(Credit: zizar/Shutterstock) Should I stay, or should I go? It's a question we might imagine birds asking themselves every time the seasons change. Many, of course, do decide to leave, packing up for warmer or cooler climes, depending on the time of year. But many, the majority, in fact, don't migrate. The old adage might be true after all. If you stay there will be trouble — but if you go, it'll be double.
What then, is the deciding factor for the birds? Many species migrate to northerly breeding grounds in the summer, where resources can be more abundant for them and their young. When winter comes, the cold kills off the food and they return to warmer climes. But, as we've pointed out, many birds don't have to do this at all — they breed and feed in the same regions all year round. The choice, it turns out, ...
