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.
Myotis vivesi, the fish-eating bat or fish-eating myotis,[3] is a species of bat that lives around the Gulf of California, and feeds on fish and crustaceans. It is the largest species of the genus Myotis in the Americas, and has exceptionally large feet, which it uses in hunting. It was described in 1901 by Auguste Ménégaux. It was previously considered the only member of the Myotis subgenus Pizonyx, but Pizonyx is now considered to contain all American Myotis species, along with two Eurasian ones.[4]
Myotis vivesi is the largest species in the genus Myotis in the Americas,[5][6] and is similar in size to the Eurasian Myotis myotis (greater mouse-eared bat).[7] The skull averages 23 millimetres (0.91 in) in length.[7] The second largest Myotis species in the New World, Myotis velifer, has a skull 17.6 mm (0.69 in) long, and feet 8 mm (0.31 in) long; M. vivesi has greatly elongated hind feet, which average 23 mm (0.91 in) long.[7]
In common with other fish-eating bats, Myotis vivesi has long, efficient wings, with high aspect ratio and low wing loading,[8] and large feet with sharp claws.[9] The uropatagium (the wing surface between the hind legs) bears a fringe of silky hairs of unknown function; the uropatagium itself is used in hunting.[7]
The fur is around 8 mm (0.31 in) long,[7] and varies in colour from fawn to brown, with the base of each hair being dark grey.[5] In common with other piscivorous species of Myotis, the underside of M. vivesi is pale.[7]
Myotis vivesi is found along the coast of the Gulf of California in the Mexican states of Sonora, Baja California and Baja California Sur, mostly on small islands.[1] A small population exists on the Pacific coast of the Baja California peninsula, between Isla Encantada and Punta Coyote.[7] Since it lives on small islands, the range of M. vivesi is naturally fragmented, but data from microsatellites and the mtDNA control region indicate that there is no isolation by distance in the species.[10]
Myotis vivesi feeds chiefly on marine fish[11] or crustaceans,[7] including the squat lobster Pleuroncodes planipes.[12] Only one other bat species, Noctilio leporinus, hunts in marine waters.[13] The guano produced by M. vivesi is red if it has eaten crustaceans, and black if it has eaten fish; green guano and brown guano result from feeding on algae and insects, respectively.[7] As well as fish and crustaceans, M. vivesi also feeds occasionally on aerial insects.[6] M. vivesi can cover large distances when hunting; in 1970, scientists saw "a group of about 400 M. vivesi around a boat at least 7 km [4.3 miles] from the shore".[14] M. vivesi inhabits an arid environment and has evolved the ability to concentrate its urine; this allows it to survive by drinking seawater.[11]
M. vivesi prefers to roost either in caves or under rocks revealed by landslides.[6] They sometimes share their roosts with least petrels (Halocyptena microsoma) and black petrels (Oceanodroma melania).[7] On many islands in the Gulf of California where these petrels nest, the western whiptail is a known predator of their eggs and chicks, and the petrels generally show only fearful responses towards the lizards and capable of doing only little to defend their offspring. However M. vivesi that share roosts with these petrels swiftly react by biting and flapping when the lizards are detected, effectively warding the reptiles off. This may be an example of a symbiotic relationship in which the bats help defend the young of nesting petrels, increasing the chances of survival for petrel chicks. [15]
Myotis vivesi was first described by Auguste Ménégaux in 1901. The species was moved to a new genus, Pizonyx by Gerrit Smith Miller Jr. in 1906,[16] but that taxon is now usually included in Myotis.[17] Ménégaux gave no indication of the etymology of the specific name vivesi; it may either refer to a person called Vives, or derive from the Latin verb vivere, "to live". If Vives was a person, he was not the collector of the specimens, that being recorded as Léon Diguet.[3] No subspecies of M. vivesi have been recognised.[7]
The closest relatives of M. vivesi are other New World species of Myotis which are not adapted to piscivory, rather than the other piscivorous bats in the genus.[16] This indicates that the adaptations to catching fish in M. vivesi and other species are the result of convergent evolution.[16] No fossils attributable to M. vivesi have been discovered.[7] A fossil species of Pizonyx, Pizonyx wheeleri, was named by Walter Dalquest and Daniel Patrick in 1993 from the Miocene of Texas,[18] but according to a 1993 review by Nicholas Czaplewski, this species instead belongs to the genus Antrozous and may not even be distinct from the living species Antrozous pallidus.[19]
{{cite journal}}: Cite journal requires |journal= (help) Myotis vivesi, the fish-eating bat or fish-eating myotis, is a species of bat that lives around the Gulf of California, and feeds on fish and crustaceans. It is the largest species of the genus Myotis in the Americas, and has exceptionally large feet, which it uses in hunting. It was described in 1901 by Auguste Ménégaux. It was previously considered the only member of the Myotis subgenus Pizonyx, but Pizonyx is now considered to contain all American Myotis species, along with two Eurasian ones.
