Nature Notes: Benefits of Bats
Bats are one of the most fascinating, yet misunderstood creatures in our culture. Perceptions of bats have largely been forged from European lore, associating bast with witches and vampires. They’ve been portrayed as evil creatures of the night, representing symbols of death, trickery, and the underworld in many stories, books, TV shows, and more. Due to their nocturnal behavior and rare encounters with people, bats remain shrouded in mystery. Let’s take a look at misconceptions before diving deeper into bats.
Common Bat Misconceptions:
Bats are birds. No, bats are mammals – the only mammal capable of true flight!
Bats are flying mice. No, bats are not rodents at all. In fact, they’re more closely related to primates (and us!) than rodents.
Bats are blind. No, bats are not blind. Many bats have reduced vision and use echolocation to find food, but they’re not blind. Many fruit-eating bats have large eyes and rely on their vision to find food!
Bats dirty, ugly, and scary. Well, the ugly and scary thing is more of an opinion, but bats are definitely not dirty! Like cats, they spend a lot of time grooming themselves and keeping their fur clean! Personally, I think bats are adorable! Check out these fruit bat pups!
All bats carry rabies. Like all mammals, bats can carry rabies. However, scientists estimate that 0.5% of bats carry rabies. Annually 0-2 people die from bat rabies a year in the United States. It is very rare! Most bites from bats occur when humans try handling or helping an injured/sick bat on the ground or in their house. You should always wear thick gloves while handling bats! Globally, over 30,000 people per year die from rabies and 99% of cases are caused by dogs. Thankfully, due to vaccination programs, this is rare in the United States.
All bats suck blood. No, but some of them do! Only 3 of 1,200+ species of bats rely on blood as a food source. All 3 types of vampire bats live in Central and South America and humans are NOT their preferred meal. These bats mostly feed on livestock, which may not even notice.
Bats caused the current coronavirus pandemic. Scientists do not yet know for sure where the virus originated. After studying the genome of the virus, they were able to tell that it shares 96% genetic make up with a similar virus that has been found in bats. To be clear, we share 96% of the same genetic make up with Chimpanzees – but we’re very different. So don’t jump to conclusions. Scientists do think it likely has origins tracing back to bats, but there may have been an intermediary species other than bats to help it jump to humans or it could have mutated once it was spreading in humans to become more harmful. Ultimately, even if it did come from a bat, it’s not their fault! Humans are encroaching more and more into bat habitats, plus people are hunting, poaching, eating, and selling bats at open markets, putting us at risk for diseases they carry. More research is needed and is currently being done. In the meantime, this YouTube video sheds some light on why bats carry so many viruses that can negatively impact humans.
Bats are Fascinating!
There are over 1,200 species of bats found on every continent except Antarctica. Remarkably, they make up 20% of mammalian species, yet little money is invested in bat research and conservation. The greatest bat diversity can be found near the equator. Here in the US, we have 43 species of bats with 7 living in Minnesota and 8 in Wisconsin. Bats come in many sizes, ranging from the tiny Bumblebee Bat from Thailand (less than 1.5” in length, 6” wingspan, and weighs as much as a penny) to the enormous Giant Golden Flying Fox in the Philippines (with a wingspan of up to nearly 6 feet and weighing in at well over 2 pounds)!
Bat bodies are a true example of form follows function. Bats are the only mammals capable of true flight. Their arm and hand bones are surprisingly similar to ours, except their fingers are elongated giving structure to their wings. The wing membrane is an extension of the skin, called the patagium, and is remarkably tough, flexible, and fast-healing. Some bats also have a webbed tail, which they can use as a flight break, to change direction, and to help scoop food towards their mouth mid-flight! Flight is an extremely energy intense process, and as a result, proportional to their size, bats have one of the most powerful hearts in the animal kingdom. During flight, a bat’s heart beats over 1,000 times per minute (300 bpm while resting and only 4 bpm while hibernating)! Their hearts are designed with unique valves that reduce blood flow to their wings during hibernation (to conserve energy) and to their heads while hanging upside down (to prevent blood from pooling in their heads, like it would for us)! Speaking of hanging upside down, the hind limbs of bats are rotated 180 degrees (knees bending backwards) and they have specialized tendons in their feet that require them to flex to let go of their roost, preventing falls while snoozing. They have large claws to help their grip while hanging. Bats are certainly well adapted for their lifestyle!
Bats are Beneficial!
Bats are extremely beneficial, providing billions of dollars a year in ecosystem services. There are two main types of bats, microchiroptera and megachiroptera, each providing different services.
Microchiroptera (microbats) tend to be smaller, have small eyes and large ears used for echolocation, and mostly eat insects, though some have a wide range of diets including frogs, scorpions, mice, etc. Many microbats have odd-looking facial adaptations to help them with echolocation: face ridges, ear ”bonnets,” huge rabbit ears, and even mohawks! But these adaptations make them formidable predators of insects, many of which are considered pests. It’s estimated a Little Brown Bat can eat between 600-1,200 mosquitoes PER HOUR and a colony of Big Brown Bats can consume over 1.3 billion pest insects per year!! One study estimated bats are worth $22.9 billion dollars a year in costs saved from reduced pesticide applications, and perhaps up to $53 billion a year, in the United States alone! Not to mention the guano from large colonies of microbats is an effective and profitable fertilizer!
Megachiroptera (megabats) tend to be larger in size, have big eyes and small ears, have big muzzles and (adorable) fox-like faces, and eat only fruit or nectar. These bats rely more on their vision, which is adapted for low-light environments, then on echolocation. Many megabats also have a fantastic sense of smell, leading them to their preferred fruits and nectar. This means bats play a pivotal role as pollinators and seed dispersers, especially since their flight capabilities allow them to travel long distances in a night. Some flowers, like those of the economically and ecologically important Baobab tree in West Africa, have large flowers that only open at night and hang down below the branches, making it difficult for other species to access the nectar and pollinate the flowers. Without bats, who serve as the primary pollinators, an extinction chain of many plants and animals beginning with the Baobab could occur.
Bats that eat fruit are also doing an incredibly important ecosystem service! On average, a fruit bat eats 2-3x its weight in fruit each night. Due to their high energy demands and fast metabolism, they digest food extremely quickly – in as little as 15 minutes! Seeds often pass through without being digested. The result? Huge amounts of seeds dispersed in their waste as they fly between feeding sites! A study which put out tarps in open, abandoned fields noticed few seeds collected there during the day, but night brought a “seed rain” as bats flew overhead, dispersing seeds into the fields. Once the early colonizing plants from bat dispersal take root, it brings other avian and mammalian seed dispersers to the habitat, eventually reforesting the area.
From eating pests, to pollinating and dispersing seeds, many of our favorite products are from bat-dependent plants: bananas, peaches, mangoes, figs, Kapok (used in life preservers), agave, saguaro cacti, dates, vanilla, Brazil nuts, avocados, almonds, cashews, chocolate, gum, tequila, beauty products, and so much more!
Bats are in Trouble!
Bat populations across the globe are declining. Twenty-four species of bats are critically endangered, 53 species are endangered, and over 100 other species are considered vulnerable. There is not enough data on many more species to know if their population is at risk. Bats face dangers from misunderstanding (intentionally killed due to fear), loss of habitat, hunting and poaching, hibernation disruption, disturbance in maternal caves, wind energy, and disease. White-nosed Syndrome (WNS) is an emerging disease of hibernating bats, first recorded in New England in 2007-2008. Named for a white fungus that infects skin on a bat’s muzzle, ears, and wings, this fungus causes bats to display abnormal behaviors, such as increased movement and flight during hibernation, which burns up their winter energy reserves resulting in starvation. WNS is spreading rapidly across the United States and is decimating bat populations, sometimes causing 90-100% mortality in bat colonies.
These population threats are compounded because bats don’t follow the typical rule of smaller-sized mammals having high reproduction rates. For their size, bats are the slowest reproducing mammals on earth and the longest lived. They typically give birth to one pup at a time, once per year. (That pup is 25% of it’s mom’s weight – the equivalent of a 150lb woman giving birth to a 38lb baby! Woah!) Slow reproduction rates can hamper a bat population’s ability to come back after a decline.
You Can Help Bats!
You can help to educate family, friends, neighbors, and community members about the importance of bats and address the misconceptions. Reduce the fear in our communities about bats! Make sure you’re following the “look but don’t touch” rules when encountering bats. If you have to handle a bat in your home, make sure you are wearing gloves! Build a bat house or a bat roost to provide bats a safe shelter and to reduce the number of bats finding their way into human buildings. Leave dead trees on your property if it is safe as they’re a great natural roost! Join a bat-friendly organization, like BatCon, Merlin Tuttle’s Bat Conservation, or Bat World. Get involved in a citizen science project aimed at helping to monitor bat populations, like the Wisconsin Bat Program. There are many different actions you can do to help bats – pick one that is right for you!