Male arctic ground squirrels reach puberty every year. As if that wasn’t hard enough, now the females have a problem too.
According to an article published Thursday in the journal Science, climate change seems to be bringing them out of hibernation sooner. This is important, as it could disrupt the timing of the animals’ mating cycle.
Typically, males emerge from hibernation before females to prepare for the spring mating season. They need time to regain their sexual maturity, each year, because their testosterone levels drop sharply during the winter.
Then the females wake up. But scientists have found that as temperatures rise, female ground squirrels emerge up to 10 days earlier than before. The researchers think it has to do with the earlier thawing of the ground.
The hibernation pattern of males, meanwhile, does not seem to change.
“This study suggests that males and females of the same species may respond differently to climate change,” said Helen E. Chmura, a United States Forest Service ecologist researcher and lead author of the paper. “This could have important implications for reproduction.”
The squirrel problems are part of a much larger crisis. All over the world, wildlife is in trouble. On earth, the main cause is that humans are taking over too much of the planet, wiping out the biodiversity that was there before. In the oceans, the main problem is overfishing. Climate change makes survival even more difficult.
For now, arctic ground squirrels are still abundant in the wild. The International Union for Conservation of Nature classifies them as species of least concern, which means that they are neither threatened nor in need of conservation efforts. But the paper says the new hibernation mismatch “has the potential to affect their likelihood of survival.”
Any decline in squirrel populations could disrupt the local food web. Almost all Arctic predators, from wolves to eagles, depend on it as a food source.
Although the Arctic is warming faster than any other region on Earth, there is relatively little research on how this warming affects animals. This new paper, which covers more than 25 years in northern Alaska, is one of the first long-term research projects to present strong evidence that warming is directly altering physiological processes in Arctic species.
“This study is relatively unusual because it shows that warming has a direct impact on a mammal,” said Cory T. Williams, assistant professor at Colorado State University and co-author of the study. “Some people might say, ‘OK, 10 days ahead of 25 years doesn’t seem that fast.’ But in terms of climate, it’s incredibly fast.
Arctic ground squirrels may look cute, but the males can be very territorial. They engage in many fights during the mating season, some fatal. They have tails, but not long and bushy like the squirrels found further south. And they emit distinctive whistles that could easily be mistaken for the chirping of a small bird. Some Alaska Natives call them parka squirrels because their fur forms a nice warm fringe for the hood of a coat.
Scientists have long been interested in their hibernation patterns.
During the long winter sleep, squirrels’ core body temperature can drop to around 27 degrees Fahrenheit, or about minus 3 degrees Celsius, with their resting heart rate dropping as low as three beats per minute. Better knowledge of this process could lead to advances in therapeutic hypothermia, a medical treatment in which body temperature is lowered to prevent injury. It is sometimes used after cardiac arrest.
But the most pressing challenge, scientists say, is getting a handle on the changes happening in the Far North.
“The big gap is just understanding what’s going on in the Arctic in general,” Dr Williams said. “This study shows why we need long-term projects to understand the changes happening at different levels.”