The silver-haired bat can be recognized by the silver tinge on its fur and small round ears. The slow-flying species’ scientific name (Lasionycteris noctivagans) means “night-wandering shaggy bat.”
The bats can be found nearly anywhere in the U.S. and typically roost in trees.
The bats are solitary and roost alone or in small groups, but females group together to form maternity colonies in tree cavities. Mating takes place in early fall, but fertilization is delayed until the following spring.
When it’s time to give birth in early summer, the bat stands upright and holds her tail membrane forward to form a basket to catch the pup as it is born.
Big Brown Bat
Big brown bats (Eptesicus fuscus) have a 14-inch wingspan with a “thumb” and bony “fingers” and can fly 40 mph. Their leathery wings, rounded ears and broad muzzles are black, but their bodies are covered with light to dark brown fur. Big brown bats can live 10 years or longer.
These bats consume vast amounts of insects — including some of the most damaging agricultural pests — increasing crop yields and decreasing pesticide use.
The spotted bat (Euderma maculatum) inhabits the canyons of Owyhee County during the summer and migrates for hibernation. It’s one of the few bats whose echolocation can be heard by humans.
Little Brown Bat
The little brown bat (Myotis lucifugus) — the most common bat in North America — weighs less than half an ounce (about as much as two crayons) and has a wingspan of 9 to 11 inches.
The bats consume mosquitoes and midges by knocking the insects out of the air with the tips of their wings and scooping them into their mouths.
Little brown bats are not territorial and may hibernate with tens of thousands of others. Mating season starts in August, and pups are born two months later. Pups can fly and catch insects at a month old.
Little brown bats live for six or seven years.
The long-legged myotis (Myotis volans) is the most common bat in the western U.S. It is active most of the night, covering great areas of terrain. It doesn’t roost in caves in the summer months.
The Western pipistrelle (Pipestrellus hesperus), with an 8-inch wingspan the smallest bat in the U.S., is a species of special concern in Idaho. The bat emerges before nightfall and stays active after sunrise. It lives 10 to 13 years.
The Yuma myotis (Myotis yumanensis) is more closely associated with water than most bats. In Idaho, the bat inhabits a wide range of territory, including dry deserts and moist forests.
The hoary bat (Lasiurus cinereus) usually gives birth to twins but can have up to four pups each year. The mother sometimes carries her young on her 16-inch wings before they can fly.
Western Small-footed Myotis
The western small-footed myotis (Myotis ciliolabrum), with its tiny feet (1/3-inch long), is one of Idaho’s most common bats.
It has been found in a range of habitats but appears to be abundant in southern Idaho where it hibernates in crevices of lava tubes. It is one of the last bats to begin hibernation in winter.
Mating typically takes place before hibernation. Sperm is stored in the female’s body until ovulation and fertilization take place in the spring. A single pup is born in May, June or July and is ready to fly in one month.
Little is known about the behavior of the California myotis (Myotis californicus) in Idaho.
The small bat has been found in only three counties: Adams, Washington and Payette. But wildlife biologists think the bat is more widespread.
The California myotis is often confused with the Western small-footed myotis, but the cranium is round and not flattened like the small-foot myotis. The upper fur is brownish chestnut and tends to have a yellowish cast.
The bat forages insects five to 10 feet off the ground using a slow, erratic flight pattern.
Mating takes place in the fall; ovulation and fertilization are delayed until spring. Nursery colonies are small, usually around 25. Females have one pup each in early June.
The fringed myotis (Myotis thysanodes) gets its name from the distinct fringe of short, wire-like hairs found on the membrane between its hind legs. It eats beetles on the ground, so its wings have high strength to resist puncture. It inhabits a small area of Idaho from McCall to Lewiston and can live up to 18 years. It is a species of special concern in Idaho.
The long-eared bat (Myotis evotis) is mostly a forest dweller, whose habits and range are not well known in Idaho.
The pallid bat (Antrozous pallidus) catches its prey on the ground or a few feet in the air. It eats large beetles, moths, crickets and small vertebrates. It usually gives birth to twins.
As one would suspect, the Townsend’s big-eared bat (Corynorhinus townsendii) has very long ears — 1.5 inches long. To conserve body heat, the bat tucks its ears under its broad wings.
Its numbers had once appeared to be in decline, making it a species of special concern in Idaho. This is partly because these bats are extremely sensitive to human disturbance. They prefer habitats that are almost completely dark and can be found in mountain forests and dry deserts, away from people.
Recent bat counts show an upturn in the bat’s numbers in south-central Idaho.