Climate Change Miscues May Shrink Species’ Outer Limits
Throughout the world, climate change is causing age-old ecological partners to miss their cues as seasons shift. The trend may be so strong at higher latitudes that researchers now propose that some species’ ranges could actually shrink away from the poles.
This idea comes from studying broad-tailed hummingbirds that migrate north from Central America each spring to high-altitude breeding sites in the western United States. With only brief mountain summers to raise chicks, male hummingbirds typically arrive in the region before the first flowers bloom and scout for territories. Around the Rocky Mountain Biological Laboratory in Gothic, Colo., near the upper limit of the broad-tailed hummingbird breeding range, the gap between the first hummingbird arrival and the first bloom has narrowed by roughly 13 days during the last four decades. Amy McKinney of the University of Maryland in College Park and her colleagues report the discovery online in Ecology.