Many birds are arriving earlier each spring as temperatures warm along the East Coast of the United States. However, the farther those birds journey, the less likely they are to keep pace with the rapidly changing climate.
Scientists at Boston University and the Manomet Center for Conservation Sciences analyzed changes in the timing of spring migrations of 32 species of birds along the coast of eastern Massachusetts since 1970. Researchers at Manomet gathered this data by capturing birds in mist nets, attaching bands to their legs, and then releasing them. Their findings, published in Global Change Biology, show that eight out of 32 bird species are passing by Cape Cod significantly earlier on their annual trek north than they were 38 years ago. The reason? Warming temperatures. Temperatures in eastern Massachusetts have risen by 1.5 degrees Celsius (2.7 degrees Fahrenheit) since 1970.
Species, such as the swamp sparrow, that winter in the southern United States are generally keeping pace with warming temperatures and earlier leafing of trees. They migrate earlier when temperatures are warm and later when spring is cool.
Birds that winter further south, like the great crested flycatcher, which spends its winters in South America, are slow to change, though. Their migration times are not changing, despite the warming temperatures in New England.
There appears to be good reason for the difference between the short- and long-distance migrants. Because temperatures are linked along much of the East Coast of the United Statesan early spring in North Carolina is generally an early spring in Massachusettsthe short-distance migrants can gain insight into when it will be warm further north. They can follow the flush of leaves and insects all the way to their breeding grounds each year. Long-distance migrants, though, do not have any good cue for whether it will be an early or late spring on the northern stretches of their migr
|Contact: Lucy Mansfield|