Bat                

Enter Sighting Bat Beaver Chipmunk CoyoteWhite-Tailed Deer Field Mouse Fox Fisher Groundhog Hare Opossum River Otter Cottontail Rabbit Racoon Skunk Gray Squirrel Snakes Vole

Introduction

The Little Brown Bat can fly, migrate, hibernate, sleep hanging upside-down, and find its way in the dark by echo location. A single bat can eat 500 mosquitoes in an hour. Little brown bat, like other bats, have developed a system of echolocation for evaluating the distance, size and movement of flying prey, and for evading obstacles. The ultrasonic calls are broadcast from the larynx through the mouth and echoes are reflected from objects back to the bat's ears. The ability to acoustically "see" objects is best demonstrated in total darkness of caves where little brown bat are able to fly about in close quarters with colliding. Echolocation functions with such a high degree of accuracy that the chance of a bat accidentally contacting a human in nature is negligible; the idea of bats attacking humans and becoming entangled in their hair is unfounded. Specializations in bats' ears permit reception of echoes with the least amount of interference from the high frequency calls being emitted. Partial separation of the bony capsule housing the middle and inner ear from the rest of the skull bones also reduces interference.

Food Habits

Little brown bats fill an important ecological niche, taking over the insect foraging activity of birds at night. Their food consists entirely of insects, mostly small beetles, moths and gnats, as well as mosquitoes. Quantities sufficient to maintain flight metabolism require these bats to eat up to half their weight in a night's foraging. Insect larger than those which can be consumed in flight are carried to perches where they are eaten at leisure. The most indigestible parts are dropped to the ground and are telltale signs of feeding perches. In late autumn fat is accumulated for the six to seven months of hibernation.

Family Life

In the summer, females form nursery colonies of various sizes, and males are usually solitary. Breeding takes place in late autumn, winter (in hibernacula) and early spring. The sperm remain dormant in the uterus until the single egg is released from the ovary. The egg is then fertilized in the right uterus. In approximately two months the young is born, sometime during May, June, or July. The naked newborn is one-fourth the weight of the mother. The eyes open on the second or third day. The young hold onto the mother's hair or nipples with claws and special hook-shaped temporary teeth. While females are foraging, they remain in the nursery colony; they can fly at two to three weeks of age, and by the fourth week they are weaned. At two months they are capable of breeding. Males are not sexually mature until the next year. Juveniles can be distinguished from adults by the elongated cartilaginous joints of the fingers.

Winter Habits

Hibernation and Migration. Because insects are not available as food during winter, temperate-zone bats survive by either migrating to warmer regions where insects are available, or by hibernating. Hibernation is a state of torpor (inactivity) during which normal metabolic activities are greatly reduced. Body temperature is reduced and heart-rate is slowed. A hibernating bat can thus survive on only a few grams of stored fat during the approximately five-to-six month hibernation period. Bats usually lose from ¼ to ½ their body weight during hibernation.

Threats

Bats rank as North America's most rapidly declining and endangered land mammals. The largest known cause of decline is exaggerated human fear and persecution.

Benefits

Most bats are valuable allies, well worth protecting. Worldwide, they are primary predators of vast numbers of insect pests that cost farmers and foresters billions of dollars annually and spread human disease. In the United States, little brown bats often eat mosquitoes and can catch up to 1,200 tiny insects in an hour. An average-sized colony of big brown bats can eat enough cucumber beetles to protect farmers from tens of millions of the beetle's rootworm larva each summer. Bats play key roles in keeping a wide variety of insect populations in balance.

Problems and Solutions

Most bats that wander into human living quarters enter through a loose-fitting door to the outside or an attic, an open window, an unscreened chimney, or a gap in an outside wall. They must have spaces at least 3/4-inch in diameter or 3/8 by 7/8 of an inch to enter. A room by room search will quickly reveal such possible entry points. Holes or crevices are easily plugged with steel wool or silicone calking. Chimneys can be covered with half-inch hardware cloth screening, and loose fitting doors may be fitted with draft guards. Unlike rodents, bats do not chew holes, so are easily excluded. Even when bat colonies cannot be excluded from walls or attics, they can be kept out of human living areas.