Western Pipistrelle

Bats are mammals, and members of the order Chiroptera. They are the second largest order of mammals in number of species.

Western pipistrelles sometimes leave their roosts before sundown, and can be mistaken for late-flying butterflies, because they are so tiny and fly slowly and erratically, with much fluttering of their wings. Most common at low elevations in desert scrub and arid grassland habitats, they are also found in adjacent woodlands. Although they range over the arid West, western pipistrelles require a ready source of water—a lake, stream, or even a swimming pool. They—and some shrews—are the smallest mammals in North America, with weights ranging from 2—6 g. In spite of their tiny size, western pipistrelles usually give birth to twins, which are born and raised in small maternity colonies. The largest colony yet found comprised just four female bats and their eight young.

A small, drab-gray or smoke-gray bat with distinct, black, leathery facial mask and black membranes; tragus short, blunt, and slightly curved; underparts pale smoke-gray.

Habits: This bat is associated chiefly with rocky situations along watercourses. Its daytime retreat is in the cracks and crevices of canyon walls or cliffs, under loose rocks, or in caves.These are among the most diurnal of bats, beginning their foraging flights very early in the evening and often remaining active throughout the early morning hours. Pipistrelles are slow bats and may be distinguished on the wing by their slow, fluttery flight which is restricted to small foraging circuits. Occasionally, individual bats have been observed on the wing during mid-day, during which time they water to alleviate stress caused by the arid environment they inhabit.

Life Cycle: Like many other species of North American bats, The Eastern Pipistrelle breeds in the fall, and 1 – 2 young are born the following late May or early June. For the first few days after their birth, the young are carried by the female as she forages. They are capable of flight in about three weeks after birth and are soon capable of foraging on their own.

The Eastern Pipistrelle hibernates in the northern parts of its range, but remains active throughout the year in the South. It roosts in caves, rock crevices, old mines, hollow trees, buildings, or clumps of Spanish Moss. It forages for flying insects in an erratic, fluttering flight along forest edges, over forest canopy, or over bodies of water. The Eastern Pipistrelle roosts singly during the warm months, but may congregate by the hundreds in winter hibernacula. Males may live 15 years, but females seldom reach 10 years of age.

Damage: Many bats prefer open cavities such as house attics for nursery colony sites. These cavities protect the bats from predators, and offer the warmth that allows the newborn bats to use their energy for rapid growth. Large colonies can deposit sizable piles of droppings (guano) which can cause a strong, musty odor and stain ceilings and walls. In addition,bats can be noisy because of scrambling and squeaking.Bats do not chew entrances but can get into buildings through any existing openings 1/4 in. (5 mm) in diameter or larger.Bats may also get into rooms through open doors and windows, loose or torn screens, or gaps around attic doors.

These bats are often lost youngsters just developing their flying skills. A bat flying around in a room may appear to be diving at people. In fact, it is merely swooping downward to regain flight speed and control which were lost when it slowed to make the turn at the end of the room.Opening an outside door, or window and screen, will allow the bat to exit. However, if it lands, a jar or other container can be placed over the bat and a piece of heavy paper or cardboard slid under the mouth of the container, trapping the bat inside. The bat can then be released outside away from children and pets. Never attempt to touch bats with your bare hands.

Control: The first step in controlling bat-human conflicts is to determine what animals are causing the problem.Scratching, squeaking noises in walls, attics or chimneys can be caused by bats, birds, mice, squirrels, or raccoons. All of these animals may use human dwellings for refuge at some time if the opportunity presents itself. About half of Utah’s bat species enter and use human dwellings. Bats may occupy dwellings for an entire season, or briefly during spring or fall migrations.Evidence of bat activity may first appear as a brown stain on the ceiling or walls of a dwelling, and an accompanying musty, urine-like odor. The homeowner may also want to check for leaks in the roof which can cause similar stains. If the attic or crawl space can be examined, live bats may be observed flying or roosting on the walls or beams. If no bats are present, the area should be examined for droppings.

Roosting bats tend to gather in clusters near the roof peaks causing their guano to collect in piles beneath these high points. Guano may also be found clinging to the rafters and roof beams. Rodent droppings will not be in piles or on rafters, and will occur more commonly along the base of walls. In addition, bat droppings are solid brown and666 crumble easily because they contain insect fragments. Rodent droppings contain plant fiber and do not crush easily. Several types of small arthropod insects are commonly found with large colonies of bats in buildings. Some of these insects live on the bats themselves, while others feed on the guano. These bat ectoparasites rarely bite humans or pets, and do not cause diseases. Without bats or guano,the insects simply die.