|
The bee-eaters are a group of near-passerine birds in the family Meropidae. Most species are found in Africa and Asia but others occur in southern Europe, Australia, and New Guinea. They are characterised by richly coloured plumage, slender bodies, and usually elongated central tail feathers. All have long downturned bills and pointed wings, which give them a swallow-like appearance when seen from afar. There are 26 different species of bee-eaters. As the name suggests, bee-eaters predominantly eat flying insects, especially bees and wasps, which are caught in the air by sallies from an open perch.〔 While they pursue any type of flying insect, honey bees predominate in their diet. Hymenoptera (ants, bees and wasps) comprise from 20% to 96% of all insects eaten, with honey bees comprising approximately one-third of the Hymenoptera.〔 In the Hymenoptera order, the specific species Apis dorsata is commonly eaten by these birds. These bees attempt to congregate in a mass defense against these birds. Before eating its meal, a bee-eater removes the stinger by repeatedly hitting and rubbing the insect on a hard surface. During this process, pressure is applied to the insect thereby extracting most of the venom.〔 Notably, the birds only catch prey that are on the wing and ignore flying insects once they land. Bee-eaters are gregarious. They form colonies by nesting in burrows tunnelled into the side of sandy banks, such as those that have collapsed on the edges of rivers. Their eggs are white and they generally produce 2–9 eggs per clutch (depending on species). As they live in colonies, large numbers of these holes are often seen together, white streaks from their accumulated droppings accentuating the entrances to the nests. Most of the species in the family are monogamous, and both parents care for the young, sometimes with the assistance of other birds in the colony, a behavior considered unusual for birds.〔 ==Description== The bee-eaters are a fairly uniform group, morphologically. They share many features with related Coraciiformes such as the kingfishers and rollers, being large-headed (but not as large-headed as their relatives) short-necked, brightly plumaged and short-legged. Their wings may be rounded or pointed, with wing shape closely correlated with foraging habitat and migratory tendencies. Shorter, rounder wings are found on species that are sedentary and make shorter foraging flights in denser forests and reedbeds. Those with more elongated wings are more migratory. All the bee-eaters are highly aerial. They take off strongly from perches, fly directly without undulating, and are able to change directions quickly. Bee-eaters rarely hover, however. The bills of bee-eaters are curved, long and end in a sharp point. The bill can bite strongly, particularly at the tip, and is used as a pair of forceps with which to snatch insects from the air and crush smaller ones. The short legs have weak feet, when moving on the ground its gait is barely more than a shuffle. The feet have sharp claws used for perching on vertical surfaces and also during nest excavation.〔 The plumage of the family is generally very bright and in most species dominated or at least partly green. The two carmine bee-eaters are mostly rosy coloured. Most of the ''Merops'' bee-eaters have a line through the eye and many have differently coloured throats and faces. The extent of the green in these varies from almost completely in the green bee-eater to barely any in the white-throated bee-eater. Three species, from equatorial Africa, have no green at all in their plumage, the black bee-eater, the blue-headed bee-eater and the rosy bee-eater. Several species have long streamers in the tail, and in a few species these are ended with expanded spatulae.〔 There is little visible difference between the sexes in most of the family. In several species the iris is red in the males and brown-red in the females, and in species with tail-streamers these may be slightly longer in males. Both the European and red-bearded bee-eaters have differences in the colour of their plumage, and the rainbow bee-eaters have differently shaped tail-streamers.〔 There are however probably undocumented instances where bee-eaters are sexually dichromatic in the ultraviolet end of the colour spectrum, which humans cannot see. A study of blue-tailed bee-eater found that males were more colourful when comparisons between males and females included a comparison of their plumage in the UV spectrum. Overall colour also was affected by body condition, suggesting that there was a signalling component to plumage colour.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bee-eater」の詳細全文を読む スポンサード リンク
|