The work was taken up during summer when the birds do not use the area.

Birds also use the river to find plants to eat or to fish in.

Birds use various techniques to get back down to Earth.

Many birds use this method when they are about to land.

These birds are using almost that much acceleration, and I don't see how they do it.

Near the end of the 1940s, he discovered that birds can use the sun as a compass.

I didn't know anything about the way some birds use warm air currents to help their flight.

But the birds also probably use their chorusing for defense.

The bird used the tip of his bill to make a mark on the feather.

So the birds use their considerable energy to engage in social communication instead.