Do bats scare you? Though they frighten a lot of people, we’re rather fond of them here in the Bruce Museum Science Department. We’ve written other bat-themed Storage Two posts, admired bats as they flew overhead, and just this Wednesday, had the honor of meeting one of our local bat residents in person. We spotted this little red bat on the loading dock and immediately had to stop and admire her.
Bats aren’t too interested in museum displays. Usually when a bat is seen out and about during the day it is a sign that the bat is ill or injured. The previous night was one of our first frosts of the season, and we suspect this bat may have been cold-shocked and dazed. She recovered enough to fly away after warming herself in the morning sun, and we sure she’s still out there patrolling our Greenwich skies. In honor of our furry visitor and with Halloween fast approaching, it seems like time to write about bats again. In July, I talked about how vampire bats are one of the most altruistic animal species ever discovered. This quality is certainly admirable, but it isn’t the only reason we should appreciate our winged neighbors.
Bats as Pest Control
Almost every animal has its defender, but you’d have a hard time finding someone who has good things to say about mosquitoes. When it comes to these blood-sucking menaces, the less the better, right? Bats agree with you. There are over 1,000 bat species and about 70% of those eat an all-insect diet. A single bat can eat 600-1000 mosquitoes an hour! With bat colonies numbering in the thousands, or sometimes millions, their insect population control abilities are incredible. More than just mosquitoes, they also eat many insects that do damage to crops. Because of bats, we can live a less itchy life and use far fewer insecticides.
Bats as Pollinators
Of the bats that don’t eat insects, some eat nectar. They visit night-blooming flowers to slurp the sugar-rich nectar. As they do, pollen coats their furry faces. They bring this pollen to the next flower they visit, facilitating genetic exchange and fertilization. This is good for the plants but also for us. Without bats, we wouldn’t have some of our favorite foods. Tequila would be one of the casualties of a bat-free world. The drink is made from Agave plants, which are pollinated exclusively by bats. A lot of tropical fruits are pollinated by bats too, like bananas, mangoes, guavas, and even chocolate.
Bats as Gardeners
Bats don’t go out weeding with a shovel and a hoe, but their role as gardeners is an important one. Some bats eat insects, some eat nectar, but some eat fruit. When a bat chows down on a tasty fruit, it often accidentally consumes seeds. Many seeds are protected by hard outer coats that prevent digestion. They pass through the bat’s digestive tract unharmed and are excreted whole. This is called seed dispersal.
Seed dispersal is vital to a well-functioning ecosystem. If seeds fall too close to the parent tree they become forced into competition, making it much harder to thrive. Bats fly all over the place during their foraging, dropping seeds as they go. When bats excrete seeds, they’re doing more than just providing transportation. Guano is excellent fertilizer, giving a boost to initial growing stages. Bat guano can be commercially purchased for gardening, but these seeds get it for free.
In places where heavy deforestation has taken place, bat-facilitated seed dispersal becomes even more vital. They can fly between isolated forest fragments, spreading seeds along the way. In Central South American forests the importance of bats is even clearer. There, logging has depleted woodlands and hunting has caused sharp declines in numbers of large animals, like deer and macaw. It has been thought that the loss of so many large animals would mean trouble for plants with large seeds that depend on those animals for dispersal. Fortunately, bats are taking up the job. Large seeds have been found under the nests of tentmaker bats. Even big-seeded plants benefit with bats around.
Whether they’re pollinating their flowers, dispersing their seeds, or eating their pests, plants have a lot to be grateful for where bats are concerned!
Bats are beneficial for humans and the environment, but they have a lot of other fascinating, strange, and even charming traits. One particularly charismatic bat species is the Honduran white bat. Breaking away from bat stereotypes, these bats don’t live in caves. Tent-making bats like the Honduran white bat make their own homes out of the massive leaves of Heliconia plants. They carefully chew through the veins that support a spread leaf. This causes the sides to droop downwards, forming a sheltered tent-like structure. The little bats then roost within, sheltered from rain and predators and camouflaged by the green light filtering onto their white fur.
Bad News for Bats (And Some Good News Too)
Bats have had a hard time over the past few years. White-nose syndrome (WNS) is a disease affecting American bats and is responsible for the death of over 6 million bats thus far. When bats hibernate in massive colonies over the winter it provides the perfect opportunity for WNS to spread. Colonies can lose as many as 90% of their members to the white fuzzy fungus coating their muzzles and wings. Connecticut is one of the states affected by WNS and has seen massive mortality rates.
Given the huge role that bats play in keeping insect populations under control, WNS is very concerning. It’s been estimated that the insectivorous habits of bats save farmers about $4 billion per year on pest control. Now, costs and the use of pesticides are starting to rise again. It’s a dire situation, one that leaves scientists wondering if we might be on the verge of a drastic reordering of North American ecology. Fortunately, not all news is bad where WNS is concerned.
A common soil bacteria, Rhodococcus rhodochrous appears to be the Achilles heel of the white-nose fungus. The bacteria release compounds that prevent fungus growth, slowing or sometimes even stopping the spread of WNS. Infected bats inoculated with the bacteria are able to recover in a laboratory setting, and scientists are working on applying the cure on a wider scale. The Nature Conservancy has constructed artificial cave in Tennessee to test this cure and others in preparation for bringing treatments to bat hibernacula all over the country.
Want to support your local bats? Here are a few things you can do:
1. Share this blog or other educational materials with your friends and family. Let them know that bats aren’t scary; they’re some of our best allies in the natural world.
2. Reduce pesticide use. By killing insects, we’re also killing the main food source for many bats. Skip the pesticides and feed a bat!
3. Protect bat habitat. Bats love to roost in dead and dying trees. If you have one on your property that doesn’t pose any hazards, consider keeping it up and giving bats a place to stay.
4. Put up a bat house. Even if you don’t have dead trees, you can make or buy your own bat house to entice bats to your property. People have been putting up bat houses as a form of natural pest control since the early 1900s. Hate mosquitoes? Invite some bats to your home!
5. Participate in citizen science projects, such as helping to identify bat calls.
6. Don’t bother bats. If a bat is awoken from its winter hibernation it may become prematurely active and starve after it depletes its fat reserves. Stay out of caves and mines where you think bats might be hibernating.
8. Learn how to avoid contributing to the spread of WNS, and help ensure the health and safety of our bats for years to come.
The scariest thing about bats isn’t their fanged faces; it’s what life might be like without them. With the hard work of conservators, scientists, and citizens, we can all make sure that doesn’t happen.
- Kate Dzikiewicz, Paul Griswold Howes Fellow