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Lasiurus cinereus - Hoary Bat


Lasiurus cinereus is a member of the suborder Microchiroptera and the family Vespertilionidae (evening or plain-nosed bats) (Schober and Grimmberger 1997).  It is a large bat with a striking appearance. It is the most widely distributed bat of North America, believed to be found in all fifty states, although it is uncommon in the eastern United States.  It is the only indigenous land mammal to Hawaii, and is found on the Galapagos Islands (Tuttle 1988).  Lasiurus cinereus resembles the red bat (Lasiurus borealis) in general structure and heaviness of body type, however it is three times larger by weight.  The impressive size and wingspan of this bat makes it a powerful flyer, capable of covering long distances. It has fine, dense fur that ranges from gray to chocolate brown with white tips to each hair, which gives the bat an appearance of being covered by hoar frost.  There is fur on the entire dorsal side of the tail membrane, as well as patches along the underside of the wing bones. Ears are large, round and rimmed with black fur. There is a ruff of longer fur around neck and shoulders, and a yellowish patch of shorter fur, which lacks the white frosting, at the throat. Lasiurus cinereus is unique from most bats in that it has four nipples instead of two. Females’ mass is approximately 40 % greater than that of males (Shump and Shump 1982). The skull is broad and heavy, with a short, broad rostrum, a flared maxillary region with a wide nares opening, widespread zygomatic arches, a broad interorbitally, and a large braincase (Jackson 1961).


       Total length- 130-150mm

                           Tail length-  53-64 mm

                           Length of forearm- 46-56 mm

                           Hindfoot length- 10- 14 mm

                           Ear height- 17-19 mm

                           Weight- 25-35 g                    (Kurta 1995)

                           Wingspan- 380-410mm         (Tuttle 1988)


Lasiurus cinereus is distributed throughout Wisconsin, although they are believed to be more prevalent in the northern part of the state where coniferous forests, their preferred habitat, are abundant (Jackson 1961).  It is a seasonal resident of Wisconsin, arriving in April and leaving by early November, migrating as far south as Mexico and Central America during the winter (Kurta 1995).

Ontogeny and Reproduction:

Lasiurus cinereus breed in late summer and early fall, often courting each other in flight.  Because fertilization is delayed, young are not born until the following June.  Gestation is therefore 60-90 days long. Litters are usually of two offspring, although litters of three and four are not uncommon.  Because it is a solitary bat that uses exposed roosts, females that bear larger litters are better able to forage than those which only bare one young, as the young are able to keep each other warm in the mother’s absence. Young bats are born with a faint covering of silvery hair and weigh approximately 4.5 g. at birth.   Young bats fledge at 30 days of age (Barclay 1989).

Ecology and Behavior:

Lasiurus cinereus is a solitary bat (like Lasiurus borealis) that roosts primarily in coniferous trees (pine, spruce and hemlock) (Jackson 1961), although any tree that provides dense shade and seclusion with a roosting site 2-6 m from the ground can be used. Its coloring allows for it to be well camouflaged with the bark of trees, and it is a difficult bat to locate. It primarily feeds upon large insects such as moths, beetles and dragonflies.  Its use of low-frequency echolocation calls directs it to this larger prey (Barclay 1985).  Unlike most other bats that leave their roosts to feed at twilight, Lasiurus cinereus begins feeding up to five hours after sundown. Because of its long wingspan, Lasiurus cinereus cannot maneuver with as much agility as other bats, and so it tends to feed along the length of riverbeds and other open areas that are free from dense obstructions (Kurta 1995.)

Literature Cited:

Barclay, R.  985.  Long- versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats and the consequences for prey selection.  Canadian Journal of Zoology 63:  2507-2515.

Barclay, R.  1989.  The effect of reproductive condition on the foraging behavior of female hoary bats , Lasiurus cinereus.  Behavioral Ecology and Sociobiology. 24: 31-37.

Jackson, H.  1961.  Mammals of Wisconsin.  The University of Wisconsin Press,  Madison, Wisconsin, USA.

Kurta, A.  1995.  Mammals of the Great Lakes Region.  Revised edition, The University of Michigan Press, Ann Arbor, Michigan, USA.

Tuttle, M.  1988.  America’s Neighborhood Bats. University of Texas Press, Austin, Texas, USA.

Schober W. and E. Grimmberger.  1997.  The Bats of Europe & North America.  T.F.H. Publications, Inc., Neptune, New Jersey, USA.

Shump, K.A., Jr. and A.U. Shump.  1982.  Lasiurus cinereus.  Mammalian Species 185:1-5.

Reference written by Anna Woehrle, Biol 378: Edited by Chris Yahnke. Page last updated 4-27-04.

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