374.

Eastern Small-footed Myotis

Myotis leibii

French: Murin de Leib / German: Ostliches KleinfuR-Mausohr / Spanish: Ratonero de Leib

Taxonomy. Vespertilio leibu Audubon & Bachman, 1842,

“Erie county, Michigan,” USA.

Subgenus Pyzonix; lucifugus species group. Monotypic.

Distribution. SE Canada in SE Ontario and SW Quebec, and W USA from SE Oklahoma E to New England, W Virginia, and NW South Carolina; distribution 1s irregular, and most occurrences and largest populations are in New York, Pennsylvania, West Virginia, and W Virginia.

Descriptive notes. Head-body c. 40-44 mm, tail 33-38 mm, ear c. 13 mm, hindfoot 5-7 mm, forearm 30-1-35- 3 mm; weight 3-6 g. Fur of the Eastern Small-footed Myotis is long and silky. Dorsal hairs are bicolored, with blackish bases and dark yellowish brown to golden tips; ventral hairs are paler, with dark brown bases and yellowish tan or cinereous tips. Ears are medium-sized and extend slightly beyond nose when laid forward; tragus is long and slender, tapering slightly at tip. Membranes, ears, and skin are blackish. Plagiopatagium is attached to feet by a broad band of membrane; feet are small; and calcar is keeled. Baculum is small and deeply sculptured; slender distal part terminates in slight knob; dorsal and lateral extensions are separated proximally by prominent notch; and bone is somewhat saddle-shaped and concave ventrally and has dorsal prominence. Skull is small and delicate (greatest skull lengths 12-5-13- 9 mm); braincase is flattened; forehead slopes gradually upward from rostrum; occipital region is rounded posteriorly; and sagittal and lambdoidal crests are absent. Chromosomal complement has 2n = 44 and FN = 50, with four pairs of metacentric and 17 pairs of acrocentric autosomes. X- and Y-chromosomes are submetacentric.

Habitat. Mostly hilly or mountainous areas, in or near deciduous or coniferous evergreen forests, sometimes in open agricultural landscapes, mostly at elevations of 700-800 m (but some up to 1125 m.

Food and Feeding. The Eastern Small-footed Myotis forages over water and land, being specialized to catch flying insects 1-3 m aboveground. When foraging,it flies slowly and catchesits prey in flight. It also forages in dense forests by gleaning insects from plants, rocks, or other surfaces. Diets contain lepidopterans, dipterans, coleopterans, hymenopterans, trichopterans, hemipterans, orthopterans, homopterans, psocopterans, neuropterans, and other arthropods (e.g. spiders Araneae).

Breeding. Eastern Small-footed Myotis swarm in hibernacula, and mate selection occurs from late summer through early autumn. It is polygynandrous, and males and females have many mates. Copulation occurs in late autumn, just before individuals hibernate. Females store sperm while hibernation from mid-November to March. Mating during winter was reported when a male and a female arouse from hibernation at the same time. Female have one young each year in May-July.

Activity patterns. The Eastern Small-footed Myotis emerges around dusk in summer. Activity peak occurs immediately after sunset. It roosts during spring and summer in buildings, expansion joints of bridges overrivers, caves, coal mines, hollow trees, spaces beneath loose bark of trees, tunnels, rock crevices, and rocky outcrops and under rocks. In winter,it hibernates in caves and mines and prefers cold and dry locations near entrances.

Movements, Home range and Social organization. Eastern Small-footed Myotis travel a maximum of 1- 1 km within their home range. There is no evidence of migration. They have remarkable homing behavior, returning to the same cave to hibernate even if placed in a different location. Individuals typically switch roosts daily, which requires an abundance of adequate roosting locations within a home range. Males and females select roosts differently, and their preferences change during the reproductive season. In winter, they hibernate alone or occasionally in small clusters, but many can be packed into a crevice, with up to 142 individuals recorded in a cave in Ontario. The Eastern Smallfooted Myotis hibernates horizontally rather than vertically and sometimes hibernate on cave floors.

Status and Conservation. Classified as Endangered on The IUCN Red List. The Eastern Small-footed Myotis has been substantial impacted by White-nose Syndrome. It has likely declined by more than 70% over its distribution in eastern North America over three generations (18 years). It has always been considered to be relatively rare, and some populations experienced declines before the onset of White-nose Syndrome.

Bibliography. Barbour & Davis (1969), Best & Jennings (1997), Chapman (2007b), Johnson & Gates (2007, 2008), Moosman et al. (2007), O'Keefe & LaVoie (2011), Simmons (2005), Solari (2018q).