Isn't it fun to take off your sweaters (羊毛或尼龍?zhí)咨? and change into T-shirts every spring? Some birds change their \"clothes\"in spring， too. They do it by molting (換羽).Molting means losing old feathers and getting new feathers to replace them. New feathers push the old， worn feathers out of the bird's skin. Birds that live in harsh1 deserts and grasslands usually molt twice a year，in spring and in autumn.Their feathers wear out faster than those of other birds.Most other birds molt mainly in the fall.

Hiding from Enemies Molting may take five to twelve weeks to complete. Ducks lose their feathers quickly.They are not able to fly until the new wing feathers grow in.They have dull (色彩不鮮明的)feathers until then to help them hide. Some birds become a different color when they molt.Ptarmigans （雷鳥)have white feathers in winter，when snow covers the ground. In the summer they have brown feathers. Because their feathers change colors， ptarmigans can hide more easily all year long.

Looking for a Mate Often male birds wear more colorful feathers after their spring molt.That is when they are trying to attract a mate. Egrets(白鷺) grow long， flowing plumes2 during spring courtship3 season.They shed the plumes soon after.

Getting New Colors Some birds get a new color when the faded edges of their old feathers wear down. The inner part of the feather is a different color，and it begins to show. In spring， the male house sparrow （麻雀） gets his black \"bib\" in just that way. Keep an eye on the birds you see around your yard. Maybe you'll catch them \"changing their clothes.\"

每年春季脫下毛衣?lián)Q上T恤衫是不是很有意思？一些鳥兒也在春季換“衣服”。它們脫換羽毛。換毛意味著脫去舊的羽毛，長出新的羽毛。新羽毛從鳥的皮膚里長出來，替換已磨損的舊羽毛。生活在環(huán)境惡劣的沙漠和草原的鳥通常一年換毛兩次，分別在春季和秋季。它們的羽毛比其他鳥的羽毛磨損快。其他大多數(shù)鳥主要在秋季換毛。

躲避敵人換毛要花掉5~12周。鴨子脫毛很快。在翅膀上的羽毛長好以前它們是不能飛的。在此以前它們會用顏色灰暗的羽毛來幫助隱藏自己。一些鳥在換毛時(shí)會變成另一種顏色。雷鳥的羽毛在白雪覆蓋的冬天是白色的，在夏天則是棕色的。正是因?yàn)樗鼈兊挠鹈梢宰兩坐B全年都能更容易地躲起來。

求偶雄鳥春季換毛后長出更鮮艷的羽毛，這正是他們吸引雌鳥的時(shí)候。白鷺在春季的求偶期長著一身長而流暢的羽毛。求偶期一過它們就脫毛。

變換新的顏色一些鳥在舊羽毛的邊緣退色磨損時(shí)，會變生出新的顏色。羽毛的內(nèi)部是另一種顏色，并開始顯現(xiàn)。春天，雄性家麻雀就是以這種方式長出嘴角下形似圍涎的那撮黑毛。觀察一下你院子周圍的鳥。也許你剛好能趕上它們“換衣服”。

注釋：

1．harshadj．艱苦的，惡劣的

2．plume n．羽毛

3．courtship n．求愛期