With their nocturnal habits and behaviour that largely keeps them away from humans, bats can sometimes stay out of sight and out of mind.
Even so, nighttime in the Pembina Valley can be punctuated by the whirr of wings and high-pitched squeaks of an animal that is very helpful in tackling the populations of pesky insects.
However, the keen eye and ear may have noticed that their presence has been more infrequent in recent years.
According to Dr. Craig Willis, a biology professor and the graduate program chair in biology at the University of Winnipeg whose work includes bat conservation, the quieter nights can be explained by the disease that has been significantly harming small mammals for almost two decades now.
“Bats are a group of animals that are in trouble everywhere for a lot of different reasons. In Canada, though, we've got a couple of big issues that are affecting their populations,” he says.
“We spend most of our efforts and work studying species affected by a disease called White-nose Syndrome, which has killed millions of hibernating bats in North America.”
What is White-nose syndrome?
The disease, which is fungal and thrives in cold environments, infects bats with a white fungus that has catastrophic effects on their health.
According to enviroliteracy.org, the presence of the fungus “disrupts the bats’ hibernation cycle, leading to a cascade of detrimental effects such as dehydration, starvation, and ultimately, death.”
New York State, 2007
While not all the questions about how White-nose Syndrome (WNS) came to affect bat populations in North America so severely have been answered, it’s clear where it started on the continent.
“Basically, in northern New York State in 2007, New York State biologists went in to do their annual winter counts of bats. They would go into these caves and mines where there are hundreds of thousands of bats hibernating historically, and they would take photographs of everybody in the cave, so then they count noses later and we get an idea of population trend,” says Dr. Willis.
“Instead of finding bats all snuggling and cuddling on the ceilings and walls of those caves, they found carpets of dead bats on the floor and a few stragglers kind of hanging on, covered in this white stuff.”
Dr. Willis says that since the shocking discovery, the disease has “marched all the way across the continent.”
“It’s not quite everywhere in North America yet, but it's certainly in most of the continent. It's jumped across the Rockies now, and so it's spread incredibly quickly,” he says.
“Environmental economists in the US did a study where they compared counties where this disease had killed a whole lot of bats to similar counties where bats hadn't died yet. What they found was that there was an increase in crop damage in those places that led in the next year to farmers using more pesticides on their crops.”
-Dr. Craig Willis on the potential impact of decreased bat populations.
Researchers at the University of Winnipeg, including Dr. Willis himself, did some of the first work to discover that the fungus originated in Europe and Asia.
“It turns out there's white stuff growing on bats all over Europe and Asia, it's just not killing them,” he says. “It’s now clear that our fungus was introduced to North America from somewhere in Eurasia. It's all the way across the continent there, and it's pretty clear that the bats have co-evolved with the fungus over tens of thousands, maybe hundreds of thousands of years, so they've evolved resistance to it. Our Bats have not.”
Dr. Willis says that WNS has caused North America to lose “big numbers” of bats.
He says his team monitors colonies in Boissevain and Cartwright that have taken a hit.
“These are little brown bat colonies, and we've seen [this situation] in lots of places in Manitoba where, on average, our numbers are down by about 80% for little brown bats, which was formerly our most common species in some places,” he says.
“Elsewhere in North America, 6-7 years after the initial population crash, people are seeing the populations start to rebound. We're at about the six-year mark, and we're not really seeing a lot of evidence of that rebound yet, so we're sort of crossing our fingers and hoping that in the next couple of years, we start to see these populations recover.”
Why should we care about the bats?
For Dr. Willis, although bats can be a nuisance to some if they take up residence in an unwanted location or perhaps a bit “creepy” to others due to their elusive nature, what is happening with bats should be a concern to everyone.
One reason is related to crops.
“We don't have a good handle on this in Manitoba, and for most of Canada, but we know from studies in the US and even in the northern US that bats are incredibly important controllers of crop pests,” he says.
“I think sort of the most compelling reason as a nature nerd myself is that they're just an incredibly cool and interesting and unusual part of nature that's valuable in their own right.”
-Dr. Craig Willis on why bats matter.
“The most compelling evidence for this comes from our bat disease .... Environmental economists in the US did a study where they compared counties where this disease had killed a whole lot of bats to similar counties where bats hadn't died yet. What they found was that there was an increase in crop damage in those places that led, in the next year, to farmers using more pesticides on their crops.
“That costs farmers money. It costs people money at the grocery store, and there are more pests because the bats aren't eating the insects. What was even more alarming is that increased pesticide use in those counties was associated with an increase in human infant mortality, presumably because some of that pesticide drifts and exposes people to more pesticide chemicals.”
Dr. Willis says the experiment cannot conclude cause and effect, but it was a “rigorous study” that suggests that without bats, humans are “not only going to have to spend more money, but also going to potentially face some human health consequences.”
Adding to the diversity of Manitoba
Beyond the potentially helpful contribution bats provide to humans, they are also unique creatures that add to the diversity of life in Manitoba.
For Dr. Willis, that’s worth caring about, too.
“I think sort of the most compelling reason, as a nature nerd myself, is that they're just an incredibly cool and interesting and unusual part of nature that's valuable in their own right,” he says.
“Bats are the only mammals that can fly under their own power, and that ability has allowed them to spread out all over the world. There are about 1500 species of bats around the world. About one in five of every mammal species is a bat, so they're an incredible proportion of all the mammals out there.”
“We’ve tried hard. I think we were a little naive at the start in thinking that maybe we could solve this disease.”
-Dr. Craig Willis on White-nose Syndrome.
Dr. Willis adds that bat diversity is “incredible,” and their biology is “just weird.”
“I've taken a photograph of a 20-year-old [little brown] bat that someone had marked with a band 20 years before I encountered it and took a photo, so we know that species can live over 40 years in the wild. These are incredible animals in terms of their biology. They're just off the scale for lifespan.”
Bats are also unique in that they have very low reproductive rates — they only have one or two pups a year, in contrast to a mouse, which can have 10, 20, or even 30 offspring a year, according to Dr. Willis.
“I like to think of them as sort of miniature flying grizzly bears because they have these big territories, long lifespans, and low reproductive rates,” he says.
Is there a cure for WNS?
Although researchers are attempting to address WNS for the sake of bat species that add to the province’s landscape in many ways, finding a cure has proven challenging.
“We’ve tried hard. I think we were a little naive at the start in thinking that maybe we could solve this disease. A lot of people spent a lot of effort testing out things that we might be able to spray on bats that don't hurt the bats and don't hurt all the other thousands and millions of microbes that live in the same environment,” says Dr. Willis, adding that some things seem to slow down the fungus, but there isn’t a cure so far.
The professor says that because of this, habitat is the area of focus for his team.
“We know some bats survive the winter with the disease, and those survivors are incredibly precious because they almost certainly have inherited traits that help them make it through the winter that they can pass on to their offspring,” he says.
“We're trying to help bats evolve resistance to this disease by protecting the habitats they need to recover in the spring and produce pups in the summer.”
Dr. Willis says that these habitats tend to be old forests close to wetlands.
How can the public help?
While the situation for bats is quite dire, there is still some hope.
According to Dr. Willis, helping conserve forests and wetlands is key for the public interested in protecting bats and supporting their recovery.
“This is something we can do to help them,” he says. “[We can] leave those kinds of habitats intact.”
He says the public can also help by protecting colonies of bats in attics and barns by removing them through the proper channels.
Dr. Willis also encourages the community to do their part by reporting bat colony sightings at Batwatch, a site that collects valuable data provided by individuals who feel the call to help protect nature.