Duck s, Starling s, and Icterid s do. They may also travel together. Many seed-eating birds ( Finch es, Sparrow s, Bunting s, etc.) feed in mixed flocks, often with closely related species, in grassland or scrub. However, mixed feeding flocks are particularly common in Forest s. In the North Temperate Zone , they are typically led by Tits and Chickadees , often joined by Nuthatch es, Treecreeper s, Woodpecker s such as the Downy Woodpecker and Lesser Spotted Woodpecker , Kinglet s, and (in North America) New World Warbler s—all Insect-eating birds. They are particularly common outside the breeding season. Insectivorous feeding flocks reach their fullest development in tropical forests, where they are a typical feature of bird life. In the Neotropic s the leaders or "core" members may be Black-throated Shrike-tanager s in southern Mexico , Three-striped Warbler s in Central America , and Antbird s such as the Bluish-slate Antshrike in South America . Core species often have striking plumage and calls that attract other birds. Other members may come from most of the region's families of small diurnal insectivorous birds; exceptions include Swift s, Swallows , and Gnateater s. However, not all birds of these families join mixed flocks. There are genera such as s of the genus '' Cyanolyca '' flock with Unicolored Jay s and Emerald Toucanet s. Many icterids associate only with related species, but the western subspecies of the Yellow-backed Oriole associates with jays and the Band-backed Wren . Flocks wander at about 0.3 kilometers per hour through the forest, with different species in their preferred niches (on the ground, on trunks, in high or low foliage, etc.) Some species follow the flock all day, while others (such as the Long-billed Gnatwren ) join it only in their own territories. Mixed-species flocks on other continents resemble those of the Neotropics. The core members in Africa are often tits; in Asia Babbler s, Drongo s and Green Iora s; in Australasia members of the family Pardalotidae such as Gerygone s in New Guinea and Fairy-wren s and Thornbill s in Australia . As in the Americas, they are joined by birds of other families such as Minivet s and Bulbul s. In tropical Asia, where this phenomenon is arguably best developed, flocks may number several hundred birds spending the entire day together, and an observer in the Rain Forest may see virtually no birds except when encountering a flock. For example, as a flock approaches in the Sinharaja Forest Reserve in Sri Lanka , the typical daytime quiet of the jungle is broken by the noisy calls of Orange-billed Babbler s and a Greater Racket-tailed Drongo . As the birds pass, the observer can glimpse the quieter, more inconspicuous, members of the flock. If the flock crosses a track, its true numbers become clearer. The two Laughing Thrushes become ten, and the previously missed small species, like Kashmir Flycatcher and Velvet-fronted Nuthatch , reveal themselves. Though the Sinharaja reserve is large and ecologically important, most of the passerines there are concentrated into six or seven mobile flocks. In smaller patches of jungle, nearly all may occur in just one flock. The advantages of this behavior are not certain, but evidence suggests that it confers some safety from predators, especially for the less watchful birds such as vireos and woodpeckers, and also improves feeding efficiency, perhaps because arthropod prey that flee one bird may be caught by another (Ehrlich et al.). REFERENCES EXTERNAL LINKS
|
|
|