One creature that almost always gets a bad rap is the bat – from sucking your blood and potentially turning you into a vampire to perhaps being responsible for our latest global pandemic – this little creature gets enough criticism to drive one batty.
In fact, there are lots of references to the bat in our vocabulary – you can be “blind as a bat” (they aren’t blind), “batting 1000” – having a good result, maybe you “went to bat” for someone, or maybe you left a scene in a hurry- like a “bat out of hell”. (Right off the “bat”, I knew this could be endless), but I don’t want to act like an old “bat” so I’m hoping readers won’t “bat an eyelash” at this small diversion from the original intent of this article to share some information about bats – my intent is not to drive you “batty!”.
Let’s move on and start with dispelling some of the myths about bats – they are not blind, and will not become entangled in your hair (if a bat swoops close to you he is probably after the bugs attracted to the heat from your head), less than 1 out of 20,000 bats have rabies and no bats in Washington State dine on blood.
Bats are immune to many diseases that are lethal to humans like Ebola, SARS and Nipah. Unfortunately this makes them natural reservoirs for these diseases. Most disease spillover from bats, however, is human caused. The SARS outbreak in China was caused by humans touching the dead carcasses of bats sold in wet markets. It is possible that our current outbreak of Covid came from a Chinese wet market – I think the jury is still out on that at this time but in all cases, live bats are not transmitting the disease – humans handling dead bats are.
Actually the benefits of bats far outweigh any problems that may incur with them. A female nursing little brown bat may consume her body weight in insects in one night during the summer. Bats help the rainforests – in some African, Asian and European forests bats are responsible for over 50% of the vegetation, spreading seeds through their guano (poop) and pollinating while seeking nectar. Malaria-carrying mosquitoes are responsible for approximately 750,000 human deaths a year – one type of bat is capable of eating 1200 mosquitoes in a single hour!
There are more than 1100 species of bats worldwide, 15 of these species live in Washington State. One of the largest bat species in Washington is referred to as the (not very original) “big brown bat” (Eptesicus fuscus). The Big Brown bat can weigh up to 26 grams with a wing span up to 13 inches and can fly up to 40 mph. Big brown bats range from southern and central Canada to northern South America and the Caribbean – mostly preferring forest land but also found on range land and in urban settings. Insects are the main meal for most members of the bat species – the big brown bat has large, muscular jaws and heavy teeth allowing them to crunch beetles – their preferred snack- but they are also known to eat moths, termites, leafhoppers, flies and flying ants, depending on availability in the region. Big Brown bats are one of the most cold tolerant bats – and one of the last to go into hibernation. Big Brown bats are commonly found near human structures – you may find one in your attic, under a shutter, or in some other cranny in hibernation. Bats hold the honor of being the only flying mammal.
Another bat frequently seen in our area is the common little brown bat (what did you expect?). Myotis lucifus, commonly referred to as the “little brown bat” is a mere 2.5 inches in length. Little brown bats feed mostly two to three hours after dusk – when insects are most active. They hunt at the edge of forests or on or near water. Most prey is captured in the air and consumed in flight.
As we all experience cold winter months, the bat is no exception. There aren’t many insects flying around in freezing temperatures and bats must either migrate- which some do – or hibernate. A Hibernaculum is a term for any type of shelter used by plants or animals in a dormant state. Caves for bears, burrows for squirrels and snakes, mine shafts, old wells and tree hollows are some examples. A bat’s normal body temperature is 100 degrees – the hibernaculum temperatures must be cool enough to allow a low body temperature but not freeze and humid enough to keep the bats from dehydrating. The bats heart rate is reduced to one beat every four or five seconds thus allowing a bat to survive on a few grams of stored fat for the five to six month hibernation period. Bats hibernate alone or in groups in late September or October. It’s important not to disturb hibernating bats as they can quickly use up their stored fat if aroused and if they are disturbed multiple times, hibernating bats may actually starve to death before spring.
Most of the breeding takes place in late fall or winter at the hibernation site. Interestingly enough, the female bat stores the sperm until the following spring when females rouse from hibernation. Gestation is 60 days and a normal litter of one or two pups is born in the spring. Female bats and their offspring live in nursing colonies. Pups cannot fly for 30 days and spend much of their time suckling, Mom leaves them in the nursery while she goes out to hunt. The largest known maternity roost of little brown bats in Washington contains about 1,000 adults and roost together with 2000 Yuma Myotis (another bat species) under an abandoned railroad trestle near Olympia. The male bats roost alone or in small groups – leaving the prime, warm quarters for the nursing moms. Female bats may return to the nursery they were born in year after year. Little brown bats commonly live six to seven years, however one 31 year old was found in the wild. Big brown bats’ lifespan is 8-20 years.
In reality we have little to fear from bats – but from their perspective things are kind of scary. Bats have been experiencing a worldwide epidemic of White Nose Syndrome – a disease that has killed millions of bats – affecting mostly the hibernating species. There is no cure at this time and scientists around the world are working to study this disease. Mortality rates from this disease is up to 90% in some colonies. Over 100 confirmed cases have been found to date in Washington bats. If you find sick or dead bats, groups of bats, or notice bats acting strangely, such as flying outside during the day in winter or spring, please report your sighting online at https://wdfw.wa.gov/bats or call WDFW at 360-902-2515. Even though the fungus is primarily spread from bat-to-bat contact, humans can unintentionally spread it as well. People can carry fungal spores on clothing, shoes, or recreation equipment that touches the fungus.
Bats are also seriously affected by loss of habitat as humans inhabit more real estate. Wildlife agencies realize the importance of these habitats and encourage installations of bat boxes in national forests and other wildlife areas. Lots of regular people encourage bats to live near them by providing a safe habitat including a bat box. (Instructions to build this simple box can easily be found on the internet). Pesticides also contribute to the dwindling bat population.
No matter where you live, there are most likely bats living nearby. There are many more species of bats you can learn about – this article just touches on a few. Learning more about our local wildlife helps us understand their needs and requirements – and hopefully allows us all to live together in this wilderness community that we all call home. Visit my favorite, reliable source, Washington’s Department of Fish & Wildlife’s website for information on all of our local wildlife.
National bat week begins October 24th and runs through Halloween. What a great time (and season) to learn more about our bat neighbors.