What birds can teach us about climate change

I must admit that I don’t know a lot about birds but I do know that they can be harbingers of change. I have been looking at the Royal Society Protection of Bird’s website and at the Chaffinch in particular, because it is a pretty yellow gold bird, and when I played the chaffinch song for the web site it sounded familiar and delightful. I see that chaffinch eat seeds and insects, and cover most of England Wales and Scotland. There are either 313,000 breeding pairs (although other sources say 200,000 pairs). Most Chaffinch migrate to Spain for the winter but recently more chaffinch than normal chose to stay in this country.