Do you happen to know much about Honduran fruit bats? I'm having a hard time finding info on them since they're so tough to come across, and when I do it seems to always be a different bat mistaken for one because of white fur. I'm especially perplexed by their faces, they're built like they're meant to echolocate, even though they EXCLUSIVELY eat fruit, yet STILL only hunt for food at night?. They're very weird little guys
Honduran white bats are members of the bat family Phyllostomatidae, the New World leaf-nosed bats- which you can tell by the leaf-shape on their nose. And you’re right, they do echolocate.
In fact, many fruit-eating bats still need to echolocate, because even though they may not need to use it to hunt (though some fruit-eaters may still nab a bug when they spot one) they still need to navigate through the darkness.
Why would a fruit-eater only come out at night? Well, for many reasons. There’s less competition at night, for starters- most primates and birds have gone to sleep. This means there are also fewer flying predators like hawks. It’s also cooler at night, which can prevent a flying mammal that’s working its metabolism to the limit from overheating.
Many plant species accommodate nocturnal customers by adding things like leaves or flowers that reflect sound in a certain way when fruit, nectar, or pollen is available. They also put out stronger smells that lure in the bats. (One species of pitcher plant uses sound reflection to invite insectivorous bats to come poop in it.) So being diurnal is in now way a prerequisite if you want to eat fruit- I myself enjoy a good late night banana.
I would bet that the white-furred bats people keep mistaking for Honduran white bats are Northern ghost bats, which belong to a totally different family. Easiest way to tell them apart is that ghost bats have no leaf on their nose and instead look like grumpy little goblins.
Maybe people also mistake yellow-winged bats for them (again, from a completely different family) or desert long-eared bats or even ghost false vampire bats, but I think the differences there are more obvious unless you’re really unfamiliar with bats in general.
Also, if you see a bat that looks like this… it’s not a real bat, it’s a pin made by CreturFetur on Etsy. Absolutely adorable, but baffling that it keeps being used as though it’s a photo of the real thing.
Im always nervous about bat ring membrane. Its so stretchy. Does it not rip?
No need to be nervous! Bat wing membrane is much stronger than human-made materials like rubber or plastic; the closest equivalent would probably be silicone. (AKA, the stuff used to make the wings for Bat Bot!) But unlike silicone, bats also have the ability to make their wing membranes stiffer or more flexible using rows of unanchored muscles beneath the skin. So if they happen to run into an obstacle, they can adjust it instantly.
Furthermore, bats have an incredible healing ability when it comes to their wings. They can heal almost any hole or tear, given enough time. Small puncture wounds are actually quite common, but the bats can still fly just fine as long as they’re not TOO big. Broken or fractured bones are much more likely to ground a bat than holes in the wing membrane, as a matter of fact.
Below you can see a western yellow bat with a large number of healed scars on its wing- this is more than you’d usually find, but it shows just how resilient they are!
Thank you for writing such a fascinating piece on sapient bats, and bats in general. The part about a single large pup in each bat litter raises a question in regards to the red bat, where sources mention that each litter consists of 2-4 pups! I have seen close-up pictures of a mom with three pups, and have read an account of an exhausted, grounded mother with five! Presumably she is still capable of flight (up to certain age) but can she really fly with 4 pups, never mind 5?
Yes indeedy- red bats and other members of the genus Lasiurus actually normally have two pups instead of one, and have four nipples instead of two. Ironically, they’re also a largely solitary group of bats as well, which means no other females can help raise the pups... it’s a lot!
I can tell you that yes, I’ve seen a red bat mother flying with a pup under each wing, and there are definitely cases of them having 3-4 (or even 5) pups, but 2 is the most common number. These bats are extraordinarily strong fliers- they’re one of the few species that can take off from the ground with a really aggressive pushup- but it’s still incredible that they can hunt successfully while carrying two or more squirmy gremlins!
Unfortunately when the number of pups gets higher than three, it’s unlikely that all of them will make it; that’s a whole lot for Mom to manage. The fact that they do get grounded with all their pups clinging to them just shows you how determined they are to try, though.
She is... doing her best...
(Also here’s a video of a hoary bat, another Lasiurus species, giving birth to twins.)
Hey Koryos, so birds spend a shitton of time messing with and caring for their wings, right? Do bats do anything similar? Or does the lack of feathers let them treat their wings basically just like arms? (I know they can tear the membrane but I'm thinking more abt every day maintenance.)
Good question! For flighted birds, feathers require special maintenance via preening, where they use their beak to put oil from a gland in their backs (uropygial gland) over each feather. This keeps the feathers flexible and waterproof, as well as keeping them clean.
By contrast, for bats the flight surface is composed of (usually) bare skin. Skin is a lot better at maintenancing itself than filaments like feathers or hair, if you consider our own low-maintenance bare skin. However, the bats I worked with did spend hours each day cleaning the surface of their wings, probably to keep the skin soft and flexible. Also probably, in the case of the males especially, to stink themselves up from their scent glands.
Dear Koryos: Can you imagine a universe wherein bats have become the ancestors of some kind of Highly Intelligent Life Form (not necessarily humanlike intelligence, but something as different from today-bats as humans are different from Ancient Primate Ancestor)? I originally just was thinking about what kind of Cultural Norms such beings would have, but then I realized I couldn't really imagine anything except bat-shaped things that more or less thought like humans.
I’ve sat on this question a while because it’s such an interesting one to me. The biggest issue here is that you’d have to specify which bats you’re making your theoretical ancient ancestor, because there’s such a vast diversity of behavior within the group. A vampire bat would be different from a sac-winged bat would be different from a hoary bat would be different from a flying fox ancestor, is what I’m saying. Any social or behavioral organization paradigm that you can think of, there’s a bat that has it.
So to think about what a sapient bat would look like, we first need to assess the intelligence and behavior of possible ancestral bats. And here I’m gonna stick a readmore, because this gets looooong.
Assessing which species would make a good sapience ancestor based on intelligence is also tricky, in large part because bat intelligence remains mostly under-examined. Bats as a whole share the rough reproductive hallmarks of other intelligent mammals and birds, in that they have long lifespans and small litter sizes (in most cases, a single pup). They also have unusually high whole brain size and EQs for their body size, though this is often attributed to the fact that they need more brain matter to handle echolocation.
However, if you look at EQs across Chiroptera, the general trend is that vampire bats and flying foxes tend to have the largest, followed by bulldog bats, false vampire bats, the fruit and nectar eating bats of Phyllostomidae, followed by most other Yinpterochiropteran groups, and then finally the remainder of the insectivorous bats. The authors of the particular paper I’m referencing suggest that this has to do with lifestyle- bats that specialize on blood, fruit, or non-insect prey may require more intelligence to solve the unique problems posed by their food sources compared to insect-eating bats. But the authors do admit that insect-eating bats may also have been constrained by the need to keep their brains smaller and lighter to allow for faster flight, and it’s entirely possible they’re doing more with less. (Also, it’s important to remember that EQ is an imperfect method for assessing intelligence anyway.)
More than one insectivorous bat species is known to have vocal learning and the capacity to imitate, and it’s highly likely that many others do, given the complexity of bat vocal repertoires. Fruit bats, particularly the Egyptian fruit bat, also display vocal imitation. This is considered pretty smart stuff, and among animals only humans, birds, cetaceans (dolphins and whales), pinnipeds (seals), and elephants are known to be regular vocal imitators, putting the bats in a pretty high-class group. Some researchers are now arguing that bats are better candidates for studying the development of human language than birds are, given their closer relationship to us and various other similarities between our vocalizations. There’s even some emerging evidence that some species of bats may recognize each other by vocal signals unique to each individual (in other words, names). In spite of all this, bat vocalizations remain largely understudied, but it’s clear all their chatter serves a purpose.
I bring up all these points because I like reminding people how smart and cool bats are because it emphasizes that intelligence matters in different ways to each bat group, but all of them show the potential for vocal complexity that could approach that of a human’s. So wherever our theoretical sapient bat comes from, it’s likely to be noisy. (Though maybe at frequencies we can’t hear.) Now, if we look at other measures of intelligence such as tool use and environment manipulation, the evidence is more on the side of fruit-eating bats, specifically flying foxes. Though I’ve never seen one use a tool per se, they are perfectly capable solving complex problems using object manipulation. For example, pulling a plastic chain up link by link to get fruit attached to the end involves a similar amount of intelligence as the animals in that famous raven-gets-meat-on-a-string study. They’re also capable of figuring out grenade feeders (feeders in which “pins” have to be removed to make the food drop out) and sometimes will carry around small objects for no apparent reason.
The unusually long thumbs of flying foxes allow them to manipulate objects with surprising precision and they may also use their feet and even wingtips to this end. Object manipulation is part of their natural repertoire (for example, pulling a branch closer to get at something tasty). This separates them somewhat from non-frugivorous bats, who don’t usually need to manipulate objects in pursuit of food- blood-drinking bats just gotta find a spot to bite, carnivorous and piscivorous bats swoop down like hawks, and the most manipulation I’ve seen an insect-eater do is use their tail membrane as a scoop to toss a bug into their mouth. If you want a sapient bat with lots of tool use, fruit-eaters are your likely ancestral group.
However, bats can alter their environment and get better access to food in quite intelligent ways without using objects. Here we ought to look at vampire bats. The white-winged vamipre bat, which feeds primarily on the blood of birds, has co-opted the behavior of domestic chickens in at least two ways. Some bats may perch on the exact spot on a hen’s back that causes her to assume the lordosis posture (i.e., the bout-to-get-boned posture) and feed from the back of her comb with her holding completely still. Others will press up against her brood patch, imitating a particularly goblin-faced little chick, causing her to nestle down on it as the vampire has its meal. This is incredible stuff, as these tactics couldn’t be utilized against their traditional avian prey- meaning the bats have learned how to manipulate chickens all on their own!
Common vampire bats prefer hoofed mammals to birds, and given the larger size of their prey usually don’t have to resort to such nefarious tactics to stay unnoticed. But their creativity also shines when their normal (at this point, human-introduced) prey isn’t available, and they proceed to feed on whatever they can find- which might include sea lions, rats, crocodiles, porcupines, turtles, and even venomous snakes. Each of these critters requires a different strategy on the bat’s part, but apparently the bats tackle the situation with ease. Indeed, one account tells of a vampire bat taunting a rat snake, easily avoiding each strike, until the snake was too exhausted to do anything as the bat brazenly sipped blood from its nose. It should be noted that this particular snake species specializes on feeding on bats.
So in comparison to a sapient fruit bat, a sapient vampire bat might be much more focused on manipulating the behavior of other species, perhaps even domesticating animals for its own use. I should mention, however, that one species of vampire bat- the hairy-legged vampire bat- has evolved a kind of opposable thumb on its foot (a sixth digit fashioned from the calcar), not found in any other bat species. It uses this thumb to help it grip branches as it scuttles around nibbling bird toes, but if you were to make it sapient, you might imagine that instead of the thumb-based object manipulation seen in pteropodids, this fellow would manipulate stuff with its feet. (No relation to the horrible Dougal Dixon futurebats, though, please.)
Speaking of horrible future bats, most of the speculative future bats I’ve seen have two things in common- a) flightlessness and b) a loss of vision in order to rely primarily on echolocation. But neither of these things are really plausible. I’ve discussed why it’s highly unlikely for bats to evolve flightlessness before, so I won’t go into too much detail here, but suffice it to say that unlike birds, which sometimes seem to drop flight as soon as they can get away with it, no bat has evolved to be flightless even when in the most prime conditions. The degree of specialization they have for flight would make it pretty hard to go back to a terrestrial lifestyle, in fact- at best I can imagine a short-flighted bat that flaps from tree to tree.
Some might argue that evolving the brainpower for sapience would necessitate flightlessness because of how heavy and energy-draining such a big brain would be, but just because that’s how humans do it doesn’t mean it HAS to be done that way: look at the brain sizes of highly intelligent birds, such as corvids and parrots- still flying, and quite well. (And the birds that HAVE evolved secondary flightlessness aren’t exactly known for their brainpower). I couldn’t find any information on the neuronal density of bat brains, but I’d bet that it’s higher than expected, given the dizzying amount of calculations that have to take place in an echolocating, flying, insectivorous bat’s head to be successful.
Sightlessness is as unlikely in bats as flightlessness... again, no bat species we know of, living or extinct, has lost its vision! In fact most bats have pretty good vision, despite the reduced size of the eyes of some species. No bat species lives in complete darkness all the time, which would be what would render vision obsolete- vision is still better off than echolocation when it comes to spotting daytime/dawn/dusk/moonlight predators on the move.
Granted, some species have almost lost the ability to see forward due to specialization for echolocation, I’ll give you that...
But they still have quite nice eyes. (And note how slits in the noseleaf allow for a little forward vision.)
In any case if our hypothetical bat evolved from a pteropodid/flying fox it wouldn’t have any echolocation at all, because they don’t echolocate, with the exception of Rousettus species, who do it via tongue-clicking. (And there’s some evidence that other pteropodids have like, a ~mystery~ version of echolocation using their wings, but we hardly know anything about that right now.) Pteropodids are also largely crepuscular- active at dawn/dusk- rather than fully nocturnal, as well, and their primary sense is vision, which accounts for their sometimes inappropriately large eyes.
Speaking large-eyed, fruit eating critters, I can say with confidence that the behavior of large pteropodids I worked with reminded me very much of the macaques I’d once worked with. Even though it’s been debunked that bats and primates are close relatives, I think large flying fox behavior is very similar to cercopitheceine primate behavior (as well as spotted hyena behavior in some ways). Their social organization is a mixed-sex, hierarchical, fission-fusion sort of society, where mating is promiscuous, coalitions can form around power grabs, and competition for spotty resources is quite fierce. Infantacide does occur in fruit bats as in primates, though I’m not sure if there’s been any study on how common it is.
Compare this to the social structure of the common vampire bat, though. Female vampire bats will shift roosts freely and form multiple-matriline groups, usually with a single or two or three males in attendance. These males defend their “harems” from other males, but there’s not much evidence for female policing as in primates, given that females regularly swap roosts; rather, the males seem focused on defending the favorable roosts themselves.
In addition, female vampire bats are pretty famous models of reciprocal altruism, that is, I’ll-scratch-your-back-if-you-scratch-mine behavior. Because they feed entirely on blood, the bats can’t build up any fat reserves, and over 24 hours without feeding can starve them. To combat this, they have a complex network of blood donors (via regurgitation, not vein-piercing) that they turn to in times of need; it’s based on kinship but even more so on how familiar they are with the bat in question, and whether or not they give blood as well when it’s their turn.
Spectral bats are strict carnivores that eat rodents, lizards, birds, and other bats. They’re notable for being a monogamous species, with two parents raising one pup together while defending a hunting territory, and in some cases the offspring of previous years may stick around to help as well, in the manner of canids and some bird species. An even more exceptional monogamous bat is the Dayak fruit bat, where males lactate as well as females. Check out the armpit-nipples of the lactating male, below.
Many other bats have lek breeding systems, like the hammerhead bat, where males congregate together to perform for females, but otherwise the sexes live separately; other species have males that fly completely solo and sing like birds to attract a mate; in other species like the hoary bat both sexes normally live solitary lives.
Most cave-dwelling insectivorous bats stay in sex-segregated groups until it comes time for hibernation, in which case they cluster together in caves, mate, and nap. Social behavior among these species is probably the most poorly understood, given that they are often tucked into near-unreachable places during the day.
Of course, the social behavior in the vast majority of all bat species hasn’t been studied at all, so who knows what other forms their societies might take? I particularly await with eagerness the discovery of a polyandrous bat species similar to tamarins and marmosets... It’s not unfeasible, given the large size of newborn bats (a pup may be up to 1/3 the weight of its mother) and the fact that they often need to be carried rather than hidden, meaning poor mom has gotta carry them while flying, and in some species it can take two years or more before they’re able to survive on their own- as in our small primate cousins, having two dads could really make life easier. I mean... look how big this newborn ghost bat pup is. (And if you’re brave, watch this evening bat giving birth... that looks painful.)
Anyway.
An important indicator of high intelligence would be a great degree of behavioral flexibility (which can lead to transmitted culture) within a species. I don’t think the social behavior of any bat has been studied thoroughly enough to assess how flexible their lifestyles are between groups, but I would bet vampire bats are among some of the most adaptive, as well as some of the most socially receptive and cooperative.
On the other hand I would love to do a study on observational learning in pteropodid bats; I bet they’d do really well. It’s already been shown that they can learn to understand and respond to human pointing gestures.
I guess my ultimate point is, you could expect a sapient bat to behave very differently based on its ancestral lifestyle and morphology (especially whether or not it echolocates) but sapience would imply a degree of behavioral diversity that wouldn’t be limited to any one set of cultural norms. Which is why I hesitate to say any sapient bat would behave just like such-and-such species, but smarter.
It would be very interesting, though, to design a theoretical culture based on creatures that are flighted (travel would be much easier, but energy requirements much higher, how are the flightless elderly cared for?), or one that drinks blood (would certain species’ blood become taboo? what sorts of species might they domesticate and how would they keep them?), one that primarily hangs upside-down in branches (artificial perches would have to go everywhere), or most especially, one that echolocates. I can only imagine the diverse sorts of oral traditions that an echolocating sapient species would have.
Hope this long, long answer gave you at least some degree of what you were looking for! And thanks for the question.
Emballonuridae is a family of bats commonly known as sheath-tailed or sac-winged bats. I’m surprised these bats aren’t better known, because they have very uniquely appealing little faces. I think it’s the perpetually upturned nose.
They also have a stunning variety of colors, from the pure-white northern ghost bat to the dark chocolate of the Hill’s sheath-tailed bat.
Among them are some excellent camoflaugers, such as the proboscis bat, which looks like a bit of lichen or damaged bark on a tree.
In fact, many species in Emballonuridae roost on the trunks and branches of trees, in broad daylight, depending on their camouflage to keep them safe. They like to do it in neat little lines.
Sometimes they also stack.
You may have noticed their short little tailed. They’re sometimes called sheath-tailed bats because these tails protrude out of the membrane between their back legs, which can be pulled up to “sheath” the tail. Here’s a video if you don’t quite understand what I mean.
As I mentioned earlier, they’re also called sac-winged bats. This is because they have special pouches near their wrists designed to release pheromones into the air when they flap their wings. Below is a close up of the pouch, closed and then opened.
For the most part these are very small bats, with weights as low as three to four grams- one of the smallest, the proboscis bat, can get caught in spiderwebs and eaten.
Aside from roosting in trees, these bats roost in caves, crevices, and occasionally, human-made structures like wells or stone tombs. Because of this, several species are known as tomb bats. They’re pretty adorable little harbingers of death if you ask me.
Photo credits:
Main set (species in photo caption): Bat Conservation Intl / Jasmine Vink / University of KwaZulu-Natal / Merlin Tuttle / Michael Penney
Emedded in text: Bateleur Nature Reserve / ARKive / Riley Pearce / PSUNHM / Christian Ziegler
I discussed this in a lot more detail in my article on the pekapeka (a bat from New Zealand that spends about half its time on the ground), but in general, here are the reasons:
1. Compared to other flighted animal groups like birds and insects, bats are relatively new on the scene evolutionarily. They evolved flight about 52 million years ago. Compare that to birds, which have had about 150 million years to get comfortable with flying- only a few have ever lost it in that time.
2. Flying is a powerful antipredator defense and allows bats to get at resources they wouldn’t normally get, like flying insects and high-hanging flowers and fruit. This means there is currently strong evolutionary pressure for bats to retain flight in most parts of the world. One example where there was not was New Zealand (until recently). Even then, the pekapeka and its relatives retained the ability to fly.
3. Compared to birds, bats may simply be too specialized for flight to go back to being completely terrestrial. All living bats have modified hindlimbs and pelvises for flight, because their legs actually make up part of their wings.
It may be difficult to tell from that picture, but a bat’s hind legs are rotated at 90-180 degrees (depending on the species) around from where an ordinary mammal’s would be. In other words, their knees point backwards.
(This is different from a pterosaur, by the way- pterosaurs had wing membranes that attached to their hind limbs as well, but retained forward-pointing knees.)
This makes walking on the ground very difficult for them, and is related to why they roost upside-down. (In fact, some species of bats CAN’T walk on the ground at all!) Even when bats have regained the ability to be good walkers, like the vampire bat has, the style of locomotion is very different from all other living animals, like so:
It’s not a BAD way to get around, but energetically, it’s not as efficient as regular quadrupedal walking.
So, for a bat to “de-specialize” from flight completely might require extreme evolutionary pressures that don’t exist on earth right now. Not that I don’t think they could do it- but a flightless bat would end up looking really, really weird, compared to the mammals we’re used to.
I’ve been trying to re-find this video for FOREVER- check out this footage of a hairy-legged vampire bat drinking blood from the anus of a chicken! (Ignore most of the narration, it’s... not all that accurate.)
Two out of the three species of vampire bats- the white-winged and the hairy-legged- drink blood almost exclusively from birds. The other, the common vampire bat, drinks the blood of large mammals- preferably ungulates. They are big fans of our slow-moving, sedentary livestock.
Vampire bats rarely feed on humans, despite what the narrator claims at the end of the video- this particular species definitely wouldn’t, since it’s a bird specialist. Even the common vampire bat greatly prefers the blood of a pig or cow to that of a human, and most reports of them attacking humans come from places where severe deforestation has wiped out their native prey, and there aren’t livestock around to fill the gap. Even then, it is simple to prevent a bite from a vampire bat: sleep indoors, with the windows shut. Vampires, after all, can’t come in unless invited.
