Myotis melanorhinus

373.

Dark-nosed Small-footed Myotis

Myotis melanorhinus

French: Murin a face noire / German: Dunkelnasen-Kleinfufs-Mausohr / Spanish: Ratonero de cara negra

Taxonomy. Vespertilio melanorhinus Merriam, 1890,

“San Francisco Mountain, Arizona,” USA.

Subgenus Pyzonix; lucifugus species group. Myotis melanorhinus was previously a subspecies of M. leibii and later M. ciliolabrum. Morphology and morphometric characters support its full species status. Monotypic.

Distribution. Widely in North America, from SE British Columbia (Canada) S through W & C USA to C Mexico.

Descriptive notes. Head-body c. 40-44 mm, tail 29-41 mm, ear 10-13 mm, hindfoot 5-9 mm, forearm 32-35- 3 mm; weight 3-5 g. The Dark-nosed Small-footed Myotis is morphologically similar to the Eastern Small-footed Myotis (M. leibir). Furis long,silky, and usually glossy. Dorsal hairs are bicolored, with dark brown bases and dark buff to yellowish brown tips. Ventral hairs are paler, with blackish bases and yellowish tan or cinereous tips. Ears are medium to long, reaching tip of nose or slightly exceeding it when extended forward; tragus is long and slender, tapering slightly at tip. Membranes, ears, and face are black. Plagiopatagium is attached to feet by a broad band of membrane; calcar has pronounced keel-shaped extension. Skull is small (greatest skull length less than 15- 9 mm); frontal area of skull rises gently from rostrum; braincase is flattened; occipital region is rounded posteriorly; and sagittal and lambdoidal crests are absent. Teeth are large, upper incisors are smaller, and premolars and molars are larger.

Habitat. Primary and secondary vegetation, including pine-oak forests, tropical deciduous forests with numerous cacti, grasslands, xerophytic scrub, and cultivated areas at elevations of 500-2400 m. The Dark-nosed Small-footed Myotis seems to prefer arid habitats where it is associated with cliffs and talus fields; in prairies, it is associated with clay buttes and steep riverbanks.

Food and Feeding. The Dark-nosed Small-footed Myotis is an aerial insectivore that flies slowly and erratically while foraging among trees or over water. Prey is caught and ingested in flight. Diet includes various flying insects, particularly moths (Lepidoptera), but also flies (Diptera), bugs (Hemiptera), beetles (Coleoptera), and caddisflies (Trichoptera).

Breeding. The Dark-nosed Small-footed Myotis is probably seasonal monoestrous. In northern populations, mating occurs shortly before hibernation, and females store sperm. Gestation lasts about two months; births usually occur in early summer. Females give birth to one young, with some reports of twins. In Mexico, lactating females were reported in May.

Activity patterns. The Dark-nosed Smallfooted Myotis begins its activity shortly after sunset with peaks of activity in the first three hours of the night. It hibernates in caves, mines, and rock crevices for periods of about five months from the end of November to beginning of April. The Dark-nosed Small-footed Myotis roosts in rock crevices, clay banks, caves, mines, tree holes, spaces beneath and between boulders in talus fields, and roofs of abandoned buildings and under bark. In Washington, calls are FM and short (1-3 milliseconds), sweeping from 60 kHz to 40 kHz.

Movements, Home range and Social organization. Dark-nosed Small-footed Myotis in Oregon moved 6-24 km round trip from roosts to foraging areas. There is a high fidelity to feeding areas, but roost switching within those areasis frequent. During hibernation, it forms small groups of both sexes located near entrances of caves (or other hibernacula). In summer, females form small maternity colonies located in rock crevices.

Status and Conservation. Classified as Least Concern on The [UCN Red List. The Darknosed Smallfooted Myotis is widespread but considered uncommon in most ofits distribution, occurs in several protected areas, and is unlikely to be declining at a rate to qualify for listing in a threatened category.

Bibliography. Alvarez (2014), Arroyo-Cabrales & Alvarez-Castafieda (2017i), Halloway & Barclay (2001), Harvey et al. (2011), Holloway & Barclay (2001), Merriam (1890), Rodhouse & Hyde (2014), Sanchez-Hernandez et al. (2016), Thomas et al. (1987), van Zyll de Jong (1985).