New York Natural Heritage Program
Eastern Small-footed Myotis
Myotis leibii (Audubon and Bachman, 1842)
Mammals

Identifying Characteristics [-]
This is a very small bat with tiny feet. Measurements are as follows: total length of 72-84 mm, tail length of 30-39 mm, hind foot length 6- 8 mm, forearm length of 30-36 mm, and wingspread of 212-248 mm; the weight of an adult is 3-8 g (Banfield 1974, Godin 1977, Schwartz and Schwartz 1981, Merritt 1987). The dorsal pelage is pale yellowish brown to golden brown, the ears are black, and the face has a black mask. The tragus, a fleshy projection at the entrance to the ear, is long and pointed. There are no prominent chin or nose flaps. The belly hair varies from pale buff to whitish. The bases of the hairs on the back are blackish and the wing and tail membranes are very dark brown. The tail reaches the edge of the interfemoral membrane (the membrane that stretches between the legs of bats that is used for flight and for catching insects). The base of this membrane and the undersurfaces of the wing membranes are sparsely furred. The calcar (a cartilaginous extension of the ankle) has a definitive keel. The sexes are similar in appearance.

Characters Most Useful for Identification [-]
The combination of the small size, golden-yellow pelage, and lack of a mask make this bat readily distinguishable from other species of bats in New York. The small hind foot and long-keeled calcar are also diagnostic.

Behavior [-]
Mating behavior is similar to that of the Little Brown Bat (Myotis lucifugus) (Wimsatt 1945) and so, probably, are other facets of reproduction (Banfield 1974). Breeding may occur in the fall, with the sperm stored in the uterus over the winter. Active gestation lasts probably two months, with a single offspring born annually, probably in early July (Merritt 1987). Survival rates are significantly lower for females (42%) than for males (76%) (van Zyll de Jong 1985). One individual is reported to have lived 12 years (Hitchcock 1965). Colonies are usually small (fewer than 15 individuals), although a few number in the hundreds up to approximately 2,000.

Diet [-]
Feeding flights are relatively slow and fluttery and often occur over ponds and streams and along roads.They are known to consume moths (Lepidoptera), true flies (Diptera), and beetles (Coleoptera) (Johnson and Gates 2007, Moosman et al. 2007). Presence of spiders (Araneae) and crickets (Gryllidae) in the diet suggest they may capture some of their prey via gleaning (Moosman et al. 2007).
Eastern Small-footed Myotis Images
click to enlarge
The Best Time to See
Emerges from its daytime retreat shortly after sunset, while there is still some light. In the northeastern U.S., seldom enters hibernation caves before mid-November; departs by March, or possibly earlier in Vermont (Godin 1977).
J F M A M J J A S O N D
Present Active Reproducing
The time of year you would expect to find Eastern Small-footed Myotis present (blue shading), active (green shading) and reproducing (orange shading) in New York.
Similar Species
  • Eastern Pipistrelle (Perimyotis subflavus)
    The Eastern Pipistrelle can be distinguished from the Small-footed Myotis by its pink forearms and lack of a black mask.
  • Indiana Bat (Myotis sodalis)
    The Indiana Bat can be distinguished from the Small-footed Myotis by its slightly larger size, uniform gray-brown pelage, pink nose, and lack of a black mask.
  • Northern Myotis (Myotis septentrionalis)
    The Northern Myotis can be distinguished from the Small-footed Myotis by its slightly larger size, gray-brown pelage, long ears, unkeeled calcar, and lack of a black mask.
  • Little Brown Bat (Myotis lucifugus)
    The Llittle Brown Bat can be distinguished from the Small-footed Myotis by its slightly larger size, brown-white bi-colored pelage, unkeeled calcar, and lack of a black mask.