Lasiurus cinereus (Beauvois)
Color photos by Robert M. Timm.
Description: Hoary bats are the largest Kansas bat, being at least an inch longer than red bats, to which they are related. The wingspread of 407 mm (16 inches) is an impressive sight when hoary bats fly overhead. In addition to its large size, hoary bats may be distinguished from other Kansas bats by: 1) ears which are short and rounded with black edges while the tragus is large, heavy, and triangular, 2) the tail membrane fully furred on the upper surface (as in the red bat), 3) long, brown hair on the dorsum, heavily frosted with grayish white, 4) individual hairs that are basally gray, succeeded by bands of yellow brown, umber brown, and white, 5) a ruff of longer hair on the neck, and 6) a yellowish face. The underparts are more yellowish than the back and only slightly frosted. Juveniles are darker. While there is no seasonal variation in this species, there is considerable individual variation.
Size: Adults may attain the following dimensions: total length 133-150 mm; tail 46-65 mm; hind foot 11-14 mm; ear 17-20 mm; weight 19.5-34.5 grams.
Range and Habitat: Hoary bats are migratory. The first individuals arrive in Kansas from southern coastal states by the latter part of March, with the main population passing through in April and May. Hoary bats returning to their wintering areas pass through Kansas in late September. There are neither breeding nor winter records in Kansas. This bat in uncommon in the state, but is observed and collected more frequently in eastern Kansas than in the western part. It is not as abundant in Kansas as the red bat.
Reproduction: Hoary bats breed in late summer or early autumn. Sperm remain dormant in the female until ovulation in the spring. After a gestation period of uncertain length, two young (rarely three or four even though four nipples are present in the female) are born blind and hairless. The young remain with the female after they are able to fly at the age of one month.
Habits: Hoary bats roost in trees where they hang upside down from the curved claws of their hind feet. They are strictly a tree inhabitant and are rarely found in caves or buildings.
Food: Hoary bats are the last bats to begin foraging in the evening. They have a fast, erratic flight pattern high above the tree tops. Larger nocturnal beetles and moths are consumed in flight. They have been recorded as flying 96 km per hour.
Remarks: Because of its strong flight there are few raptors capable of capturing hoary bats. Mortality may occur when females fall to the ground from trees due to excessive weight of the young, especially when the female is soaked with rain in periods of strong winds and chilling temperatures. Average longevity for hoary bats is six or seven years, but it has a maximum longevity range of 12-14 years.
Return to the Mammals of Kansas index page.