Nomads of the New World Tropics
by Diana Clarke
Animal Adaptation
Wild animals must adapt to their natural environment. For instance, arboreal animals employ a variety of superbly designed bodily structures to aid them in climbing and traversing trees and other surfaces. Sloths hang on to branches with their recurved claws. Flying squirrels and lemurs have folding membranes (patagiums) between their limbs to assist them in gliding from tree to tree.
Bats, too, have patagiums—the leading edge of their wings--in addition to powerful flight muscles, skeletal modifications and aerodynamically structured wing membranes to generate lift and propulsion and to facilitate other flight maneuvers. They are the only mammals that can fly.
Furthermore, bats generally hang upside down by their hind limbs. However, one bat that roosts in an upright position has concave, circular adhesive pads on its limbs to aid it in climbing and in clinging to various surfaces.
A Disk-winged Bat
The Spix New World Disk-winged Bat, aka New World Sucker-footed Bat (Thyropteridae Tricolor) of Central and South America is an insectivorous microbat (microchiroptera). This little reddish-brown bat weighs about 4 grams (0.1 ounces). Its head and body measure 34-52 mm (1.3-2.0 in.), its tail, 25-33 mm (1.0-1.3 in.); and its forearm, 27-38 mm (1.1-1.5 in.). Unlike the fruit-eating megabat (megachiroptera), the Spix bat uses echolocation (sonar) to hunt for its prey, consuming up to 0.8 grams each night, which is about 20% of its weight. The female bat has been known to take its offspring along for the evening flight in search of food. And incredible as it may sound, the offspring can weigh up to 46% of its mother’s weight.
Digital Pads
Other animals, such as the snail and gecko, can adhere to surfaces, but the Spix New World Disk-winged bat, one of four disk-winged bats, is the only mammal that contains digital pads.
The sucker-footed bat licks its suction cups, not unlike a child who wets an arrow, so it will stick better to a smooth surface. These 3.5 to 3.9-mm (0.1 in.) in diameter adhesive discs, which can support the Spix bat’s own weight, also produce a gluey secretion to aid adhesion.
The Spix Bat's Temporary Home
The Spix bat may inhabit agricultural vegetation, such as the inner, smooth surface of a tubular-shaped banana or heliconia plant at the precise stage of the plant’s development. When the plant reaches a maximum height, it begins to unfurl. Some varieties of plants grow as high as 3 meters or 9.8 ft. before unfurling. A 50 to 100-mm (2-4 in.) diameter opening is adequate to accommodate a group of two to eleven bats, including juveniles. Yet, the plant is a temporary home, for the leaves will open too wide within one to two days.
Because the heliconia and banana plants are able to grow large and thrive in the sunny, warm and moist tropical climate, the plants are able to provide a safe haven from rain, sunlight and predators for the bats that hang from a single leaf until the group has to move again.
References
Animal Diversity Web
University of Michigan
1995-2002
Belize Biodiversity Information System
Version 1.5
December, 2001
Wildlife Conservation Society
Summary of Species Account for Belize
Neotropical Bat Information System
Walker’s Mammals of the World 5.1.
Nowak, Ronald M. 1997
John Hopkins University Press.
Fenton, M. Brock. 2001. Bats. Checkmark Books, New York.
Fenton, M. Brock. 1992. Bats. Facts on File, New York.
Hill, John E. and Smith, James D. 1984. Bats: A Natural History. University of Texas Press, Austin.
Kunz, Thomas H., ed. 1982. Ecology of Bats. Plenum Publishing Corporation, New York.
Nowak, Ronald M. and Paradiso, John L. 1983. Walker's Mammals of the World, Vol. 2. The John Hopkins University Press, Baltimore.
Novick, Alvin. 1969. The World of Bats. Holt, Rinehart and Winston, New York.
Schober, Wilfried. 1984. The Lives of Bats. Arco Publishing, Inc., New York.
Voelker, William. 1986. The Natural History of Living Mammals. Plexus Publishing, Inc., Medford.
Wilson, Don E. 1997. Bats in Question: the Smithsonian Answer Book. Smithsonian Institution., Washington.
Photo Credit: Carolyn M. Miller, Associate Conservation Zoologist
Wildlife Conservation Society
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Last modified: 10/26/03
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