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Birds' diets are varied and often include nectar, fruit, plants, seeds, carrion, and various small animals, including other birds. [77] The digestive system of birds is unique, with a crop for storage and a gizzard that contains swallowed stones for grinding food to compensate for the lack of teeth. [149]
The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. [1] Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird.
A close relationship between birds and dinosaurs was first proposed in the nineteenth century after the discovery of the primitive bird Archaeopteryx in Germany. Birds and extinct non-avian dinosaurs share many unique skeletal traits. [1] Moreover, fossils of more than thirty species of non-avian dinosaur with preserved feathers have been ...
They hold at least 11 morphological traits in common, which are not found in other birds. Many of these characteristics have been previously identified on flamingos, but not on grebes. [16] The fossil palaelodids can be considered evolutionarily, and ecologically, intermediate between flamingos and grebes. [17]
Use and duration of torpor vary among hummingbird species and are affected by whether a dominant bird defends territory, with nonterritorial subordinate birds having longer periods of torpor. [130] A hummingbird with a higher fat percentage will be less likely to enter a state of torpor compared to one with less fat, as a bird can use the ...
Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight.Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capable of very high metabolic rates and oxygen supply, permit the bird to fly.
Magpies are birds of various species of the family Corvidae.Like other members of their family, they are widely considered to be intelligent creatures. The Eurasian magpie, for instance, is thought to rank among the world's most intelligent creatures, [1] [2] and is one of the few nonmammalian species able to recognize itself in a mirror test. [3]
Ratites (/ ˈ r æ t aɪ t s /) are a polyphyletic group consisting of all birds within the infraclass Palaeognathae that lack keels and cannot fly. [3] They are mostly large, long-necked, and long-legged, the exception being the kiwi, which is also the only nocturnal extant ratite.