246.

Townsend's Big-eared Bat

Corynorhinus townsendii

French: Oreillard de Townsend / German: Townsend-Langohr / Spanish: Orejudo de Townsend

Taxonomy. Plecotus townsendii Cooper, 1837,

“Columbia River.” Restricted by C. O. Handley,Jr. in 1959 to Fort Vancouver, Clark County, Washington, USA .

Originally described in Plecotus, but morphological, karyological, and molecular analyses indicated its distinctness from Old World Plecotus, supporting its inclusion in Corynorhinus . Five subspecies recognized.

Subspecies and Distribution.

C. t. townsendii Cooper, 1837 — broadly distributed from SW Canada (British Columbia including Vancouver I) S along Pacific coast of USA to coastal regions of Sonoran Desert in Mexico, and E to Colorado Plateau and Black Hills.

C. t. australis Handley, 1955 — SC USA (W Texas) S across mountains of N & C Mexico and Chihuahuan Desert to Oaxaca.

C. t. ingens Handley, 1955 — S Missouri, E Oklahoma, and NW Arkansas (C USA).

C. t. pallescens G. S. Miller, 1897 — S Wyoming or N Colorado S to New Mexico (USA).

C. t. virgitnianus Handley, 1955 — C Appalachian Highlands in E Kentucky, W Virginia, and West Virginia (E USA).

Descriptive notes. Head—body ¢. 55-58 mm, tail 35-54 mm, ear 30-39 mm, hindfoot 9-13 mm, forearm 39-2-47- 6 mm; weight 5-13 g. Females larger and heavier than males. Fur is long; dorsal hairs bicolored, with blackish bases and tips ranging from yellowish and cinnamon brown to slate gray; ventral hairs bicolored, with strongly contrasting dark brown bases and buff or pale brown tips. Ears large and connected by low band across forehead; tragus long (usually over 13 mm). There are two large glands on either side of muzzle, as in Rafinesque’s Big-eared Bat ( C. rafinesquii); snout is short, with posteriorly elongated nostrils; accessory basal lobe of auricle is absent. Ears, face, and membranes are mummy brown. Plagiopatagium broadly attached to foot at level of base of toes. Skull moderate in size (greatest skull length 15-3-17- 2 mm), slender, and highly arched; rostrum reduced; lacrimal region smoothly rounded; supraorbital region not ridged; temporal ridges normally coalesced to form sagittal crest. Median post-palatal process triangular, with broad base; I* has prominent secondary cusp; anterointernal cusp usually present on cingulum of P* and P* is usually simple. Chromosomal complement has 2n = 32 and FN = 50, with 10 pairs of metacentric and submetacentric and five pairs of acrocentric autosomes, and acrocentric X- and Y-chromosomes.

Habitat. Occurs in wide variety of habitats, such as evergreen forests, deciduousforests, pine-oak forests, xeric shrub-grassland, and gypsum caves in the mid-grass prairie; also found in desert and other arid and semiarid habitats. Occupies an elevation range of 450-3300 m, but commoner in highlands.

Food and Feeding. Diet consists mainly of lepidopterans (over 80%), but also other small insects, such as coleopterans and dipterans. It forages in dense forests, taking insects from among tree branches, and in open fields, over water bodies, and along low cliff walls.

Breeding. Females have a short proestrus in late summer; estrus occurs in autumn, with copulation in November-February. Bats mate with multiple partners repeatedly during the breeding season. Male performs mating display and approaches female performing several vocalizations repeatedly; if accepted by the female, the male rubs his snout over the female’s face, neck, forearms, and ventral surface. The muzzle’s glands serve to scent-mark the female prior to copulation, during which the female is usually in torpor. Sperm is stored in the reproductive tract of females until spring, when ovulation, implantation, and gestation occur. Gestation period is 56-100 days, strongly depending on ambient temperatures and the time the female spends in torpor during gestation. In spring and summer, females form maternity colonies, while males live solitarily or in small bachelor clusters. Most females give birth to only one young. Young females mate in their first autumn, while males do not mate until their second year.

Activity patterns. Reports indicate 1-3 foraging periods per night. Unimodal foraging pattern occurs in spring, but a progressive shift from bimodal to trimodal foraging has been observed in females from late pregnancy through lactation; this shift probably occurs in response to increased energy costs associated with breeding. Roosts are at limestone caves, cliffs, rock ledges, lava tubes, abandoned mines, bridges, and other man-made structures. Wing morphology and echolocation frequency are typical of gleaning insectivorous bats. Call parameters (mean) are: minimum frequency 19-1 kHz, maximum frequency 39-8 kHz, peak frequency 34-7 kHz, bandwidth 20-3 kHz, and call duration 3-3 milliseconds.

Movements, Home range and Social organization. [Longest recorded movement was 64- 4 km between Kentucky and West Virginia. Home range is small to medium-sized (0-8- 24 km?) compared to other bat species. Within home range, bats may have several roost sites for maternity or bachelor colonies, and hibernacula. Females tend to extend their foraging range during gestation; they form nursery colonies in summer, while males are typically solitary or form small groups. Sometimes both sexes live in the same summer roost, although they do not normally cluster together. Colony size varies geographically: western populations usually live in colonies of 10-300 bats; in east, colonies can number 1000 or more. Sometimes roosts with other bat species, including Rafinesque’s Big-eared Bat.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Widespread, with expected large population, and occurs in a number of protected areas; not thought to be declining. However, races ingens and virginianus are listed as endangered by the US Fish and Wildlife Service.

Bibliography. Arroyo-Cabrales & Alvarez-Castafieda (2017d), Barbour & Davis (1969), Bogdanowicz et al. (1998), Burfod & Lacki (1995), Chapman (2007a), Dodd et al. (2008), Hall (1981), Handley (1955b, 1959), Kunz & Martin (1982), Piaggio & Perkins (2005), Simmons (2005), Wilson & Ruff (1999).