hibernation

The fungus responsible for white-nose syndrome, an infectious disease that’s decimated bat populations across eastern Canada, is making rapid gains across the Prairies. Pseudogymnoascus destructans was detected last summer along Alberta’s Red Deer River, says Cory Olson, the coordinator of the Alberta Community Bat Program with Wildlife Conservation Society Canada. The fungus expanded more than 500 km in a one-year span, setting the stage for wider distribution into prime bat habitat in the Rocky Mountains.

Pseudogymnoascus destructans was first identified in eastern North America in 2006, likely arriving from Europe on clothing or equipment or from an infected bat on a cargo ship. The fungus spreads from bat to bat and thrives in cool temperatures. The infection irritates bats’ skin and disrupts hibernation, depleting their energy reserves and leading to starvation. Populations of little brown bats, northern bats (a.k.a. northern myotis), and tri-coloured bats have plummeted more than 90 per cent in affected areas as the fungus spreads west across the continent.

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But there could be hope on the horizon. European bats are resistant to white-nose syndrome, and Olson says there’s evidence that a small proportion of affected species in North America have tolerance as well. “Assuming their offspring are also resistant, these individuals could help populations recover, provided they can successfully reproduce,” he says. Meanwhile, little brown bats and northern bats were recently listed as endangered under Alberta’s wildlife act.

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Bats are critical in regulating insect populations, including mosquitoes and defoliators of forests and crops. Olson points to an American study which suggests bats provide the equivalent of billions of dollars worth of organic insect control each year. “Bats are important for the maintenance of healthy ecosystems and the loss of bats is likely to have important long-term consequences,” Olson adds. “We knew this fungus would eventually arrive in Alberta, and that a cultural shift in how people perceive bats, and manage them, was urgently needed. We need to do more to protect bats.”

A voice from the wilderness

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Every year as the temperature drops, hibernating animals, fattened from a summer spent gorging on food, prepare to hunker down for the winter. When they wake up in the spring, they’re healthy and strong despite months of inactivity. So how do they do it?

This was the question that Matthew Regan, an assistant professor of biology at the University of Montreal, and his colleagues set out to answer in a new study recently published in Science. Hibernation has long intrigued scientists, he explains. There was speculation that something in the gut helped some hibernators preserve muscle. Regan and his colleagues tested this hypothesis on 13-lined ground squirrels in Wisconsin and found that bacteria play a key role in helping them stay strong while they hibernate.

These ground squirrels are an “extreme example of hibernation,” Regan says. They are inactive for six months, during which time their metabolism is reduced by 99 per cent. When they wake up in mid-April, the squirrels “start eating furiously” and double their weight by the fall, he says.

Like humans, ground squirrels have many different kinds of bacteria in their gut, and one group of microbes is doing them an important service. While the squirrels hibernate, urea, the main component in urine, is transported to their intestines where microbes break it down, releasing nitrogen, Regan explains. Nitrogen is essential for making protein, and this process allows the squirrels to preserve and build muscle through the winter.

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There is already interest in how this process could help humans prevent muscle-wasting—whether they’re patients on bed rest or astronauts in zero-gravity environments. Regan has received funding from the Canadian Space Agency to study the possible applications for space travel. However, the human gut microbiome is complex and delicate, and disruptions could have negative impacts, he says. So, careful research must be done before applying this mechanism in space.

For now, this process is best left to the squirrels. While it may be tempting to leave food out to help the little hibernators fatten up, Regan says it’s safer to “let them do what they’re evolved to do.”

Quiz: how much do you know about hibernation?