New York Natural Heritage Program
Northern Long-eared Bat
Myotis septentrionalis (Trovessart, 1897)

General Description [-]
The northern myotis is a medium-sized brown bat with ears that when flattened extend at least 3 mm beyond the tip of its nose. It has a long pointed tragus. It weighs 6-9 g (0.2-0.3 oz) and has a wingspan of 23-26 cm (9-10 in). Its pelage is medium to dark brown on the back and gray to tawny brown underneath.

Identifying Characteristics [-]
Northern myotis can be distinguished from other Myotis species by their longer ears, longer pointed tragus, larger wing area, and longer tail. They may also be distinguished acoustically, by analyzing echolocations recorded with a bat detector. Occasionally spectrograms, or visual representations of sound frequencies, of their echolocations could appear similar to some other Myotis species especially small-footed (M. leibii) and Indiana bats (M. sodalis) in the northeast.

Best Life Stage for Proper Identification [-]
Adults may be easiest to identify.

Behavior [-]
Northern myotis are nocturnal with periods of heightened activity at pre-dawn and dusk. They maintain large home ranges (although perhaps smaller than some other bat species) to meet their daily energy and resting needs. On study in West Virginia found mean home ranges among females to be 65 ha (range 18-98 ha) (Owen et al. 2003). Northern myotis may roost in small colonies or individually and they switch roosts often (Sasse and Pekins 1996; Carter and Feldhamer 2005).

Northern myotis are short-distance migrants. They have been documented traveling up to 168 miles from hibernacula to summer colonies (Griffin 1945). They have also been documented to move between hibernacula during the winter (U.S. Fish and Wildlife Service 2013).

Genetic research has indicated that there may be male-biased dispersal and site fidelity in females for this species as is common in mammals (Arnold 2007). This means that females often return to the same areas to raise pups and males travel farther than females to find mates. There also appear to be unbalanced sex ratios in favor of males in some regions (NatureServe 2013).

The northern myotis, like most bats, breeds in the fall; they swarm and mate near the cave entrance. Females store sperm over the winter until ovulation occurs in the spring which coincides with emergence from winter hibernacula. Females give birth to one young approximately 50-60 days later (Baker 1983).

Northern myotis obtain insect prey by capturing them out of the air (aerial hawking) and by gleaning them from vegetation. Locating insects by passive detection and gleaning may allow the northern myotis to obtain a wider variety of insect prey than is typically available to echolocating bats (Faure et al. 1993; Caceres and Barclay 2000). Northern myotis typically forage in forests under the canopy but above the understory, or in small openings, or along streams (U.S. Fish and Wildlife Service 2011).

Diet [-]
Northern myotis have a varied diet. They appear to feed primarily on moths, beetles, and flies although other insect orders are consumed as well, and there are regional differences in major prey items. The diet of northern myotis consisted primarily of beetles (Coleoptera 42%) and moths (Lepidoptera 31%) in one study in West Virginia (Carter et al. 2003). Moths (49%) and beetles (38%) were also the primary prey species found in a larger study in the central Appalachians, with lesser amounts of flies (Diptera) and true bugs (Hemiptera) consumed as well (Dodd et al. 2012). In Indiana, northern myotis preyed primarily on flies (38%) but also beetles (25%) and moths (21%) (Whitaker 2004). Dodd et al. (2012) found that overall, 55% of prey was classified as microlepidoptera, indicating the value of tiny often overlooked moths to this species. Data concerning prey selection are not available specifically for New York.
The Best Time to See
Northern myotis are active at dusk during the spring and summer but they are difficult to distinguish from other Myotis species in flight.
Present Active Reproducing
The time of year you would expect to find Northern Long-eared Bat present (blue shading), active (green shading) and reproducing (orange shading) in New York.
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