初冬大雁南飞,春天又是一幅“新燕啄春泥”的繁忙景象。看到窗外树上正忙于筑巢的鸟儿,或凝视鸟儿迁走而留下的空巢,我们不禁要问:今年在树上做窝的鸟儿还是去年的那一群吗?今年迁走的鸟儿明年还会回来吗?鸟儿是怎样克服种种困难,越过海洋和高山,飞过那么远的距离又找到自己的老家呢?这些真是让人神往的谜。 The early winter geese fly south, and in spring it is a busy scene of “new Yanyan spring mud”. When we see the birds that are busy building nests on the trees outside the window, or we gaze at the empty nests left by the birds, we can’t help but ask: Are the birds that made nests in the trees this year still the group last year? Will the birds come back next year? How do birds overcome various difficulties, cross the oceans and mountains, fly far behind and find their own hometown? These are really fascinating mysteries.