The silver-haired bat has dark brown or blackish fur that is tipped to some degree with silvery white. The face, ears, and wings are black. This species roosts under loose bark of trees. It is highly migratory and is found statewide during spring and fall migration but is rare in winter and summer.
For your safety and the safety of bats, do not handle bats. Biologists who study bats receive special training and pre-exposure rabies vaccinations. Bats are not aggressive toward people but will bite in self-defense if handled. If you absolutely must handle a bat, wear heavy leather gloves. For more information about bats, see the bats group page.
On silver-haired bats, the fur of both back and belly is blackish brown tipped to some degree with silvery white. This frosted appearance is more conspicuous on the middle of the back and less so on the head and underparts. The wing and tail membranes and the ears are dark brown to black.
The naked ears have rounded tips and are about as wide as they are long. The tragus (projection at the base of the ear hole) is short (less than half the length of the ear), broad, and bluntly rounded. The tail membrane is heavily furred on the upper surface for slightly more than half its length.
Similar species: The silver-haired bat is distinguished from all other bats in Missouri by its coloration. The hoary bat might be confused with the silver-haired bat, since both names imply silvery or whitish fur, but hoary bats are noticeably larger — about twice the weight of silver-haired bats — and they have a yellowish or buffy face, and their fur has more prominent white or silvery tips.
Total length: 90–113 mm (about 3½–4⅜ inches); tail length: 27–50 mm (about 1–3 inches); weight: 5–16 g (about 0.2–0.6 ounces); ear length: 15 mm (½ inch).
Statewide during spring and fall migration; rare during winter and summer.
Habitat and Conservation
Silver-haired bats primarily inhabit trees, so they are found in woodlands and forests and in wooded areas along streams. They usually roost in tree cavities and crevices under tree bark. They can also roost in caves, rock crevices, or buildings.
The silver-haired bat is migratory, moving south in the fall and north in the spring. It apparently flies great distances and migrates in rather large numbers. During its migration it may fly in the daytime as well as at night.
Silver-haired bats range from southeastern Alaska, across southern Canada, throughout most of the United States, and into extreme northeastern Mexico. In general, they winter in the southern part of the range and summer in the northern. They occur irregularly throughout their range, but they are most abundant in forested sections of the western United States.
In Missouri, silver-haired bats can be found statewide during spring and fall migration, but they are rare in winter and summer. They rarely reproduce in Missouri.
Although most individuals of this species migrate, some apparently remain in northern parts of the range. The extent of hibernation is not well understood; some individuals rouse to forage during warmer days and utilize torpor to limit energy expenditures during colder times.
As they forage, they generally fly slow, erratic courses with many twists and frequent, short glides. They fly slowly, with a fluttering quality.
Food
Silver-haired bats mostly eat moths and true flies, including crane flies. They also eat wasps. They often come out to feed just before sunset. They forage along watercourses or the borders of woodlands and forests, darting in and out of the foliage or flying up to 40 feet or more above the ground.
Status
A Missouri species of conservation concern, listed as vulnerable; rated vulnerable to apparently secure across their North American range.
Life Cycle
This is a migratory species, present in Missouri in spring and fall, and only rarely during summer (breeding season) and winter.
Mating occurs in late August or September. During spring the eggs are shed from the ovaries, as is true with other Missouri species of bats. Maternity colonies are typically found in tree cavities of declining or newly dead trees. Gestation occurs over a period of 50–60 days, and twin pups (occasionally 1) are born from mid-June to early July. The young learn to fly and are weaned at 3 to 4 weeks of age.
Control
Human Connections
As with other bat species, silver-haired bats help people by controlling populations of many kinds of pest insects.
Many people harbor a repugnance toward bats, in part due to their association with night, caves, and dark, “creepy” places, but silver-haired bats break the mold. They live and roost in trees, not too differently than many beloved birds and squirrels. The rich dark fur, elegantly white-tipped, is genuinely attractive.
The first part of the scientific name, Lasionycteris, is from two Greek words and means “hairy bat.” This refers to the heavy furring on the upper surface of the tail membrane near the body. The last part, noctivagans, is from two Latin words and means “night wanderer.” The common name comes from the silvery tips of the fur.
Ecosystem Connections
The predator-prey relationship between bats and moths has led moths to evolve many fascinating ways to avoid being captured by bats. Several types of moths, upon sensing the sonar clicks of bats, will immediately, reflexively, engage in erratic flight patterns, or produce sounds that can confuse or jam the bats’ echolocation abilities.
Because they roost and raise their young in cavities and loose bark of dead trees, these bats benefit when landowners allow dead and dying trees (“snags”) to remain standing. Many other cavity-nesting species need hollow places in trees: squirrels, mice, and raccoons, plus many, many birds, including woodpeckers, bluebirds, chickadees, titmice, nuthatches, owls, wrens, chimney swifts, and wood ducks.
The loose bark of dead trees is an important shelter for many types of wildlife, too, and not just for bats. Other animals that rest under loose bark include treefrogs, small snakes, salamanders, and many types of insects, especially as they overwinter as eggs or pupae. Brown creepers — small brown birds that creep around on bark and look like bark — hunt for insects beneath loose bark and also build their nests between the trunk and a piece of peeling bark. Their nests are like little hammocks!
