The tent-making bat (Uroderma bilobatum ) is an American leaf-nosed bat (Phyllostomidae) found in lowland forests of Central and South America. This medium-sized bat has a gray coat with a pale white stripe running down the middle of the back. Its face is characterized by a fleshy noseleaf and four white stripes. Primarily a frugivore, it may supplement its diet with insects, flower parts, pollen, and nectar. Its common name comes from its curious behavior of constructing tents out of large, fan-shaped leaves. These roosts provide excellent protection from the tropical rains, and a single tent roost may house several bats at once. This bat is quite common in its geographic range; hence, its conservation status is listed as Least Concern.
The genus name Uroderma is said to be derived from the Greek words uro for “tail” and derma for “skin”, thus meaning “tail of skin”. This describes their tail membrane, which is made entirely of skin, lacking tail vertebrae. The proper word for “tail” in ancient Greek is however oura (οὐρά).The species name bilobatum is said to be derived from the Greek and Latin roots bi for “two” and lobat for “lobed” in reference to their first upper incisors, which have two lobes.
Uroderma bilobatum is medium in size, weighing between 13–20 g with a body length of 59–69 mm. Typically, the females are slightly larger than the males. Their pelage ranges in color from dark gray to grayish brown, with their belly slightly lighter in color than their back. The individual hairs of their coat are bicolor, being lighter in color at the base than at the top. A thin, white stripe runs down the middle of the back from behind the head to the rump. The face has two striking symmetrical pairs of white stripes. One pair goes over the head, between and to the back of the ears. The other pair lies just below the eye. This facemask may serve a camouflage purpose by making their eyes less obvious to would-be predators. Their brown noseleaf and ears are rimmed with yellow or white. They have a U-shaped tail membrane that is practically hairless and measures 14–16 mm in length. A dorsal view of their skull reveals a depression between the frontal bone and their snout. Their dental formula is i 2/2, c 1/1, p 2/2, m 3/3, which gives them a total of 32 teeth. They also possess a calcar and a slightly pigmented, permanently open dactylopatagium minus.
During flight, the heart rate of U. bilobatum is about 900 beats per minute. However, they normally only spend 30 minutes per day in flight. This is reduced to an average of 490 beats per minute while resting at night, and declines to an average of 375 beats per minute while resting during the day. Their daytime heart rate is periodically (two to three times per hour for 5 to 7 minutes per episode) lowered further to 200–250 beats per minute as part of an apparent strategy to reduce energy expenditure. Such conservation is important to their survival, as their fat reserves would be used up within 24 hours without food.
These bats are found in Central America from Oaxaca and Veracruz, Mexico to Peru, Bolivia, and southeastern Brazil. They also live on the island of Trinidad. Most specimens have been collected at elevations below 600 m, but some have been found as high as 1500 m above sea level.
Uroderma bilobatum lives in low-elevation evergreen and deciduous forests, second-growth forests, and fruit groves. They are primarily frugivores and have been observed carrying small, unripe figs in their mouths. At times they may supplement their diet with insects, flower parts, or nectar.
Female tent-making bats may reproduce twice in one year. In Panama, pregnant females have been observed in February and in June. In Costa Rica, pregnant females move into coconut groves in July, just at the beginning of the wet season, and exhibit synchrony in parturition. Each litter consists of only one pup, which is born after a gestation period of 4–5 months. The nursing females form maternity colonies of 20–40 individuals in one tent roost. Roosting in groups may have thermoregulation benefits for the pups and lactating mothers. They do not carry their young with them on their nightly foraging flights; however, it appears that they may first move their pups to more protected roosts before beginning to forage. The pups become independent after one month.
