Researchers have been tracking bird migration for many years but the biggest changes have come in the last fifty or so. According to the Science Daily, birds in Canada and Europe are moving northward a bit earlier each year. Birds that breed on the early end are hurrying up their passage while those that breed later are taking their time. What this means is that the entire migration period has been extended by about a week. The time difference is the greatest in Europe which has warmed faster than Canada. But the pattern is pretty much the same the world over. Audubon has a good article on U.S. birds.
The problem is, of course, is that birds, for eons of evolutionary time, have migrated north as the daylight increases, not with the weather. Overall, that’s the best strategy. But for any one species, some birds leave earlier, and the tardier ones lag behind. But this puts the birds where they need to be as the insects, flowers, and seeds, responding to soil warmth, are coming out, producing food for the birds. But if the climate warms, the bugs and seeds come out earlier and the birds, arriving at the usual time, miss out. So now the early birds in every species are at an advantage. But it’ll take many years, probably many decades, for birds to adjust their migration timing. If only some species have adjusted their migration timing by one week in fifty years, how many more years will it take for other birds? Some birds may not adjust at all.
To make matters worse, global warming keeps getting worse because it is speeding up. Birds are just not going to be able to keep up. And it’s not just the timing of migration. There have been episodes of mass bird deaths due to excessive heat, especially in desert environments. As the world warms, birds are going to have to drink more water as they will lose it faster. Smaller birds will be most affected. Fifty years from now, at this rate, things will be much worse for all birds. Birdlife DataZone has some interesting information on this as does Audubon.
But I’m probably not telling you anything new. I was just reminded of the controversy (still a controversy) about global warming in letters to our local paper. How people can believe that global warming is a hoax is beyond me. Note that 99% of climate scientists, every single major scientific organization in the world, the Nobel Prize Committee, and the governments of 190 countries accept the fact of climate change and that the earth’s warming is due to the increase in carbon dioxide from human activity. How can anyone not accept that? I used to be appalled at the fact that a large minority of Americans do not believe in evolution. More, in fact, believe in psychic powers like ESP than evolution. That doesn’t make me very hopeful that we can save the birds from a hot earth anytime soon.
P.S. About a year ago I reported on this subject in another blog, but decided that a reiteration makes sense.