Bat-shaped cookies on the table. Bat silhouettes in the window. This time of year bats decorate everything from jewelry to pumpkins. Bats have always been associated with Halloween, passed along with other symbols of much older seasonal celebrations.
I clearly recall closely inspecting a dead bat years ago: the contrast between the thin, delicate wing membrane and the dense, incredibly soft fur was remarkable. The wings, stretched out by the four elongated finger bones, connected to the body along the sides and down the frail legs to the small, clawed feet. Continuing the flying surface, the membrane also connected the legs and skinny tail. The thumb, at the wrist (forward bend) of the wing, formed a small claw.
Warm-blooded, furry, giving live birth then nursing the young, bats are clearly mammals. In fact, nearly a quarter of all mammal species world-wide are bats; bats are the only mammals that fly. ("Flying" squirrels glide down from higher perches.)
While bats may look very much alike, nearly a dozen different species of bats have been documented for Coos County. Their ranges can overlap considerably, with more than one species sharing an area but differentiating themselves by what they eat, where they feed (such as in the open vs. among the trees), their flying/foraging techniques, where they roost, or when they emerge from their roosts.
Famously, bats find their way around and locate food with echolocation. After sending out sounds too high for human ears, the bat listens for the timing and quality of the echo to navigate and to pinpoint prey. Some bats channel the sound waves through their mouth, other species through their nose. The image of a bat flying with mouth open is the image of the former: bats usually catch their insect prey by snagging it with a wing tip or the tail.
Like most bats world-wide, all our bats are insectivores. However, a few bats specialize in other foods, including fruit, nectar, frogs, fish, or other animals — even other bats. Three species of vampire bats lap blood that rises to small cuts they make on sleeping mammals or birds. (Vampire bats rarely bite people. Limited to Central and South America, they were named after European myths, not the other way 'round.)
Bats are prey, too: owls and other predators sometimes hang around the openings of bat roosts to snag the winged tidbits as they fly out to forage.
In Western Oregon, most bats live under bark or in crevasses of rocks or trees and snags — and buildings. Some bats migrate in autumn, though most of ours apparently migrate only locally to suitable hibernation sites. Many bats prefer to roost together and may hibernate in very large groups. The bat noises we can hear while they’re roosting, and other times, are social communications.
Besides being one of our most fascinating local inhabitants, bats play important roles in our forests and meadows. As flying mammals, bats live on a very tight energy budget and need to eat about their weight in insects every night. Some of those insects, particularly certain species of moths and beetles, compete or interfere with human activities — such as managing agricultural crops and timber. For example, bats are fond of coddling moths, the parents of many worms found in apples.
Bats are diverse and remarkably adapted. They're agile flyers and admirable hunters, and helpful to people. Why do some of us fear them?
Yes, bats can carry rabies, but at about the same rate as other wild mammals: less than one-half of one percent. (And, understandably, a trapped or cornered bat may bite if handled. Wouldn’t you?) Histoplasmosis, a fungal lung disease in people, may be caused by bird droppings as well as by bat guano.
Perhaps it's an appearance issue? Most bats have vaguely human faces, usually with over-sized ears and beady eyes, and sometimes with outlandish folds and flaps around the nose. They may show their sharp, carnivore teeth. Further, bats hide during our time (day) and come out at night, flitting erratically in the darkness.
But few people get close enough to a bat to see its face or to learn enough about them to dispel false beliefs.
For example, bats are not blind: some can see in the dark better than humans do. And bats do not get caught in people's hair, though they may swoop close while chasing the insects that have been drawn to the people.
With pesticides, habitat destruction, climate change, and more, humans pose a much greater threat to bats than the other way ‘round. Bats in your attic this winter? If you rouse them from hibernation during the winter when there’s no food available, you may force them to use up their entire winter body stores and they could starve before spring.
Coming from an unknown source, the most recent threat to North American bats is “white nose syndrome,” a fatal fungal infection that’s recently spread to the Pacific Northwest. (Please report dying or sick bats here: http://www.dfw.state.or.us/wildlife/health_program/WNS/reporting.asp )
It's appropriate to honor bats in autumn before they hunker down for the winter. They are worthy of year-round affection and appreciation. Flutter on!
For information on how you can arrange an exploration of our fascinating natural history, contact Marty at 541-267-4027, firstname.lastname@example.org, or www.facebook.com/wavecrestdiscoveries. www.wavecrestdiscoveries.com
Questions and comments about local natural history are welcome; gift certificates are available.