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Hoary Bat (Lasiurus cinereus)

hoary bat


  • The hoary bat is the largest bat found in Alberta.
  • Adults may weigh up to 35 grams (1.2 ounces).
  • Wingspan can measure 40 centimetres (16 inches).


  • Long, narrow wings provide a strong, powerful, and rapid flight.
  • The body and inter femoral flight membranes are covered with thick dark brown or black hair.
  • Many of the individual hairs are tipped with white, giving a "frosted" or "hoary" appearance. The frosted coat may provide camouflage by making the bat look like lichen or a withered leaf on tree bark.
  • Hoary bats are distributed widely throughout North, South, and Central America and are one of the most widespread of mammals.
  • They are the only wild land mammal to naturally colonize the Hawaiian Islands.
  • They undertake long migrations in the spring and fall, as they raise their young throughout Canada and the northern United States but winter in the southern United States and Mexico.
  • Males apparently spend the summer in the western United States. Females migrate farther than males.
Natural History


  • Hoary bats are solitary individuals, roosting in areas of forest cover.
  • During the day, they are concealed among the leaves or on the bark three to four metres (10 to 12 feet) above the ground. One female in Wisconsin returned to the same spot on a spruce branch at least three years in a row.
  • Hoary bats appear to prefer evergreen trees, and could live throughout the boreal forest zone of Alberta.


  • Hoary bats leave the trees after dark to feed on nocturnal flying insects, often high above the canopy.
Reproduction and Growth

Breeding Behaviour

  • Most of the hoary bats found in Alberta are females or females with young.
  • Each female bears two young in late June.
  • The juveniles stay in the tree while the female forages for food.
Conservation and Management


The hoary bat is classified as Sensitive in the current General Status of Alberta Wild Species report. See:


  • Mortality at current and potential wind energy projects.


Page Information

Updated: Apr 29, 2009