397.

Cave Myotis

Myotis velifer

French: Murin des grottes / German: Hohlenmausohr / Spanish: Ratonero de las cavernas

Taxonomy. Vespertilio velifer J. A. Allen, 1890,

“Sta. [= Santa] Cruz del Valle, Guadalajara, Jalisco,” Mexico.

Subgenus Pizonyx; albescens species group. Three subspecies recognized.

Subspecies and Distribution. M.v.veliferJ.A.Allen,1890—-fromSAri-zona(USA)toHonduras.

M.v.grandisHayward,1970—CUSA,fromSNebraskatoOklahomaandNTexas.

M. v. incautusJ. A. Allen, 1896 — S USA,in S Texas and NW Mexico.

Descriptive notes. Head-body c¢. 45-54 mm, tail 35-55 mm, hindfoot 7-12 mm, forearm 36- 5—47 mm; weight 6-11 g. Females are significantly larger than males. Fur is long and silky. Dorsal hairs are bicolored, with blackish bases and dark brown to light brown or sepia tips. Ventral hairs are paler, with darkish bases and bufftips. Ears are comparatively medium-sized (length 13-17 mm), have lobe in base of internal edge, and extend beyond tip of nose. Membranes are mummy brown. Plagiopatagium is attached to feet by a broad band of membrane, and upper and lower surfaces of uropatagium are barely covered with hairs. Skull is robust and large (greatest length of skull 14-2-17- 6 mm); rostrum is broad dorsally butlittle less than that of braincase; sagittal crest is well developed; and lambdoidal crests are present, ranging from low to high. Molars are robust and large; width compared with palatine is greater than in any other American Myotis . Chromosomal complement has 2n = 44 and FN = 50 with one pair of small biarmed autosomes, three pairs of large biarmed autosomes, and 17 acrocentric pairs of varying size. X- and Y-chromosomes are submetacentric.

Habitat. Wide variety of habitats including deciduous rainforests, thorny rainforests, xeric scrublands, oak forests, pine forests, fir forests, and disturbed environments (e.g. agricultural mosaics and suburban areas) from sea level up to elevations above 3000 m.

Food and Feeding. The Cave Myotis forages just above vegetation, capturing prey in flight. Individuals forage more in open areas adjacent to wooded vegetation and high over canyon systems on warmer nights but closer to dense vegetation on cooler nights. Diets vary by season and habitat. In Arizona and northern Mexico, small moths ( Lepidoptera) are most commonly consumed; in Kansas, beetles ( Coleoptera) are more common in stomachs than moths, but variation in prey species did occur over time. Other insects (e.g. Diptera, Hemiptera, and Hymenoptera) occur in diets.

Breeding. Mating of the Cave Myotis occurs in hibernacula in autumn, and copulations are probably repeated during wakeful periods in winter. Sperm are stored in uterus during winter, and ovulation and fertilization occurs in April after females awake from hibernation. Females form maternity colonies in warmer parts of caves, under bridges, and in other locations. Maternal colonies with males present have been reported, but there is a tendency to sexually segregate after young are born. Gestation lasts ¢.60-70 days, with one young being born in late June or early July in northern populations and mid-April and May in southern populations. Neonates are ¢.25% of adult weight, which is reached at c.9 weeks of age. Young initiated flight at c.3 weeks old, and they began to forage at c.4 weeks. Males might not become reproductively active until their second year, and spermatogenesis occurs in late summer and early autumn. Females become reproductively active in their first year oflife.

Activity patterns. Cave Myotis emerge from diurnal roosts ¢.30 minutes after sunset, depending on cloud cover, vegetation, topography, and season. Normally, they feed twice during the night, with major period of activity soon after sunset and shorter period just before sunrise. Nearly 80% of daily food consumption occursin the first two hours after initial emergence. Apparently, most individuals move directly to a stream or other water resource to drink shortly after emerging. Cave Myotis roost in caves but occasionally in crevices in rocks and walls, mine tunnels, and old buildings and under bridges. In winter, they seem to prefer caves with high humidity and permanent streams.

Movements, Home range and Social organization. There is evidence that Cave Myotis have home ranges of several hundred square kilometers during non-migratory times of the year. In a field experiment, more than 50% of individuals released c. 60 km from their hibernaculum was able to return, although other caves were closer to the release area. There is also evidence of individuals returning to the same locality every year during the reproductive season. Populations from Kansas and Texas appear to be permanent residents, hibernating in caves during winter. Few seem to overwinter to California and Arizona, suggesting they move south. Populations in Mexico migrate to higher elevations in winter to hibernate. Colonies generally have 2000-5000 individuals but sometimes as many as 20,000 individuals. They can occur in close association with other bat species, such as the Brazilian Free-tailed Bat (Tadarida brasiliensis) and the Yuma Myotis (M. yumanensis).

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Cave Myotis is widespread and presumably has a large population.

Bibliography. Castro-Campillo et al. (2014), Davis, R. (1966), Davis, R. & Cockrum (1965), Dunnigan & Fitch 1967), Fitch et al. (1981), Hall & Dalquest (1963), Hayward (1970), Krutzsch (1961), Kunz (1973b, 1974), Solari 2019k), Tinkle & Patterson (1965), Wilson & Ruff (1999).