Birds (class Aves or clade Avialae) are feathered, winged, two-legged, warm-blooded, egg-laying vertebrates. Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. Extant birds have more or less developed wings; the most recent species without wings was the moa, which is generally considered to have become extinct in the 16th century. Wings are evolved forelimbs, and most bird species can fly. Flightless birds include ratites, penguins, and diverse endemic island species. Some species of birds, particularly penguins and members of the Anatidae family, are adapted to swim. Birds also have digestive and respiratory systems that are uniquely adapted for flight. Some birds, especially corvids and parrots, are among the most intelligent animal species; several bird species make and use tools, and many social species culturally transmit knowledge across generations.
圖片編號:
49972168
拍攝者:
Serdex94
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授權類型 | 尺寸 | 像素 | 格式 | 點數 | |
---|---|---|---|---|---|
標準授權 | XS | 480 x 318 | JPG | 13 | |
標準授權 | S | 800 x 530 | JPG | 15 | |
標準授權 | M | 2465 x 1633 | JPG | 18 | |
標準授權 | L | 2747 x 1819 | JPG | 20 | |
標準授權 | XL | 3475 x 2302 | JPG | 22 | |
標準授權 | MAX | 4256 x 2819 | JPG | 23 | |
標準授權 | TIFF | 3486 x 2309 | TIF | 39 | |
進階授權 | WEL | 4256 x 2819 | JPG | 88 | |
進階授權 | PEL | 4256 x 2819 | JPG | 88 | |
進階授權 | UEL | 4256 x 2819 | JPG | 88 |
XS
S
M
L
XL
MAX
TIFF
WEL
PEL
UEL
標準授權 | 480 x 318 px | JPG | 13 點 |
標準授權 | 800 x 530 px | JPG | 15 點 |
標準授權 | 2465 x 1633 px | JPG | 18 點 |
標準授權 | 2747 x 1819 px | JPG | 20 點 |
標準授權 | 3475 x 2302 px | JPG | 22 點 |
標準授權 | 4256 x 2819 px | JPG | 23 點 |
標準授權 | 3486 x 2309 px | TIF | 39 點 |
進階授權 | 4256 x 2819 px | JPG | 88 點 |
進階授權 | 4256 x 2819 px | JPG | 88 點 |
進階授權 | 4256 x 2819 px | JPG | 88 點 |