Nov. 11, 2008 by Judy
Bats Need Love (Yours)
Did you know Hawaii has bats? A bat, one species of bat, that is: The Hawaiian Hoary Bat. All summer I've been watching 3-4 bats feed just out over the water at the shoreline in south Maui, but I've watched them feed right off of the canoe club in north Kihei as well, for many years, and I'm always all grins when I detect, usually just after sunset, their circular, flittery, swoopy flights. I'm a bat geek.
I grew up in central Texas near one of the largest colonies of Mexican free-tail bats known. On warm summer evenings I would go lay in the back yard, facing up, and the warmth of my body would attract mosquitos. Mosquito bites pretty much do nothing to me, I'm one of those people, so the mosquito thing for me was a bonus because the bats would zip in within inches of my body to feast on them. Wave after wave of acrobatic little mammal furballs would course through the dimming light of day, kind of like the large molecules of a big river, and I would lay there in the 'river' and try to hear their wing beats. I could never hear their high echo-location squeaks or see their sweet little squashed faces, but I loved laying there in the gathering dark, feeling a part of some great ritual. I doubt the bats got anything so esoteric out of the deal - they were just really hungry.
Fast-forward to college, and a friend of mine invited me up to see the bat colony he was working with up on the 10th floor of a huge research facility. The colony was hanging from the ceiling of a big fenced enclosure in the middle of a large room, and in the center of the enclosure was a table with a tray running the length of it. The tray was for bugs, at feeding time. We opened the fenced gate and walked in, which elicited a ripple of nervous disturbance in the sleepy members of the colony overhead. "Watch this," my friend said, and he clapped once. The entire colony dropped as one, whirled around us in a sudden hurricane of brown warmth, and within seconds was attached back up to the ceiling. And probably really annoyed at being shocked awake like that. Still, I could have done that 100 times. After all those years of laying in the back yard hoping for something astonishing, I had finally managed to spend a few seconds in the heart of an entire flying colony, right in the center, beating heart. Smitten me. I nearly became a bat biologist, nearly.
But I digress. Here in Hawaii we are on the other side of an incredibly effective bottleneck - the Pacific Ocean. Not much that flies or floats gets over, through or under it. The odds of making it here, in the years before humans showed up and started carting this and that here and there, were slim, so very slim. Organisms that did make it here (I always imagine them as bedraggled, exhausted, and near delirium or death, but that's because I have a dramatic streak) had to bang out a niche for themselves and then survive. Which means that both sexes needed to show up, and the right food/conditions needed to be in place, and nobody got eaten before they could go about the business of reproducing. The odds were formidable, all the way around.
For that reason, we have only two mammals naturally occurring here. They are not the mongoose and rat, the cat and dog, the goat and cow, or the wallaby (Oahu). They are the Hawaiian Monk Seal and the Hawaiian Hoary Bat. And before you go getting all uncomfortable, 'hoary' means 'tipped with frost', the ends of the brownish or grayish hairs of the pelt being white.
Hawaiian ecologists believe that our bat made it, somehow, against all odds, maybe in the arms of a hurricane, to land here long before we humans showed up a couple of thousand years ago. The island of Moloka'i does have a fossil record of another, smaller bat, but Lasiurus cinereus semotus is the only bat we have now. It's an endemic (found here and only here) subspecies of an American (all three parts of America) native bat. Native Hawaiians call it `Ope`ape`a, because its wings kinda look like a half taro leaf or a Polynesian sail.
It's a small light-brownish/reddish bat, weighs only a few ounces, and it's solitary. Males and females get together to mate about once a year, but it's not like my childhood experience of voluminous batness. Those populous colonies of Mexican Free-tails are the sorts of population dynamics people tend to think of, when they think of bat social life, but our bats are lonely little sweethearts, roosting alone in a tree or a rock face for most of the day and then working his or her way down toward the shoreline, or a big open field, as evening falls. They manage to make quite a dent in the flying insect population on their foraging flights, often eating as much as their own weight over the course of the night. I would like you to imagine eating your own weight in pasta and cheeseburgers or Thai food or M-n-M's, or whatever, in a night. And then doing it again the next night. Amazing, no?
Like many mammals, the females are a tad larger than the males - though neither gender has wings much more than 10 to 14 inches wide when stretched all the way out. Females are larger, in case you are suddenly wondering about this, because they have the work of kid-bearing, feeding, and rearing to do. That means they need to have a little more meat on their bones for the coming energy commitment of momhood. Females are pregnant a little less than two months and give birth while hanging upside down - and usually have one or two pups...but CAN have 4. Yikes. The newborns only weigh about 5 grams so they're probably the cutest damn things ever, all tucked in there inside mom's wing. The pup's eyes don't open for almost 2 weeks, and at about a month they try out the flying thing.
All of the main Hawaiian islands have bats to some degree except Oahu, which developed too far into the roosting areas. This is an officially listed endangered species, and has been since 1970. No one is really sure how many are on each island, but sightings are frequent enough to keep ecologists hopeful. Here are some insanely cute photos from the Honolulu Zoo: honoluluzoo.org
And here's a great little passage about their bat Ehu:
We learned much from Ehu over 5 years, such as documenting a change in her coat color pattern from a generalized reddish-brown to the classic hoary pattern. It also appears that she showed a consistent body weight gain during the winter months (based on daily body weight measurements). Although we have only been exposed to two individual Hawaiian bats, the combined 8 years of experience with them shows them to be very docile and gentle creatures. They would literally fall asleep in your palm after feeding and with gentle stroking of their heads.
Federally funded research of the Hawaiian bat continues on the Big Island of Hawaii yet there is still much unknown about this enigmatic but increasingly charismatic native Hawaiian mammal. We will always be grateful for every opportunity to be exposed to these remarkable animals.
Note: The above comments are by our Zoo Veterinarian, Dr. Ben Okimoto.
One hopeful bit of news about our only flying land mammal is that it seems to be fairly adaptable, resting and roosting in non-native trees (like Cook pines) as well as the native trees (like Koa), or even in abandoned buildings. It seems non-specific in terms of the insects it feeds on, so it is eating some of the mistakes we've added to the ecosystem in the last few years as well as the flying food it's always known. Their current diet includes everything from mosquitos (introduced to Hawaii by whaling vessels in the early 1800's) to native moths. I'm sure they'll give everything a try at least once, sort of like the rest of us at a salad bar. I've seen them at sea level many times, and conservationist friends and colleagues have seen them over the summit of Haleakala (10,023 ft. above sea level). That means they've got good range and they're putting up with us fairly well at the moment, but it's no reason to make things harder for them. The best thing you can do is appreciate them for what they are, make a point of trying to see them at sunset so you can say you've seen Hawaii's only native flying land mammal, and help spread the news that they're to be appreciated for the work they do, not slandered. They're working as hard as they can to just be. I'm sure you can relate.