Wednesday, October 27, 2010

Adirondack Bats: Lasiurus Borealis, The Redhead

red-batWhen most people think of bats, they either think of caves, or their attics. While a good number of species are colonial and hang out together in caves (in winter) or attics/barns/bridges (warmer months), we do have three species here in the Adirondacks that live solo lives in the woods. These are the red, hoary and silver-haired bats. Not only is their lifestyle not what we expect, but they also look much different from what we expect, for these are the most colorful bats in our part of batdom.

Today we will contemplate the red bat (Lasiurus borealis). Like any true redhead, the red bat is actually more of an orangish color, sometimes leaning more toward the yellow end of the spectrum. The males are more brightly colored than the females, which makes sense when one considers the rather exposed lifestyle this bat leads (a female can more easily hide with her young if her coloration is dull, kind of like birds).

The red bat is a medium-sized bat with a wingspan of about 11.5 to 13.25 inches. As the species name suggests, this is a bat found up north almost as far as the tree line in Canada. It is also found throughout the eastern US (from the Dakotas southward to Texas, and all points easterly). In the winter, it heads southward, spending the majority spending its time in the Gulf states. Those who hang out where the winter temperatures still drop below freezing (like the Ohio River Valley) enter a state of hibernation, just like their northern cousins that stay in the caves around the Park.

Like many a snowbird, red bats are found in the Adirondacks in the summer. During the daylight hours, they dangle upside down in the foliage of hardwood forests, clinging with one foot to a leaf petiole, twig or branch. Because of their cryptic coloration, they blend in. A sleeping red bat, if you find one, is bound to look like no more than a dead leaf. The roost of choice of a red bat provides protection from above and the sides, while remaining open below for a quick escape. There has no perches below upon which a predatory bird might lurk, it is protected from the wind, and the ground beneath the roost site is dark enough to prevent the sun from casting a reflection upwards that might expose the sleeping bat to prying eyes.

Red bats head out in the early evening to feed in open areas and along forest edges, each bat claiming a particular territory that it forages every night, often not far from its roost. Like other insectivorous bats, red bats use echolocation pulses to locate and target prey species. While leaf- and planthoppers, beetles, moths and such make up a large part of the diet, when tent caterpillars are abundant, red bats feast heavily on these forest pests. Red bats, therefore, are a valuable part of our forest ecosystem.

One of the things that make red bats stand out from their other chiropteran brethren (or, rather, sisteren), is their fecundity. The majority of bats have one litter a year, and that litter consists most often of one, or sometimes two, young. Red bats, however, quite often have three, or even four, offspring per litter.
During the day, the mother bat hangs out in the tree with her young, each baby clinging to her with its wings while simultaneously hanging on to the tree with one foot. At night, she leaves her charges hanging in the tree while she goes out to forage for food.

Female bats with young to nurse have to find upwards of four times as much food as they would if they were without young. Producing milk for a hungry brood is an energy drain for any mammal, and bats have the added drain of having to fly after their food. Insects, while highly nutritious, don’t pack on a lot of meat (although some moths can be quite filling). Mother bats work terribly hard to get enough food for themselves and their young, and red bats even more so, for they have two to four times as many mouths to feed than other insectivorous bats.

One of the strategies a red bat uses to help find food is to home in on the feeding buzzes of other red bats in the area. All’s fair in love, war and feeding. If you are out in the early evening and see a pair of bats seemingly chasing each other along the forest edge, it might just be that you are witnessing a pair of red bats vying for the same insect snack. These episodes of food stealing don’t seem to be viewed as aggressive take-overs, since the bats remain in the same territory afterwards, both continuing to hunt and feed.

I have always hoped to see a red bat, but so far this animal has eluded me. I’m in good company, though, for red bats, like the other solitary tree dwellers, are seldomly seen by anyone. Still, if you happen to be walking in the woods in the summer, glance up from time to time into the leaves of the trees you pass. Look for a russet-colored leaf hanging among the green ones. If you are lucky, you just might find a red bat. If you do, take a photo and send it to me – I’d love to see it, too.

Photo Credit: Merlin Tuttle, Bat Conservation International

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Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.

2 Responses

  1. Ellen Rathbone says:

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