Perception Channels: tactile ; chemical
Arita and Ortega (1998) have evaluated the Mexican fishing bat as a species of special concern. Specific dangers to the bat's chances for survival are: it is endemic to Baja, has a specialized diet and habitat, and the rapid transformation of its habitat. Because not much is known about the ecology of the Mexican fishing bat, Arita and Ortega recommend data collection on natural history as well as population statistics. The immediate steps recommended are to protect the immediate area in which the species occurs, as well as manage its roosting and feeding habitats.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: vulnerable
No known adverse affect. Some bats can carry rabies, however, it is not easily transmitted to humans (Fenton, 1992).
No known benefit to humans. Some bats that live in large colonies produce large amounts of guano that can be sold as fertilizer.
The Mexican fishing bat feeds on marine crustaceans and fish. Their fishing behavior is thought to have evolved from feeding on insects floating or swimming in the water. Individuals generally forages over marine lagoons and eat small marine fish, which have a high salt contact. As the bat's habitat is also in an arid region, it has a highly modified urinary system, similar to other organisms that must conserve water. Their digestive tract is similar to that of other carnivorous bat species, with a pyloric region relatively larger than the cardiac region (Altringham, 1996; Hill and Smith, 1984).
The Mexican fishing bat is endemic to the islands and coastal areas on both sides of the Sea of Cortez and the west-central coast of the Baja California peninsula (Arita and Ortega, 1998; Bogan, 1999).
Biogeographic Regions: neotropical (Native )
Myotis vivesi lives on the islands and coastal areas on both sides of the Sea of Cortez and on the west-central coast of the Baja California peninsula. They forage over water in these areas. They roost in caves or rock crevices, and have also been found living under large flat rocks along the beach (Altringham, 1996).
Habitat Regions: tropical ; terrestrial ; saltwater or marine
Terrestrial Biomes: desert or dune ; chaparral
Aquatic Biomes: coastal ; brackish water
Other Habitat Features: estuarine
Average lifespan
Status: wild: 10.0 years.
Average lifespan
Status: captivity: 10.0 years.
The Mexican fishing bat is the largest North American member of the genus Myotis, characterized by long, enlarged and laterally compressed claws on the hind feet, elongate feet and legs. The margin of the plagiopatagium is attached to the side of the foot, as in many other members of the subgenus Leuconoe. The skull has a low braincase and broad rostrum.
The wings of the Mexican fishing bat are long and relatively large, with a high aspect ratio (AR) and low wing load (WL). Wings with high aspect ratio allow for highly efficient flight, however, the ability to maneuver well is compromised. Because the bats forage over open water, maneuverability is not a priority. Low wing load allows the bat to carry heavy loads in flight, so carrying prey items is not a problem. These wing features contribute to the bat's foraging style-- slow, low flight over the open water.
Like other fishing bats, the Mexican fishing bat has very large feet and long claws. The toes and large sharp claws are laterally compressed to minimize drag when skimming through the water to catch a prey item. The bat's long calcar folds forward along the lower portion of the hindlimb, so that the uropatagium is out of the way when the bat is fishing.
The fur is fawn to brown, with dark gray at the base. The underparts are whitish. There are a few hairs at the base of its uropatagium on the underside, but on the dorsal surface there is a relatively thick layer on the distal third of the membrane.
(Altringham, 1996; Hill and Smith, 1984.)
Average mass: 25 g.
Other Physical Features: endothermic ; bilateral symmetry
Average mass: 25 g.
Average basal metabolic rate: 0.199 W.
Testicles are smallest in January, become descended in June, and reach maximum size in October. Mature spermatozoa are found in males from late July through September. Females give birth to a single young in late May to early June, following a gestation period of 55-65 days (Maya, 1968). The seasonal separation of male spermatogenic activity and female gestation suggests that sperm may be stored by the female, as occurs in some other vespertilionid species. Other reproductive data available in Mammalian Species account (Blood and Clark, 1998).
Range number of offspring: 1 to 1.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average number of offspring: 1.
