Humans don't have hollow bones like birds do, so how big would our wings have to be to lift us off the ground?

“Birds routinely fly in high winds close to buildings and terrain — often in gusts as fast as their flight speed,” Windsor said. “So the ability to cope with strong and sudden changes in wind is ...

If the wind is blowing behind them, the birds fly high up in the sky where the wind will increase their speed. Do birds migrate to Northern Ireland? Birds do migrate to Northern Ireland!