Hoary Bat

This forest-dwelling hoary bat comes out at night to feed on insects, using its echolocation to locate prey.

These bats are a member of the vesper bat family. Vesper means “evening” in Latin, which perfectly encapsulates their preferred time of the day. The hoary bat has the largest range of any bat species in the Americas. It can be found in many different habitats between northern Canada and Argentina. Whereas many species of bats congregate together in vast colonies, the hoary bat prefers to roost and even sometimes hunt alone outside of the annual migration season.

5 Incredible Hoary Bat Facts

• Hoary bats rely on echolocation to navigate in flight. By emitting a sharp call, they can identify objects from the way this noise bounces around the surrounding environment.
• The definition of the word hoary is white or gray due to age. While this bat’s natural color has very little to do with age, it is still an apt description of the fur.
• The average flight speed of the hoary bat is about 13 miles per hour, but it can also briefly achieve speeds of 25 miles per hour in short bursts.
• These bats consume 40% of their weight in insects every meal. This is the equivalent of a 150-pound person consuming 60 pounds of food.
• Males and females do not spend a lot of time together outside of the mating season.

Hoary Bat Scientific Name

The scientific name of the hoary bat is Lasiurus cinereus. A member of the vesper bat family, the genus name Lasiurus means hairy tail in Greek. This is an apt description, because the dozen or so members of the genus, including the eastern red bat and the western red bat, have a conspicuous hairy tail. The species name of cinereus is derived from a Latin word meaning ashen or ash-like. This is a clear reference to the white-tipped fur. There are three recognized subspecies of hoary bats, about which more will be said in the habitat section.

A quick note on the bat’s taxonomy: some experts advocate that the hoary bat should represent its own genus, distinct yet closely related to hair-tailed bats, with each subspecies being an independent species, but this standard is not yet widely accepted.

Hoary Bat Appearance

Apart from the blunt and rounded nose, short ears, and hairy tail, the easiest way to identify this species from other types of bats is their unique fur color. They sport brown-gray fur with white tips, giving them the appearance of frost or ash, while the neck has a unique yellow “mane” wrapped around the entire head. The hoary bat is also a relatively large member of its genus. Measuring about 5 to 6 inches from nose to tail, with a relatively lightweight of around an ounce, the body of this bat is about the same size as a big mouse. With its wings fully extended, the entire length of the bat measures about 17 inches from tip to tip. The weight of the female is about 40% heavier than the male.

Hoary Bat Behavior

The hoary bat spends most of the daytime roosting alone and then comes out to hunt shortly after sunset. They can be seen soaring and gliding around treetops, streams, lakeshores, and sometimes even urban areas, looking for insects to consume. While they do sometimes form temporary groups to hunt at night, hoary bats are largely solitary in nature. Their territorial instincts seem to intensify during moments of food scarcity. They make shrill hissing sounds and bare their teeth when guarding their favorite hunting grounds.

Although some members of this species do stay in the north to hibernate, most hoary bats will undertake an epic migration in the fall. Hundreds of these bats will travel together from the northern United States and Canada to the southern US and Central America. Regardless of where they live, hoary bats have a specific strategy to deal with cold weather. When the temperature drops, they can slow their metabolism and wrap their hairy tail around their bodies for insulation to stay warm.

Hoary Bat Habitat

The hoary bat prefers to roost in large trees with dense foliage. This may include coniferous trees, broadleaf trees, heavily mixed forests, open wooded glades, cloud forests, lowland deserts, tundra, and even trees along urban streets and city parks. Regardless, they aren’t particularly choosey about where they roost. They’ve been found in squirrel nests, woodpecker holes, buildings, and caves.

The hoary bat has three distinct subspecies. One subspecies called L. cinereus cinereus is found across much of North America, from Canada to Guatemala. They’re even thought to occur in Alaska, though actual populations have yet to be found there. Another subspecies called L. cinereus villosissimus has a natural range across parts of South America, including the distant Galapagos Islands. The third and final subspecies called L. cinereus semotus is found only in Hawaii; it’s one of the few bat species native to the tropical island chain.

Hoary Bat Predators and Threats

The hoary bat is currently threatened by predators, overuse of pesticides, the loss of roosting sites and tree cover, and collision with wind turbines and other manmade objects, which appear to affect this species more than any other bat, perhaps because it mistakes the turbine for a place to roost. More responsible tree management, new wind turbine technologies, and better conservation practices, in general, should help to maintain existing population numbers.

White-nose syndrome, a fungal disease that has devastated bat numbers in the eastern United States, doesn’t appear to be a significant cause of mortality for the hoary bat. There may be two reasons for this. First, white-nose syndrome is spread by close contact, and the hoary bat is mostly solitary. Second, the fungus itself doesn’t kill the bat directly but instead disturbs the bat’s natural hibernation cycle, which causes it to starve or freeze to death. The hoary bat, by contrast, prefers to migrate south for the winter.

What eats the hoary bat?

The hoary bat is preyed upon by hawks, owls, kestrels, and snakes. The bat’s fur color provides a degree of camouflage while it’s roosting in trees.

What does the hoary bat eat?

The hoary bat feeds almost entirely on insects. Moths appear to account for most of its diet, but it also consumes flies, beetles, grasshoppers, termites, dragonflies, and wasps. As mentioned previously, it consumes 40% of its body weight per meal.

Hoary Bat Reproduction and Life Cycle

There is a lot we still don’t understand about the reproduction of the hoary bat because few people have ever actually seen them mate. But it’s believed that they reproduce sometime around August, either before, during, or after their annual migration. Mating itself probably takes place in the air. After they copulate, the female has the remarkable ability to delay fertilization of the egg by storing the sperm for the winter. Thus, while the gestation period only lasts for a few weeks or months, the female does not give birth until the following late spring or early summer.

The mother will produce around two (and sometimes up to four) pups at a time while she hangs upside down in her roost. She has two pairs of teats to wean all of them at once. The pups are born with brown skin, shading to pale around the head and short tufts of fine silvery fur. They are completely helpless because their eyes and ears are closed for the first few days of their lives. They spend the day clinging to the mother as she sleeps. At night they hang from a twig or leaf as the mother goes out hunting.

Mothers will develop a basic relationship with their pups. She has the ability to recognize their calls, especially when they’re in distress. Some mothers will change roosts frequently with their pups. This is the only time she will actually take them with her on a flight. It takes about a month for the pups to begin flying on their own. By around day 45, they can fly nearly as well as the adults. Their lifespan hasn’t been well-documented, but with the burden of predators and disease, it’s estimated that they only live some six or seven years in the wild, while the average lifespan may be no more than two years. The migratory period seems to be the most dangerous period. Many fall victim to predators, accidents, or collisions during this time.

Hoary Bat Population

The hoary bat is currently classified as a species of least concern by the IUCN Red List. It’s unknown how many hoary bats live in the wild, but the best estimate suggests there are around 2.5 million in North America alone. Local populations (particularly in places like the Galapagos Islands and the Pacific Northwest) may be threatened by human activity. The Hawaii subspecies is specifically classified as endangered. There is, unfortunately, a lot of information lacking about this species, so conservationists are focused on accumulating more data in order to improve efforts at rehabilitation.

1. Animal Diversity Web, Available here: https://animaldiversity.org/accounts/Lasiurus_cinereus/
2. The Wildlife Society, Available here: https://wildlife.org/rapid-declines-raise-concerns-about-hoary-bats-future/
3. Bat Conservation International, Available here: https://www.batcon.org/article/the-little-known-world-of-hoary-bats/