As feathers became larger over time, flapping flight evolved and birds finally became fully air-borne.
随着时间的推移，羽毛变得越来越大，扑翼飞行逐渐发展，鸟类最终完全可以在空中飞行。
As we've discussed, birds are apparently descendants of dinosaurs and shared many commonalities with some dinosaur species, like feathers and maybe even flight and of course egg laid.
正如我们讨论过的，鸟类显然是恐龙的后代，与一些恐龙物种有许多共同之处，比如羽毛，甚至飞行，当然还有产卵。
And of course they aid flight-but not always, as ostriches and penguins, which have feathers but do not fly, demonstrate.
当然，羽毛还能辅助飞行——但这也并非绝对，鸵鸟和企鹅虽然也拥有羽毛，但却不会飞行。
Small birds molt once or twice a year, and they replace their 9 or 10 primary flight feathers a few at a time over the course of a few weeks.
小型鸟类一年进行一到两次换羽，在换羽期间，它们一次会替换掉9到10根左右的飞羽，而这个过程将持续几周时间。
He added that, since these ancient feathers didn't aid flight, they likely served for purposes of animal communication, mating, and warmth.
他补充道，远古时期的羽毛并不用于飞翔，而是起到与其他动物沟通、求偶及取暖的作用。
It could be that dinosaurs with more primitive feathers used them for temperature regulation, camouflage and visual signaling, rather than flight.
拥有更为原始的羽毛的恐龙，当初可能将其用于调节身体温度、伪装和发出视觉信号，而非辅助飞行。
The males courted the females by means of nuptial flight, displaying nuptial feathers, feeding and courtship nesting.
求偶方式主要有婚飞、显示饰羽、求偶喂食和象征性营巢行为；
Many of the feathers seem to be small, brown and fluffy - probably for warmth rather than flight.
许多羽毛看上去是细小的褐色蓬松的茸毛，可能主要是用于保暖，而不是用于飞行。
Small birds molt once or twice a year, and they replace their 9 or 10 primary flight feathers a few at a time over the course of a few weeks.
形体小的鸟儿一年脱羽一到两次。它们有9到10只主要用于飞行的羽毛，鸟儿们一次更换几只，在几周的时间内它们就可以完成更换。
Upperwing has pale greyish-white primary bases and often pale rufous or yellowish-brown forewing, paler than dark grey flight-feathers.
翼上初级飞羽呈现灰白色，翼前缘经常为淡棕色或黄棕色，比飞羽的深灰色要浅。
Many of the feathers seem to be small, brown and fluffy - probably for warmth rather than flight.
许多羽毛看上去是细小的棕色的茸毛，可能主要是用于保暖，而不是飞翔。
Many of the feathers seem to be small, brown and fluffy - probably for warmth rather than flight.
许多羽毛看上去是细小的棕色的茸毛，可能主要是用于保暖，而不是飞翔。
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