371.

South-western Myotis

Myotis auriculus

French: Murin du Mexique / German: Mexiko-Mausohr / Spanish: Ratonero de México

Taxonomy. Myotis evotis auriculus R. H. Baker & Stains, 1955,

“ 10 mi. [= 16 km] Wand 2 mi. |= 3- 2 km] S Piedra, 1200 {t. [= 366 m], Sierra de Tamaulipas, Tamaulipas,” Mexico.

Subgenus Pyzonux; lucifugus species group. Two subspecies recognized.

Subspecies and Distribution.

M.a.auriculusBR.H.Baker&Stains,1955-EsideofSierraMadreOrientalfromNuevoLeonintoTamaulipasandVeracruz(Mexico).

M. a. apache Hoffmeister & Krutzsch, 1955 — from the mountains of SE Arizona and SW New Mexico (USA) S to Jalisco (Mexico); also in N Coahuila (Mexico). There is a record from Guatemala, but geographic discontinuity and absence of new records in almost 40 years indicates need for taxonomic revision ofthis specimen.

Descriptive notes. Head-body c. 51-52 mm, tail 34-49 mm, ear 18-22 mm, hindfoot 8-10 mm, forearm 37-3-40- 2 mm; weight 6-8 g. Fur of the South-western Myotis is long and woolly. Dorsal hairs are bicolored, with dark brown bases and dull brown to yellowish brown tips; ventral hairs are paler, with dark brown bases and cinnamon buff to light yellow tips. Nominate auriculus is darker overall than subspecies apache. Ears are notably long; tragus is narrow and pointed. Membranes, ears, and skin are mummy brown. Plagiopatagium is attached to feet by a broad band of membrane, and calcar has no keel. Fringe of hairs along trailing edge of uropatagium is absent, and upper and lower surfaces of uropatagium are barely covered with hair. Baculum is saddle-shaped, with large distal knob. Skull is relatively large (greatest skull lengths 15-8-16- 4 mm), with inflated frontal region; parietal is normally inclined forward; occipital region is generally rounded posteriorly; braincase is globose; sagittal and lambdoidal crests are present and relatively well developed; and median post-palatal process is long and rounded. Chromosomal complement has 2n = 44 and FN = 52.

Habitat. Pine-oak forests and savannas, dry forests, mesquite and chaparral forests, desert scrubs, and ponderosa pine, pinyon-juniper, sycamore, rabbitbrush, and cottonwood habitats from lowlands up to elevations of ¢. 2200 m. The South-western Myotis seems to be more associated with extensive rocky cliffs where some wateris available. Males appear to spend more time in marginal upland habitat; females concentrate their activities along streams.

Food and Feeding. The South-western Myotis is forages in forests, open habitats, and near water bodies. Its diet includes mostly small moths ( Lepidoptera), gleaned from tree trunks or walls of buildings. It will briefly land on substrate to pick the insect off of the surface.

Breeding. Female South-western Myotis have one young in June or earlyJuly, but births occur later in southernmost populations. Pregnant females have been observed inside caves in New Mexico, probably their maternity roosts.

Activity patterns. Activity of the South-western Myotisusually begins 1-2 hours after sunset, later than most Myotis . It is most active in two first hours after emergence but also has other activity peaks throughout the night. Roosts include caves, woodpecker holes, rotten ends of sycamore branches and other small tree cavities, mines, and abandoned buildings. It has not been found in hibernacula. Calls are FM, with peculiar initial upsweep, have most energy at 60 kHz, and are short and of low intensity compared with congeners.

Movements, Home range and Social organization. The South-western Myotis migrates seasonally to wintering areas.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Southwestern Myotis is widespread, presumably has a large population, occurs in protected areas,is tolerate to some degree of habitat modification, and is unlikely to be declining at a rate to qualify forlisting in a threatened category.

Bibliography. Arroyo-Cabrales et al. (2017), Baker, R.H. & Stains (1955), Baker, R.J. & Jordan (1970), Barbour & Davis (1969), Cockrum & Cross (1965), Hoffmann et al. (1987), Morrell et al. (1999), Reid (2009), Uribe & Arita (2014), Warner (1982), Wilson & Ruff (1999).