The hoary bat averages 13 to 14.5 cm (5 to 5.7 in) long with a 40 cm (15.7 in) wingspan and a weight of 26 g (0.9 oz). It is the largest bat normally found in Canada. Its coat is of a dark brown colour and there is silver frosting on its back. With the major exception of the underside of the wing most of the bat is covered in fur.
The bat normally roosts alone on trees (hidden among foliage) but on occasion has been seen in caves with other bats. It prefers woodland, mainly coniferous forests but hunts over open areas or lakes. It hunts alone and its main food source are moths but will eat dragonflies.
The reproductive cycle of the hoary bat is not yet fully documented but it is thought that they mate in August with birth occurring in June of the following year. It is thought that the gestation period is only 40 days and that Mammalian embryonic diapause (delayed implantation) may play a role. Litters range from 1 to 4 and the young spend about one month with the mother before being able to fend for themselves.
The bat is migratory and may travel from Canada as far south as the southern United States or Bermuda. Occasionally the bat will roost inside shipping crates and this may account for reports of them being observed above the Arctic Circle.
There are many families of bats and the hoary bat belongs to the largest family of all, family vespertilionidae. The relatives in this family include the long-eared bats and the mouse eared bats. This family is distinctive for bats that have small eyes and long tails. Furthermore the vespertilionidae family of bats is most closely related to the family molossidae (free tailed bats). These bats are small to moderately large in size and have an unique bony tail that they use to assist them by using it as a sort of ”feeler”. Evidence indicates that bats are more closely related to perissodactyla (eg. whales and elephants), carnivore (eg. dogs/bears and cats) and pangolins (scaly mammals found in Africa and Asia) than to what is usually suspected, mammals belonging to rodentia such as rats/mice, beavers, and porcupines.
A bats wing can be assumed that it is equivalent to a bird’s wing although these structures are analogous. Both wings serve similar purposes although they are structured incredibly differently. This indicates that bats evolved wings following their common ancestor, and therefore there is absolutely no relation to birds. Although bats have homologous features, which include the structure of the bats wing combined with the structure of a dolphins fin. Both these mammals use their similar upper arm bone, lower arm bones and five fingers for different purposes (dolphins fin used for swimming and bats wing for flying). This suggests that these mammals both have evolved from a common ancestor.
The Hoary Bat may also be found in parts of Hawiaii.