Climate Change's Impact

As warmer winter temperatures become more common, one way for some animals to adjust is to shift their ranges northward. But a new study of 59 North American bird species indicates that doing so is not easy or quick - it took about 35 years for many birds to move far enough north for winter temperatures to match where they historically lived. The researchers used 35 years of data from the North American Christmas Bird Count to match winter temperatures to where birds were seen. They tested 59 bird species individually and found that they responded differently to climate change. When summarised across bird species, there was evidence for a strong delay lasting about 35 years. For example, black vultures have spread northward in the last 35 years and now winter as far north as Massachusetts, where the minimum winter temperature is similar to what it was in Maryland in 1975. In contrast, the endangered red-cockaded woodpecker did not alter its range at all despite the warming trend, possibly because its very specific habitat requirements precluded a range shift.