On average, each species reached various stopping points 0.8 days earlier per degree Celsius of temperature increase. Some species' schedules accelerated by as much as three to six days for each rising degree. To date, the Northeast has experienced more relative warming than the Southeast.
According to the review, Hurlbert said, the speed at which a species migrates is the biggest influence on how strongly it responds to increasing temperatures. Slow migrators, such as the red-eyed vireo or the great crested flycatcher, were the most adaptable to changes. Additionally, the length of the migration path affects how quickly birds move from one location to another.
"It makes sense that if you take your time to move north, you're sort of checking out the surroundings around you," he said. "If the conditions seem too cold, you can decide there's no point in moving on that day. Species that tended to advance quickly, as well as those migrating from greater distances, such as Central or South America, were less able to adapt to temperature changes."
However, being a slow traveler does not free a species from all climate change-induced migration challenges. Because they stay in one spot longer, such birds have heavier habitat and food requirements, making them more dependent upon the resources that are available along their paths. That reliance could become a greater problem if climate projections for the next 50 years to 75 years hold true, Hurlbert said. Climatologists predict the Northeast will continue to warm at a faster pace than the Southeast, potentially forcing slow migrators to move even slower and put greater strain on their migratory routes.'/>"/>
|Contact: patric lane|
University of North Carolina at Chapel Hill