California Department of Fish and Wildlife

Bay Delta Region

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Scott Wilson

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Stanislaus River Report


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Stanislaus River Basin and Calaveras River Water Use Program
Threatened and Endangered Species Report - March 1995
Bay Delta and Special Water Projects Division, CA Dept of Fish and Game

Long-legged Myotis

Myotis volans
Category 2 candidate for listing by the U.S. Fish and Wildlife Service as Threatened or Endangered

Life History

The long-legged myotis is described as having cinnamon red to dark brown fur above and lighter brown to buff below. Hair extends from the body outward to the elbow and knee on the wing and on the interfemoral membrane down to the knee. The forehead is abruptly sloped with a low sagittal crest, the ears are rounded and small, not reaching the muzzle, and it has small feet with a keeled calcar. Body measurements are: total length, 87 to 103 mm; tail, 37 to 49 mm; tibia, 16.5 to 19 mm (Ingles 1965); ear, 11 to 14; forearm, 35.2 to 41.2; greatest length of skull, 12.2 to 15 (Hall 1981).

Myotis volans is found from North Dakota, south through Texas and west to the pacific coast of the United States, central Mexico, Baja California, and central to north western Canada. There are four subspecies described by Hall (1981) with two (M.v.interior and M.v. longicrus) occurring in California.

This is a common bat found in all the mountain ranges of California above 4,000 feet (1200 m) and is excluded only from Californias central valley, the Colorado and Mojave deserts and eastern Lassen and Modoc counties. The long-legged bat can be found in woodland, forest, chaparral, shrub and coastal scrub habitats and is uncommon in arid grassland and desert habitats.

Myotis volans forage near trees and cliffs, over water, and in wooded openings, at ten to 15 feet (3 to 5 m) from the ground. They feed primarily on moths and other flying insects. Emergence is later than other myotis species but still near dusk. Information on winter habits is lacking but probably makes short migrations to hibernating sites.

Roosting sites can be found in rock crevices, buildings, under bark, in snags, and caves. Nursery colonies can be made up of hundreds of bats and are found under the bark of trees or in hollow cavities and occasionally in crevices of rocks or buildings. Mating takes place in the fall and young are born from June to July. Lactating females can be found from July to August and young may begin flying in July.

Findings and Conclusions

This bat is easily disturbed at roost sites and may be causing a decline in the species. The destruction of suitable roosting sites, pesticide use, eradication from buildings and destruction of foraging habitat could also play a critical role.

The long-legged myotis may be found in the upper reaches of the Stanislaus River. Our surveys occurred during the colder part of the year and did not resulted in their capture.

The project should have minimal impacts on the long-legged myotis as long as foraging areas and roosting sites are not destroyed. Further surveys for foraging and roosting areas should be carried out and all sites identified.