Fish-eating mouse-eared mouse
| Fish-eating mouse-eared mouse | ||||||||||||
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| Myotis vivesi | ||||||||||||
| Ménégaux , 1901 |
The fish-eating mouse- eared bat ( Myotis vivesi ) is a bat species from the smooth-nosed family (Vespertilionidae), which is native to Mexico and the only representative of the Pizonyx subgenus . She is known for her crustacean and fish-based diet. The species name is derived from the Latin "vivo" (= to live).
description
With a total length of 145 mm and a forearm length of 62 mm, the fish-eating mouse-eared mouse is the largest representative of the mouse-eared group . Its appearance is similar to that of the Eurasian great mouse-eared mouse, but it has much larger feet averaging 23 mm in length. The feet are the same length as the tibia . They protrude from the skin , which only begins at knee level. The ears protrude about 5 mm above the muzzle when put forward and usually have four grooves. The fur is grayish with a significantly lighter underside. The wings are long and slender at the tips, which is typical of bats that fly in relatively open air space with few obstacles. The wings also have nodes with hemopoietic (blood-forming) cells, which is unique to mouse ears. The red blood cells of Myotis vivesi are 4.6 µm in diameter, a normal mammalian size, while the blood cells of other mouse ears are over 6 µm in diameter.
Way of life
The fish-eating mouse-eared mouse is known for its diet, which is mainly based on fish and crustaceans . In fact, crustaceans and not fish, as is often believed, make up the majority of the diet. The extended feet and claws are the ideal tool for this, similar to the Neotropical Big Hare's Mouth ( Noctilio leporinus ). Feet and tail skin are pulled through the top layer of water in flight and the prey is fished out with it. The echolocation calls of the fish-eating mouse-eared mouse range between 20 and 45 kHz and are therefore partially audible to humans . The animals utter 10–20 calls per second, which condense and become higher as soon as they spot prey on the surface of the water. During the day the fish-eating mouse-ear hides in crevices and caves. The same columns are often used by the dwarf petrel ( Halocyptena microsoma ) and the Black Petrel ( Oceanodroma melania used) as a nesting site. These two seabirds benefit from the association with the fish-eating mouse-eared mouse, as their presence appears to preclude large lizards from preying on eggs. However, it is believed that Myotis vivesi will only be in the same crevices if there are no other suitable resting places.
Since there are the islands where the fish-eating mouse ear occurs mostly no other mammals, are barn owls ( Tyto alba ) is the most important predators of this type. Other predators are birds such as the loggerhead shrike ( Lanius ludovicianus ), the ring-billed gull ( Larus delawarensis ) that Western gull ( Larus occidentalis ), the common raven ( Corvus corax ), the peregrine falcon ( Falco peregrinus ) and the osprey ( Pandion haliaetus ). In addition, introduced predators such as the house cat ( Felis catus ) and the brown rat ( Rattus norvegicus ) are increasingly becoming a problem.
Reproduction
After a gestation period of 55–65 days, the females give birth to a single young in May or the first week of June. The newborns weigh between 5.9 and 6.6 g and are born with eyes closed, which, however, open on the third day after birth. For the first three weeks after birth, the young hang on the mother's teat, but are left behind in the nursery by the females on foraging flights. After 50 days, the young can fly independently and leave the hanging place at night.
distribution and habitat
The fish-eating mouse-eared mouse is found in the coastal area and on most of the islands in the Gulf of California ( Mexico ). There the species often looks for gaps in rock slides, but can still be found in caves and crevices. In the event of disturbances, it seeks protection in various places, such as under flat stones or turtle shells . The population is classified as endangered ("vulnerable") by the IUCN because of its small distribution area. The populations are declining and probably consist of a maximum of 15,000 individuals.
literature
- BR Blood & MK Clark (1998): Myotis vivesi . In: Mammalian Species , No. 588, pp. 1-5
swell
- ↑ Myotis vivesi in the IUCN Red List of Threatened Species .
