It’s dusk at the old schoolhouse. Volunteers are arriving, prepared for a show. Someone puts out homemade cookies and fudge. Others park themselves in lawn chairs.
Suddenly, silently, a myriad of shadows start blanketing the sky.
Hundreds of little brown bats (Myotis lucifugus) have taken flight. In search of an evening meal, they are launching themselves from roosts arrayed around the schoolhouse, which now serves as the North Oyster Community Centre in Ladysmith, B.C.
A clamour of clicking erupts – not from the animals echolocating their prey, but because the eight volunteers are furiously using their tally counters to log each emerging adult, which measure only five to 10 centimetres from head to tail.
Within 20 minutes, the spectacle is over. The final tally of the season is more than 1,600 adults. Ian Fisher and his colleagues pack up quietly. They will put their counters in storage until they return to the site next spring to once again track the species, also known as little brown myotis.
Since 2012, this grassroots surveillance has offered the best window into how these animals are grappling with a variety of modern pressures, including pesticides that kill off vast numbers of their prey. This network of volunteers is also B.C.’s early warning system against white nose syndrome, a disease that is destroying millions of these insectivores further down the West Coast, across the Rockies and all over North America.
Nobody knows how many of these flying mammals live in British Columbia, but this spring and summer, more than a thousand people working with the government-funded Community Bat Programs of BC conducted counts at more than 300 roosts. These counts don’t estimate an overall population of bats in the province because the volunteers’ work can cover only a fraction of the overall roosts of the 15 species known to call the province home. But, the annual bat count found more than 3,000 adults at some of the 274 sites counted in 2023, according to the annual report published in January of this year.
Paula Rodriguez de la Vega first became enthralled by bats when a professor at the University of Calgary brought one into her undergraduate ecology class. Three decades later, Rodriguez de la Vega is provincial co-ordinator for Community Bat Programs, working to protect the animal that acts as vital pest control.
“In Canada they’re so incredibly important because they eat so many nocturnal insects: they eat not only mosquitoes, but they also eat a lot of agricultural pests – a lot of moths and beetles that eat agricultural crops. They also eat a lot of forestry pests,” Ms. Rodriguez de la Vega says in a phone interview from her home in Penticton, B.C.
A new mother little brown bat that is feeding milk to its baby can eat her weight in insects every night, she said.
The final count of the season in Ladysmith revealed that the population in the community centre, like others monitored across the province, has not seen any significant decline. But the volunteers’ work is not over for the year.
As the season turns, bats will leave their summer roosts to seek out deeper, darker crevasses for the winter. Caves and abandoned mines offer the animals the ideal temperature and humidity for hibernacula (rhymes with “Dracula”) – the hiding spots where they sleep until their prey begins reappearing, months later.
During hibernation, volunteers watch for dead bats and, come spring, they collect huge bags of guano. Both are sent to a provincial lab to test for white nose syndrome.
The bats’ relatives in Europe and Asia seem to have developed an immunity to this fungal infection, but North American bats that get infected in winter see 90 to 100 per-cent of the population within their roost decimated, according to Ms. Rodriguez de la Vega.
The fungus interrupts a bat’s hibernation by irritating them, forcing them to shiver for about half an hour to raise their temperature and heart rate so they can wake up and lick the fungus off and move their wings. Over time, this routine burns up their fat stores, leading to them ending their hibernation earlier to seek out insects in the wild.
Unable to find insects out in the elements that early in the year, they perish emaciated and battling the fungus as it grows into their respiratory system.
“It’s a very ugly death of starvation and complications,” she says.
White-nose syndrome was detected in 2021 in a guano sample from Grand Forks, B.C., but the province has otherwise been spared from this calamitous disease. Researchers fear the spread is imminent and can be devastating on bat populations.
“We’ve been monitoring for it and bracing for it,” says Ms. Rodriguez de la Vega.
