鳥は巣をつくる。の英語

Birds build nests.

Birds build nests.

A bird builds （a nest）

A bird builds （its nest）.

A bird builds a nest.

A bird builds （its nest） in a tree.

of a bird, to stay in the nest to incubate eggs

Birds roost―go to roost―fly home to roost.

gather birdnests

The young birds leave the nest.

A hen broods―sits （on eggs）―incubates.

The birds are flying around.

The bird are flying around.

hunting for birds' nests to get the eggs

a bird that has built (or is building) a nest

Birds sing.

Let the bird fly away!

Set the bird free!

Bird is singing.

set a bird free from a cage

The birds are at roost.

A bird roosts―goes to roost.

Birds lay eggs.

The birds are singing in the trees.

Let the bird fly away.

The bird flapped its wings

to go bird-nesting

an act of a bird flapping its wings

A bird folds its wings.

young bird not yet fledged