hummingbird(redirected from Trochiliformes)
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hummingbird,common name for members of the family Trochilidae, small, strictly New World birds, related to the swifts, and found chiefly in the mountains of South America. Hummingbirds vary in size from a 2 1-4-in. (6-cm) fairy hummingbird of Cuba (the smallest of all birds) to an 8 1-2-in. (21.6-cm) giant hummer of the Andes, Patagona gigas. Their colors are brilliant and jewellike; the feathers have a prismatic construction that iridesces in changing light. Hummingbirds feed on insects and the nectar of flowers, for which their long, slender (sometimes curved) bills are especially adapted. The beaks are also used in fights between hummingbirds. They are usually seen hovering or darting (at speeds of up to 60 mi/97 km per hr) in the air as they feed in flight; their weak feet cannot support them on flat surfaces. Their wingbeats are so rapid (50–75 beats per sec) that the wings appear blurred. The enormous amount of energy expended on this continuous movement is supported by constant feeding; at night they lapse into a state of torpor like that of animals in hibernation. The nests vary but are usually tiny cups of soft vegetation fastened to the top of a branch. Several species are found in the W and SW United States, e.g., the black-chinned hummingbird and the calliope hummingbird, the smallest (3 in./7.6 cm) of the U.S. species. The only species found in the NE United States is the ruby-throated hummingbird, Archilochus colubris. The male is metallic green above and whitish below, with an iridescent ruby-red throat; the female is dull-colored. The sunbirds, small and brilliant passerine birds of India, Africa, and Australia, are sometimes called hummingbirds in those areas but belong to a different taxonomic order (Passeriformes). Hummingbirds are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
..... Click the link for more information. , subphylum Vertebrata, class Aves, order Apodiformes, family Trochilidae.
any one bird of the suborder Trochili of the order Apodiformes. The suborder consists of one family (Trochilidae) comprising 319 species.
Hummingbirds are distributed in America from southern Alaska and Labrador to Terra del Fuego, being particularly diverse in the tropics. They measure from 5.7 to 21.6 cm long and weigh from 1.6 to 20 g. The plumage of the male is usually extremely brilliant; the females are much less brilliant. The flight of the birds is rapid (up to 80 km/hr) and highly maneuverable, reminiscent of the flight of hawkmoths. Small species of hummingbird produce a humming sound with their wings, which are beaten at a rate of as much as 80 times per second (large birds make only eight to ten beats). The birds feed on flowers, sucking out the nectar while hovering; they also gather insects and spiders on plants or catch them in midair.
The enormous expenditure of energy for flight and the heat loss are compensated for by caloric food, such as nectar. Hummingbirds cannot maintain their intensive metabolism around the clock. Therefore, at night, in the cold, or when there is insufficient food they fall into a torpor. In this state the body temperature falls from 39°–43°C to 14.5°-21°C and metabolism is sharply reduced.
Hummingbirds live wherever there are flowers—in deserts, orchards, forests, and mountain meadows—from sea level to 4,500 m (in the Andes). Migratory birds, they leave for the winter from the northernmost and southernmost parts of their area of distribution; they leave the desert during periods of drought. They are polygamous. The female builds the nest, incubates the eggs, and feeds the young. Nests are built on trees and bushes; some species cement their nests with saliva to rocks or leaves just as the swifts do. Two eggs are laid and incubated 14–19 days. Hummingbirds are beneficial as pollinators of plants. The numbers of many species have been sharply reduced as a result of mass exterminations for the use of the skins as decoration.
REFERENCEZhizn ’ zhivotnykh, vol. 5. Moscow, 1970.
A. I. IVANOV
Google algorithmThe formula Google uses to rank the resulting Web pages from a user's query. Along with the PageRank system that was Google's major contribution to evaluating website importance due to popularity, Google uses numerous other criteria that change periodically to deliver more relevant results as well as to prevent people from gaming the system. For example, if one criterion were the quantity of identical words in the page, search engine optimization (SEO) specialists might embed multiple occurrences of the word in the page that are invisible to the user but not to the search engine spider that crawls the Web. When Google finds that people are doing excessive "keyword stuffing," it may lessen the value of that criterion in the overall mix.
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