Eastern Pipistrelle (Pipistrellus subflavus)

Photograph of the Eastern Pipistrelle

TPWD ©

Protection Status Notes
P. subflavus is solitary except for small nursery groups and is not listed by the U.S. Fish and Wildlife Service.
Description
Pipistrellus subflavus is a small yellowish-brown insectivorous bat pip on a matchbox.. yes, they are that small.which is easily identified by its tri-colored fur (black at the base, followed by a band of lighter brown, and dark tips) and the juxtaposition of its black wing membrane surrounding a reddish-orange forearm. The eastern pipistrelle has short round ears with a blunt, straight tragus. It can often be identified when hibernating by its distinctive orange forearm. It has a forearm length of 31-35 mm and weighs 4-8 g.
Life History
The Eastern Pipistrelle is one of the first bats to enter hibernation, typically in September or October, and one of the last to emerge in the spring. Mating occurs in autumn before hibernation, and in some cases again in the spring. Females store sperm over winter and ovulate when they become active in April or early May. They give birth from late May to mid July, after approximately a 44-day gestation period, usually to twins. Each pup weighs approximately 1.6 g (both pups together weighing nearly 50 percent of the mother's after-birth body weight). Pups, which are born blind and hairless, are capable of flight in about three weeks and are completely weaned by the fourth week. Eastern pipistrelles live up to 14 years in the wild. Highest mortality appears to occur in the first or second hibernation periods, usually due to failure to store large enough fat reserves for the first winter.

The eastern pipistrelle performs short annual migrations between winter hibernation and summer nursery sites. Such travel is not known to exceed 50 miles and averages 31 miles or less. These bats often swarm at cave or mine entrances before entering hibernation.

The eastern pipistrelle is one of the first species to emerge each evening, usually having two foraging bouts per night, one beginning soon after sunset and another around midnight. This bat has an erratic, fluttery flight pattern while foraging, and can attain a flight speed of 11.6 miles per hour in the open. The eastern pipistrelle can catch prey at a rate of one insect every two seconds, increasing its body mass as much as 25 percent in just thirty minutes.
Habitat
Eastern pipistrelles spend six to nine months per year hibernating in caves or mines, mostly at ambient temperatures of 46.4-55.4° F (8-13° C). They typically hibernate singly on cave walls or ceilings where there is minimal airflow. Relatively stable conditions are preferred, enabling the bats to arouse infrequently. These bats are loyal to their hibernation sites and may return to the same cave or mine every winter of their lives. During summer, the sexes live separately; males are often solitary while females form small maternity colonies of 35 individuals or less in buildings, tree cavities, and rock crevices.

The eastern pipistrelle forages along forest edges and over ponds and waterways for small insects, such as leafhoppers, ground beetles, flies, small moths, and flying ants.
Distribution
The Eastern Pipistrelle is distributed throughout the eastern United States, ranging as far west as Nebraska, Kansas, Oklahoma, and Texas, and from southern Canada south to Honduras.

They can be found in the eastern half of Texas including the Rolling Plains west to Armstrong County and central Texas as far west as Val Verde County, and a recent record from Lubbock County.
Threats and Reasons for Decline
Like other cave-dwelling species, the eastern pipistrelle is often disturbed or killed in its hibernation caves. The impact of forestry practices on summer habitat remains uninvestigated.
Ongoing Recovery
Bat-friendly gates can prevent human disturbance of hibernation sites. Better knowledge of summer habitat requirements is a prerequisite to further management.
Other
Little is known about Eastern Pipistrelle summer roosting and feeding habitat requirements.
For more information
  • Refer to the online version of The Mammals of Texas for additional details on the Eastern Pipistrelle.

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