They only come out at night
Discover the wonder of bats with your family this Halloween
Caught up in the ever-increasing frenzy of Halloween, we are once again decorating our homes and front yards with the traditional symbols of the season: witches, spiders, ghosts, jack o’lanterns and, of course, bats. Although this is all done in good fun, it doesn’t do much to improve this enigmatic mammal's image.
This week, I'd like to dispel a few myths about bats and explore what fascinating - but highly threatened creatures they are. First, bats are not blind. In fact, they can see as well or better than humans can. Nor are they attracted to people's hair or carry more disease than other wild animals. Although rabies does occur in slightly less than one percent of the bat population, this is much lower than in foxes and skunks. Because bats are both shy and nocturnal, most people only see them up close when they make an unexpected appearance in your house. Clearly, not the best of circumstances!
Bats are actually gentle, highly intelligent mammals with the cutest of faces. Some have the facial expression of a fawn or rabbit. Their fur is soft and silky, thanks to the inordinate amount of time spent grooming. Some species are also altruistic and share meals with other members of the colony. Like humans, they also keep track of which individuals do the sharing. Scientists have observed that those bats that shared in the past are offered food by others in the future - and vice versa. Bats are also human-like in having a long lifespan. Some can live 40 years.
The way they rear their young is also endearing. Females form a maternity colony each spring, which bring together sisters, nieces, aunts and grandmothers. These moms may have known each other for decades. As with humans, most species only have one baby per year, and the mothers feed their baby from a pair of breasts.
Unlike humans, however, bats have evolved the ability to hibernate, which allows them to survive on a greatly reduced heart rate, body temperature and metabolism. A bat’s heart rate, for example, typically drops from 600 beats per minute to only 10 to 80 beats. In this way, precious body fat burns slowly enough to last the entire winter.
Bats, of course, are prodigious insect eaters and use echolocation to find their prey. The time and directional difference between the original sound projected by the bat and the subsequent echo contains the information needed to locate and identify objects, be it a wall or a moth. The sounds bats produce are ultrasonic and beyond the range of human hearing. A bat detector, however, will convert these signals to audible frequencies and let humans know if bats are present.
The evolution of bats is still unclear. They represent the only known example of flight in mammals. And, no, they are not mice that somehow evolved the ability to fly; in fact, bats are not even remotely related to rodents. Bats are such unique mammals that they've been given their own group, “Chiroptera”, which means hand-wing. How flying evolved, or from which ancestor, is clouded in mystery due to a lack of fossilized evidence. The 'missing link' between non-flying mammals and bats has yet to be discovered. Without this important piece of the puzzle, it's impossible to really understand their lineage. Some scientists think that fruit-eating bats - a different group within Chiroptera - may actually have evolved from the primates. This hypothesis suggests that humans and fruit bats share a recent common ancestor.
Ontario bats
We have eight species of bats in Ontario, all of which have been found in the Kawarthas. They range in size from fairly large (15 centimetres) to quite small (10 centimetres). Of these, the red, hoary and silverhaired bats are migratory, although we don't know exactly where they go in the winter. These species are less gregarious and roost in trees rather than congregating in caves and mineshafts.
The other five species hibernate from October to March, mostly in caves and abandoned mines, which provide stable temperatures above freezing as well as high humidity. They are the big brown bat, tricolored bat, little brown myotis bat, northern long-eared myotis and eastern small-footed myotis. With the exception of the big brown, all of these species are susceptible to White Nose Syndrome (WNS), which I discuss below.
Until WNS struck, the little brown myotis bat was our most abundant species. Small and glossy brown, these bats belong to the hard-to-identify Myotis complex. They often select attics, abandoned buildings and barns for summer colonies where they can raise their young. For years, there was a colony in the tower of Keene United Church.
Now, however, the big brown is the most commonly seen species. They are medium in size and found both in wooded habitats near water and in urban areas. Big brown bats are a hardy species, arriving late at hibernation sites. I have seen big browns as late as November, feasting on the moths of Indian Summer. Their greater hardiness also allows these bats to overwinter in the unheated attics and walls of buildings or near the entrance to a cave or mine.
White Nose Syndrome
Bat populations are experiencing disastrous declines. This is due to a fungus that is killing the animals as they attempt to overwinter in caves and abandoned mines. White Nose Syndrome was first documented in New York State in the winter of 2006– 2007.
The most obvious symptom is the presence of a white fuzz on the bat's nose. This is caused by a fungus (Pseudogymnoascus destructans or Pd), which probably originated in Europe and was transported here by humans. The fungus infects the skin on the muzzle, ears and wings and causes legions, which result in water loss. This, in turn, disrupts hibernation. The bats get itchy and thirsty, start waking up too often and burn precious fat reserves. Consequently, they are unable to make it through to spring.
WNS is now spreading westward and, as of this past summer, has been observed in 33 states and seven provinces. Most of western Canada and the US will soon be affected. The disease is fatal in about 95 per cent of cases and has already killed an estimated 6.7 million bats. It is considered the worst wildlife disease outbreak ever in North America. It threatens to drive some species extinct. Fortunately, the Pd fungus grows only in the cold and is not harmful to humans or to any other species.
Hope on the horizon?
Still, there may be hope for the future of bats. According to Dr. Christina Davy of the Species at Risk research team in the Ontario Ministry of Natural Resources and Forestry, five percent of bats never develop the symptoms of WNS are therefore able to survive. In fact, all five species still overwinter in abandoned mines in the Bancroft area, albeit in drastically reduced numbers. She and her team are now trying to find out what's different about these individuals. Is it a superior ability to store fat? Do they come out of hibernation earlier or go in later? Do they have a stronger immune response? And, maybe most importantly, are they doing well enough to eventually spur the recovery of the entire population?
At a public talk last month at Ferris Provincial Park, Dr. Davy described some of the research underway to answer these questions and, in doing so, better inform conservation efforts. Passive integrated transponder (PIT) tags have been put on 19,000 bats that hibernate in caves in Manitoba. The electronic tag is dormant until activated by a reader, which scans the animal and reveals its unique code number. This permits a tagged individual to be distinguished from every other one. The process is analogous to scanning barcodes in a grocery store. By also taking DNA samples, the researchers hope to find out if particular genetic profiles are linked to a bat’s chance of surviving WNS.
How to help bats
The best way to help bats is by supporting breeding colonies. If you must rid a building of bats, never evict them during the spring and early summer when the females are rearing pups. Any bat exclusion should be done in August with a oneway exit. The openings can then be sealed in September.
If you find a bat in your house, open the windows, turn out the lights, and allow the animal to let itself out. Should you need to pick one up, put on heavy gloves. Alternatively, sweep the animal into a dustpan or small container. If you find a bat in your house in winter, contact the new Kawartha Wildlife Centre at 705-8684340.
You should also consider putting up a bat box. Place it on a sunny, south-facing wall, but never in a tree or near a branch where predators could raid it. These boxes will sometimes be used as a maternity site.
Even if your box remains empty, it is still a great conversation starter on the importance of bat conservation. Bats provide enormous ecosystem services and are extremely important in controlling insects. Most importantly, however, they are fascinating animals and make the natural world even more intriguing. Share the wonder of bats with your kids this Halloween! Local Climate Change News
September temperatures in the Kawarthas were 2.4 C warmer than the 1971-2000 average. Fully half of the months so far this year have been 2.4 or more degrees warmer than normal. Keep in mind that the latest IPCC report warned that we must limit planet-wide warming to 1.5 C to avoid devastating impacts.