Birds on the Move
By Katrina Marland
Every year around the holidays, the Audubon Society organizes the annual Christmas Bird Count, an event in which volunteers across the U.S. help take a census on the birds that appear in their regions. A new study published in the Journal of Animal Ecology has used the data from 35 years of this Christmas Bird Count to find the rate at which certain bird species are adjusting to rising temperatures. What it found was both good and bad.
For the most part, all signs point to birds moving north. Not just moving south for the winter and north for the summer, but generally shifting their ranges north to compensate for the changing climate. It doesn’t happen quickly, of course. It takes several years for an entire species to change their preferred range. Since birds fly, often for long distances, they are among the most mobile of all animals, and a good baseline to measure against. If birds can make it to cooler climates in time, maybe other species can too, if they move fast enough. But that’s the problem. It seems even some birds aren’t moving quite fast enough.
The study found that many birds take roughly 35 years to adjust to a change in climate. The research covered a total of 59 different bird species, one of them being the black vulture. This bird’s range has shifted north quite a bit in the last 35 years. Now, they spend their winters as far north as Massachusetts, where today’s winter temperatures are about the same as Maryland’s were back in 1975.
Sadly, that’s where the good news ends because many species aren’t keeping up with the rate of change. Some species, despite severe changes in their native range’s climate, aren’t moving at all. Or if they are, they’re going far too slow. The endangered red-cockaded woodpecker hasn’t moved its range at all in the last 35 years. That is because the bird only makes its home in longleaf pine forests, which are found only in select locations and aren’t moving north with the warming climate.
There are many birds like this that depend on certain species to survive — usually trees. Whether they require a specific species to live in or seeds to eat, their fate is tied to that of the trees, and unlike the birds that rely on them, the forests can’t migrate to a spot hundreds of miles away over the course of one winter. Which leaves birds with an unpleasant choice: make their way in a new type of habitat that they aren’t familiar with — you can imagine how happy the birds native to that ecosystem will be about their new neighbors — or struggle with increasing temperatures at home.