New York Natural Heritage Program
Silver-haired Bat
Lasionycteris noctivagans (Le Conte, 1831)

General Description [-]
The silver-haired bat is a medium-sized bat, weighing 8-15 g with a wingspan of 27-31 cm (10.6-12.2 in). Its pelage is dark gray, brown or black underneath and light gray or silver-tipped (Harvey et al. 2011). Its ears are short and round with a blunt tragus (Whitaker and Hamilton 1998) and its ears, tail, wings, and the flight membrane between the legs are black (Kunz 1982).

Identifying Characteristics [-]
The silver-haired bat can be distinguished by its pelage which is dark gray underneath and silver-tipped giving it a frosted appearance, especially in younger individuals (Kunz 1982). It differs from the hoary bat which is much larger and lighter in color and has gray-tipped yellowish-brown fur and a yellow throat (Saunders 1988).

Best Life Stage for Proper Identification [-]
Adults may be identified by the frosted appearance of their pelage. This may vary since older individuals may appear less frosted.

Behavior [-]
Silver-haired bats are nocturnal with periods of heightened activity at pre-dawn and dusk. They may emerge from their roosts to forage before sunset (Saunders 1988). Their flight pattern is slow and irregular with wing flapping interspersed with short glides (Saunders 1988). Merriam (1886), however, reported that their flight was less irregular than hoary (Lasiurus cinereus) or red (L. borealis) bats.

Silver-haired bats breed in late September and fertilization occurs in spring. Females give birth to one, or more frequently, two young 50-60 days later in early summer (Parsons et al. 1986; NatureServe 2013).

Silver-haired bats roost individually except for reproductive females which may roost in very small colonies with a few other reproductive females (Wisconsin Department of Natural Resources n.d.; Parsons et al. 1986; US army unpublished data). Segregation of the sexes by habitat and perhaps even by distribution during the summer months has been reported for silver-haired bats (Merriam 1886; Cryan 2003; Kurta 2010).

Diet [-]
Relatively little information has been reported for silver-haired bats on diet and none from New York State. Studies from elsewhere suggest that they consume a variety of invertebrates with moths making up roughly half of their diet. Carter et al. (2003) examined fecal pellets from 2 silver-haired bats in West Virginia and found that they had consumed primarily Lepidoptera (47%) with lesser amounts of Coleoptera, Homoptera, and Diptera. Reimer et al. (2010) studied the stomach contents of migrating adult and juvenile silver-haired bats that had died after colliding with wind turbines in Alberta, Canada. They found that the major food items were Lepidoptera (39% adults, 53% juveniles) and Diptera (33% adults, 15% juveniles) with less than 10% each composition of Hemiptera, Coleoptera, and Homoptera.
The Best Time to See
Silver-haired bats are migratory and are only present in New York from approximately May-August with migrants passing through in April-May and August-September. Silver-haired bats may emerge from the roost earlier in the evening than other species (Merriam 1886; Godin 1977:19) but it would be difficult for a novice observer to distinguish them from other species of a similar size.
Present Reproducing
The time of year you would expect to find Silver-haired Bat present (blue shading) and reproducing (orange shading) in New York.
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