They need to preen their flight feathers, 它们要整理飞羽

276. Pigeons are by far the most successful urban bird.
     鸽子是目前最成功的城市鸟类
277. Here, in Albi, in the south of France,
     在法国南部的阿尔比
278. the pigeons come to the river to bathe.
     鸽群飞到河边沐浴
279. They need to preen their flight feathers,
     它们要整理飞羽
280. clean off the city dust,
     清洗掉城市的灰尘
281. and cool themselves down.
     并给自己降降温
282. But death lies in wait.
     而死神正埋伏以待

来自《行星地球 第二季 第六集 Planet Earth S02E06 城市》第 279 行