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Nectar Bats

(click on a photo to enlarge)

They arrived around mid-August. I know that because the hummingbird feeders were strangely empty one morning when I knew they were nearly full the evening before. There were two different species and they came in numbers.

Nectar Bats at Hummingbird Feeder

There are two types of bats in Arizona — insectivorous (insect eaters) and nectarivorous (nectar/pollen eaters). The nectarivorous Mexican Long-tongued Bats (Choeronycteris mexicana) and Lesser Long-nosed Bats (Leptonycteris curasoae yerbabuenae) fly up from Mexico following the blooming of certain plants with flowers adapted for bat pollination. With diets largely of nectar and protein-rich pollen, these long-tongued bats are very effective pollinators benefiting not only themselves but the plants they visit as well. Members of the Leaf-nosed Bat family, both species have a fleshy protuberance on their noses.

Lesser Long-nosed Bat showing fleshy protuberance on nose

The bats began visiting the feeders in mid-August and most have migrated through by the end of September. The Lesser Long-nosed Bat is federally listed as endangered, and the Mexican Long-tongued Bat is listed as threatened so we were happy to provide a supplement to their food supply while they make their way back to Mexico for the winter. However, when you have close to a hundred hummingbirds sipping nectar by day and large bats by night, you’d better have plenty of sugar on hand and plan on replenishing all feeders daily!

Difficult to view, the dark, swooping bodies that fly in and out under the patio roof make very fleeting stops at the feeders yet are able to empty them overnight. In fact, they mostly feed on the wing because their feet are adapted to hanging upside down so perching is not really an option for them. While I could see bats visiting the feeders I really couldn’t make out any details, so I set up my camera and flash on a tripod at an open window in the complete darkness. At the hint of any movement around the feeder I pressed a remote shutter release. I got some pretty amazing shots of the two species in action. The first thing I noticed was their very large wingspan. The feeder bottles are quart-size to give you some perspective on the size of the bat.

The Lesser Long-nosed Bat arrives in Southeast Arizona in April. The females, already pregnant, bear their young in maternity colonies which congregate in caves or old mines. They feed mainly on the flowers of Saguaro Cacti but will also eat Saguaro fruits. Males arrive several months later. They have small ears, large eyes and shorter snouts than Mexican Long-tongued Bats. Their fur also tends to be brownish in color. The membrane on their legs is deeply cut giving the appearance of wearing a pair of pants.

Lesser Long-nosed bat showing deeply cut leg membrane

Both bat species have long tongues which allow them to reach deeply into large or tubular flowers for pollen and nectar. Those long tongues also allow them to utilize hummingbird feeders. Note the pollen on this bat’s head and the residual pollen on the feeder perch.

Lesser Long-nosed Bat

The Mexican Long-tongued Bat is slightly smaller with a longer snout than the Lesser Long-nosed. The membrane between the legs is not so deeply incised and has been described as a “skirt.” This is a helpful distinction between the two species. Their preferred nectar and pollen source is Agave flowers. Note the very long tongue shown in this photo.

Mexican Long-tongued Bat

They’re also pretty adept at finding nectar droplets that are running down the side of the feeder. Who says bats are blind? Looks like they have excellent eyesight to me!

Mexican Long-tongued Bat

So today, September 29, we are down to a dozen or so hummingbirds and a handful of nectar bats. The cooler nights and shorter days, no doubt, have signaled that greener pastures, better food and warmer weather are farther south. It’s time to move on.

Published by Arlene Ripley on September 29th, 2009 Tagged Arizona, Cochise County, Mammals, Nature

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