THERE ARE OVER 1,300 DIFFERENT BAT SPECIES, MEANING BATS MAKE UP ONE-FIFTH OF ALL MAMMAL SPECIES

to groom themselves and remove the fungal growth, but this has lethal consequences, as bats must carefully ration their energy during hibernation to survive without eating until the spring. Starving and disoriented, some will fly outside in mid-winter in a search for food, a suicidal mission in most of Canada.

The fungus arrived from Europe and crossed the Atlantic Ocean, brought by humans. It first appeared in North America in 2006 in a popular tourist attraction in upstate New York called Howe Caverns, where, it is speculated, foreign cavers carrying fungal spores on their clothing and gear introduced the disease to local bat populations. Once the disease was established on the continent, the main form of transmission became bat to bat, and that has been a major factor in its rapid spread. Bats don’t always roost close to their hibernation sites: some fly hundreds of kilometres; others are inadvertent long-distance hitchhikers on trains, trucks and boats.

The fungus seems to kill only hibernating bats and so is a serious threat to more than half of the continent’s 47 bat species that hibernate over winter. The hardest hit species are little brown bats, northern long-eared bats and tri-coloured bats, all of which have suffered massive die-offs. In February 2012, the trio were given an emergency assessment by the Committee on the Status of Endangered Wildlife in Canada and recommended for listing as endangered species. Some provinces acted quickly, including Ontario, which moved to protect these species within three months. It took more than two years for the federal government to follow suit.