Northern Myotis - Myotis septentrionalis
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General Description
Methods for aging individuals by morphological features are limited. Juveniles can be distinguished from adults by the incomplete ossification of the phalangeal epiphyses until late August of the year of their birth (Kunz 1971, Caire et al. 1979). After that time, all are typically classified as adults. The degree of wear of the teeth has been used to determine the relative age of adults (Guthrie 1933), though Hall et al. (1957) found this to be unreliable. Examination of canine teeth and molars of individuals known to be at least 18 or 19 years of age revealed very little wear. In Missouri, the prehibernation fat deposition period occurs from August to October and results in an increase in average weight of 41 to 45% (Caire et al. 1979). By spring, the same study found that both sexes weighed approximately what they had before the prehibernation fat deposition period.
Distribution
Montana Range
Migration
No information from Montana is currently available.
Habitat
In Montana, northern myotis have been located hibernating in an abandoned mine in riverbreaks habitat in Richland County (Swenson and Shanks 1979). Northern myotis (Myotis septentrionalis) prefers cooler hibernacula than Myotis lucifugus and selects narrow crevices in which to hibernate.
Food Habits
No food habits information is available from Montana.
Ecology
During the summer, these bats emerge shortly after sunset to forage. Their activity is bimodal, peaking 1 to 2 hours and 7 to 8 hours after sunset. They are less gregarious than M. lucifugus or other Myotis species.
Reproductive Characteristics
Parturition in Montana may occur in late June or July.
Citations & Sources