UNIVERSITY PARK, Pa. — Mountain hares in Scotland that rely on camouflage to escape predators are becoming increasing mismatched to their surroundings due to less snowy winters, a new study shows. Mountain hares are one of several species that molt from a dark coat in summer to a white coat in winter to maintain camouflage against snowy landscapes. But due to climate change, the duration of snow cover is decreasing — creating a “mismatch” in seasonal camouflage that could expose the hares to predators.
The study, by an international team of researchers including a Penn State biologist, appears Dec. 16 in the journal Proceedings of the Royal Society B.
“Organisms have important life events that are timed to seasonal changes in the environment, like bird migration or hares molting to a white coat in winter,” said Sean Giery, Eberly Postdoctoral Research Fellow at Penn State and an author of the paper. “The ability to adapt this timing in the face of human-induced climate change could determine whether the species can persist in our changing world.”
The researchers suggest that the observed lack of change in the timing of mountain hares’ molt — with more white hares on a snowless background — could eventually endanger the species’ survival in Scotland.
Key to the mountain hare study were published historical datasets by Adam Watson and John Flux that describe the seasonal molt of wild mountain hares in the Scottish Highlands during the 1950s and 1960s. These earlier studies represent the longest running systematic historical survey of molt timing in any species.
The research team returned to the Scottish Highlands to carry out surveys and record the pattern and timing of molt over multiple spring and fall seasons. This allowed them to compare the present and the historical timing of the hares’ color molts. Further, by employing statistical analysis, the researchers calculated the change in temperature and snow cover over the past 65 years within the study region.