(Noctilionidae)
Class: Mammalia
Order: Chiroptera
Suborder: Microchiroptera
Family: Noctilionidae
Thumbnail description
Noctilionids get their common name from their distinctive full and pendant lips and cheek pouches, which makes them look much like a bulldog; their legs are long and their feet and claws are large; give off a pungent, fishy odor
Size
Large bats ranging 2.1–3.6 in (54–92 mm) in forearm length and weighing 0.6–7.8 oz (18–78 g)
Number of genera, species
1 genus; 2 species
Habitat
Tropical lowland areas near water
Conservation status
Overall not threatened, though regional populations may be at risk
Distribution
Neotropical
Evolution and systematics
The systematic affinities of the family Noctilionidae were debated for many years. Recent analyses of large molecular and morphological datasets provide strong evidence that these bats are closely allied with the other exclusively neotropical bat families, Mormoopidae and Phyllostomidae, and with the endemic New Zealand family, Mystacinidae, that together form the superfamily Noctilionoidea.
Analyses of molecular variation among populations of the two noctilionid species and their close relatives, the mormoopids, suggest that the evolution of a fish-eating lifestyle in Noctilio leporinus is relatively recent, within three million years. These data also suggest the possibility that Noctilio albiventris is actually composed of two, distinct lineages that diverged from each other approximately one to three million years ago. Additional data are needed to evaluate fully this possibility.
Fossils of an extinct species of Noctilio are now known from the late Miocene in the Amazon Basin.
Physical characteristics
The muzzle and elongate feet and legs of bulldog bats are their most distinctive features. The nose and muzzle are simple, but a projecting nose-pad, enlarged and swollen lips, pronounced cheek pouches, and folds of skin on the lower lip give these bats a bulldog-like appearance. The ears are separate, long, and narrow, with a lobed tragus. The tail emerges dor-sally from the tail membrane about one-third of its length from the body. The calcar, or heel extension, of these bats is long and bony. Both species have long legs with well-developed feet and claws, but the modification of the claws and feet into large, razor-sharp, and hydrodynamically efficient gaffing mechanisms in Noctilio leporinus is truly astounding.
Bulldog bats are fairly large, with short pelage ranging in color from bright orange to orange-brown and gray-brown. Fur color was previously thought to represent differences between sexes, with males being orange and females brown. It is now understood that color is quite variable within each species. A white line, which may or may not be distinct, runs down the center of the back from the shoulder region to the rump. Wing and tail membranes are brown.
Total body lengths range 2.2–5.1 in (57–132 mm), forearm lengths 2.1–3.6 in (54–92 mm), and weights range 0.6–7.8 oz (18–78 g). Males are significantly larger than females in both species.
Both species have well-developed teeth typical of most insectivorous bats. The dental formula is: I2/1 C1/1 P1/2 M3/3.
Distribution
Bulldog bats are found throughout much of the Neotropics, from southern Mexico to northern Argentina and southeastern Brazil, and in the Antilles.
Habitat
Bulldog bats are found in a variety of habitats, most commonly in moist, tropical lowland areas that are close to water. They have been recorded roosting in hollow trees and sea caves.
Behavior
Information on behavior is limited to general observations on roosting and activity patterns. Few studies of social or mating behaviors have been conducted. The two species differ in activity patterns throughout the night, but are similar in their choice of roosts (hollow trees, caves, and human-made structures), reproductive biology, and general foraging behavior, though N. leporinus preys mainly on fish, and N. albiventris primarily on insects.
Feeding ecology and diet
Noctilio leporinus is best known for its remarkable set of adaptations to piscivory. Only one other bat species worldwide is known to prey on fish: Myotis vivesi (Vespertilionidae). N. albiventris is primarily insectivorous, and N. leporinus also includes a large proportion of insects in the diet. Both species use their large cheek pouches to store partially chewed food, possibly allowing them to continue foraging without having to stop to consume their prey fully, as in most bats.
Bulldog bats use constant frequency and frequencymodulated echolocation to detect prey at the surface of the water and in flight. The rear feet are dragged through the water and used to gaff prey at the surface. The stiff, elongate calcars are used to elevate the tail membrane above the surface of the water, minimizing drag. Prey are sometimes transferred to the tail membrane and then to the mouth during flight.
Reproductive biology
Field studies suggest that females of both species give birth to a single young each year, with the majority of mating in November and December and births occurring in April through June. However, pregnancy and births have been recorded outside of these seasons in different parts of their ranges and a secondary reproductive peak has been recorded for Noctilio leporinus in Cuba. Young are able to fly at about one month of age. Males and females seem to attend the young during their first month of life, suggesting extensive biparental care. A single male typically lives with a harem of females in a polygynous organization. Mating behaviors are unknown, but a warty out-pocket of skin on the scrotum in males, and scent-producing glands associated with it, may be involved.
Conservation status
Populations seem to be stable, although bulldog bats will be negatively affected by water contamination and habitat destruction. Noctilio leporinus has been proposed as an indicator species for water quality because of the likelihood that contaminants will accumulate in their tissues through predation on aquatic insects and fish.
Significance to humans
Bulldog bats eat insects that may be considered pests by humans.
Species accounts
Greater bulldog batLesser bulldog bat
Resources
Books:Hill, John E., and James D. Smith. Bats, A Natural History. London: British Museum of Natural History, 1984.
Koopman, Karl F. "Chiroptera: Systematics." In Handbook of Zoology, Volume VIII, Mammalia, edited by J. Niethammer, H. Schliemann, and D. Starck. Berlin: Walter de Gruyter, 1994.
McKenna, Malcolm C., and Susan K. Bell, eds. Classification of Mammals Above the Species Level. New York: Columbia University Press, 1997.
Nowak, Ronald M. Walker's Bats of the World. Baltimore: Johns Hopkins University Press, 1994.
Simmons, Nancy B., and Jonathan H. Geisler. "Phylogenetic Relationships of Icaronycteris, Archaeonycteris, Hassianycteris, and Palaeochiropteryx to Extant Bat Lineages, with Comments on the Evolution of Echolocation and Foraging Strategies in Microchiroptera." Bulletin of the American Museum of Natural History, Number 235. New York: American Museum of Natural History, 1998.
Periodicals:Altenbach, J. Scott. "Prey Capture by the Fishing Bats Noctilio leporinus and Myotis vivesi." Journal of Mammalogy 70 (1989): 421–424.
Brooke, Anne P. "Diet of the Fishing Bat, Noctilio leporinus (Chiroptera: Noctilionidae)." Journal of Mammalogy 75 (1994): 212–218.
Czaplewski, Nicholas J. "Opossums (Didelphidae) and Bats (Noctilionidae and Molossidae) from the Late Miocene of the Amazon Basin." Journal of Mammalogy 77 (1996): 84–94.
Fenton, M. B., et al. "Activity Patterns and Roost Selection by Noctilio albiventris (Chiroptera: Noctilionidae) in Costa Rica." Journal of Mammalogy 74 (1993): 607–613.
Fish, Frank E., Brad R. Blood, and Brian D. Clark. "Hydrodynamics of the Feet of Fish-catching Bats: Influence of the Water Surface on Drag and Morphological Design." The Journal of Experimental Zoology 258 (1991): 164–173.
Hood, Craig, S., and Jay Pitocchelli. "Noctilio albiventris." Mammalian Species 197 (1983): 1–5.
Hood, Craig S., and J. Knox Jones, Jr. "Noctilio leporinus." Mammalian Species 216 (1984): 1–7.
Lewis-Oritt, Nicole, Ronald A. Van Den Bussche, and Robert J. Baker. "Molecular Evidence for Evolution of Piscivory in Noctilio (Chiroptera: Noctilionidae)." Journal of Mammalogy 82 (2001): 748–759.
Mendez, L., and S. T. Alvarez-Castañeda. "Comparative Analysis of Heavy Metals in Two Species of Ichthyophagous Bats Myotis vivesi and Noctilio leporinus." Environmental Contamination and Toxicology 65 (2000): 51–54.
Roverud, Roald C., and Mark A. Chappell. "Energetic and Thermoregulatory Aspects of Clustering Behavior in the Neotropical Bat Noctilio albiventris." Physiological Zoology 64 (1991): 1527–1541.
Van Den Bussche, Ronald A., and Steven R. Hoofer. "Further Evidence for Inclusion of the New Zealand Short-tailed Bat (Mystacina tuberculata) within Noctilionoidea." Journal of Mammalogy 81 (2000): 865–874.
Van Den Bussche, Ronald A., Steven R. Hoofer, and Nancy B. Simmons. "Phylogenetic Relationships of Mormoopid Bats Using Mitochondrial Gene Sequences and Morphology." Journal of Mammalogy 83 (2002): 40–48.
[Article by: Tanya Dewey]
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