and therefore humans have an interest in understanding the seasonal movements of bird populations. Birds are regarded as resident when they spend all year in the same area, and migratory if they move seasonally between the breeding and nonbreeding areas. Most birds of the tropics and some...
阅读理解Bird migration is described as the regular, seasonal movement of bird populations from one place to another and back again.The longer days and rich food of the northern summer provide greater chances for birds to feed their young. The longer daylight hours and enormous food resources allo...
英[ˈsi:zənl] 美[ˈsizənəl] 是什么意思 adj. 季节的,季节性的;周期性的;随季节变化的; 英英释义 seasonal[ 'si:zənəl ] n.a worker who finds employment only in certain seasons 同义词:seasonal worker adj.occurring at or dependent on a particular season ...