Alaska's iconic caribou herds appear to be surviving changes in the Arctic climate, despite shifts in the time periods during which their food supplies are most plentiful, according to a recent study.

The report indicated that Alaska caribou apparently aren't facing what is known as a mismatch, a phenomenon created when caribou give birth to calves at a similar time each year, while a warming climate causes food supplies to peak earlier in the year.

Such mismatches, with reduced survival of offspring, were suggested in studies of western Greenland but not in other parts of the Arctic, according to the report by the U.S. Geological Survey, the Alaska Department of Fish and Game, and two universities.

"We observed long-term changes in temperatures, timing and the length of the growing seasons, but found little support for a mismatch between caribou and the plants they consume," noted Dave Gustine, lead author of the USGS study, who is now working with the National Park Service.

Researchers studied caribou food supplies along a 124-mile region of the Dalton Highway, a gravel road that provides the only land-based link between Alaska's North Slope oil fields and Fairbanks in central Alaska.

The Alaska Department of Fish and Game originally examined that region in the 1970s to understand the foods important to the Central Arctic herd, which is the primary caribou population inhabiting the area along the highway.

The most recent study noted that Arctic thaw is occurring one to two weeks earlier than the first study, and the North Slope growing season is lengthening by 15 to 21 days. At the same time, however, caribou are maintaining the same reproductive timeline.

Despite the warming climate, the report hypothesized, "earlier springs, increases in forage biomass, longer growing seasons, and shifts in forage quality in summer-autumn ranges will provide nutritional benefits throughout the growing season to reproductive females."

Layne Adams, a research wildlife biologist with the USGS and co-author of the study, concluded that "given the wide variability in the quality of plants used by caribou for food across northern Alaska and the capacity of migratory caribou to shift birthing and summering ranges, we expect a continued and diverse response among populations of caribou into the future."

The study was published last month in PLOS ONE.

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at