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With spring on its way, scientists and conservationists who monitor bats are keeping a close eye out for the animals — especially dead ones outdoors, or bats that have left hibernation early.

Both are signs that the ­animals might have White Nose Syndrome, a fungal disease responsible for the death of ­millions of bats in eastern North America.

Bats infected with the Pseudogymnoascus destructans fungus exhibit a white, fuzzy fungal growth on their faces or wings, which gives the disease its common name. The fungus thrives in the same cold, damp places where bats hibernate.

The fungus kills the bats indirectly, by causing infected bats to wake early from their hibernation. Without their seasonal food sources, they dehydrate, starve and eventually die.

The disease has a near 100 per cent mortality rate for some bat species; it doesn’t affect humans. It has pushed some species to the brink of extinction and has been blamed for the deaths of more than six million bats since it was first discovered in eastern North America in 2006. It affects 13 bat species in Europe.

For researchers, it’s not a matter of if, but when White Nose Syndrome shows up on Vancouver Island.

The disease has been ­confirmed in King County in Washington state, approximately 150 kilometres south of the Canadian border.

In Canada, the most western distribution of the disease is along the border between ­Saskatchewan and Manitoba.

Detection of the fungus in B.C. is challenging because bats here hibernate singly or in small groups, which means that identifying and tracking the spread of the disease relies heavily on public assistance, bat experts say.

That’s why the Habitat Acquisition Trust and the provincial government have launched the Southern Vancouver Island Community Bat Program, a citizen-scientist program to monitor bat activity.

“We need more eyes on the ground,” said Mandy Kellner, provincial co-ordinator with the B.C. Community Bat Program. “Outdoor enthusiasts and homeowners with roosts on their property may be the first to find evidence of trouble.”

The public is encouraged to report dead bats or any sightings of winter bat activity to the program, said Kellner, adding bat carcasses will be submitted for testing for White Nose Syndrome.

Not every winter bat sighting signals trouble — healthy bats sometimes wake up to drink or even eat, if insects are active, but those sightings should be reported.

Citizen scientists are advised to leave sleeping bats found hibernating by themselves in a woodpile or basement entryway alone, although they can be photographed and reported to the bat program. (If you must move a bat, visit bcbats.ca for advice, and remember to never touch a bat with bare hands.)

The Little Brown Bat (Myotis lucifugus) is the most common of nine species of bats found in the capital region.

Although there is an annual bat count undertaken by citizen scientists, there is no official estimate of their population.

“Their small size and weight — some bat species can weigh as little as a paper clip — makes banding them like birds unworkable,” said Ronna Woudstra, bat program co-ordinator for the Habitat Acquisition Trust.

Woudstra said researchers at Simon Fraser University are planning to install radio towers that will be able to detect the sonar waves the bats emit when flying. “That potentially will help us track their movements and discover where they are roosting — and count them.”

British Columbia has the most diverse community of bat species in the country, more than any other province. Of the 19 species of bats native to Canada, 16 reside throughout the province. Unfortunately, more than half are also considered to be a species at risk, with the Little Brown Bat on the endangered list.

If you garden or spend time outdoors at night, you will appreciate having bats around, as they eat more insects than any other nighttime predator. A bat can consume 10 mosquitoes a minute, or 600 an hour.

No bats in Canada eat fruit or blood. Even their droppings, known as guano, make an excellent fertilizer.

Scientists are working on treatments for White Nose Syndrome using biological or non-chemical agents, while other research is looking at slowing fungal growth by changing the temperature or humidity in hibernation areas.

Until a cure is found, scientists believe that mitigation strategies, such as the preservation and restoration of bat habitats, will give the bat population the best chance at rebounding.

The public is encouraged to report — but never touch — any dead bats on the ground. There is always a risk of rabies should you or your pet have direct contact with a dead bat.

If you come across a dead bat, contact the Southern Vancouver Island Community Bat Program at 1-855-922-2287 ext 24 or info@bcbats.ca. For more information, go to bcbats.ca.

parrais@timescolonist.com