Sea ice loss linked to decline in caribou in Greenland

UNIVERSITY PARK, Pa., Oct. 1 (UPI) -- Sea ice loss in the arctic may be causing fewer caribou calf births and higher calf mortality in Greenland, Penn State University scientists say.

The melting of arctic sea ice has been linked with changes in the timing of plant growth on land -- an increasingly earlier start to the plant growing season -- which in turn has been shown to be associated with lower production of calves by caribou in the area, they said.

Penn State biologist Eric Post said he has been studying the relationship between the timing of caribou calving and the start of the plant-growing season in Greenland for 20 years.

"I initially was interested simply in determining how closely timed the calving season was to the onset of vegetation green-up," he said, "without a thought as to how this relationship might be affected by climate change."

Archaeological evidence suggests caribou have used areas of Greenland as calving sites for more than 3,000 years, the researchers said, arriving from their west-to-east migratory journeys in search of young plants to eat around the time caribou give birth.

"Since plants are emerging earlier in the year, they tend to be older and past their peak nutritional value by the time the hungry caribou arrive to eat them," graduate student Jeffrey Kerby said. "The animals show up expecting a food bonanza, but they find that the cafeteria already has closed."

"This scenario is what we call a trophic mismatch -- a disconnect between the timing of when plants are most nutritious and the timing of when animals are most dependent on them for nutrition," he said.

The scenario needs more research, Post said.

"Sea ice is part of a broader climate system that clearly has important effects on both plants and animals," he said. "Exactly how sea-ice decline might affect species interactions in this and other types of food webs on land in the Arctic is a question that deserves greater attention."