Pallid Bat
A pale-colored bat with large ears, it can often be found living in human-made structures, which allow it to extend beyond its natural range.
About This Species
The pallid bat is a large, pale, long-eared bat, not easily confused with any other species.
Social behavior of pallid bats is quite interesting. There is a strong bond between mother and offspring, and the association may continue year after year. There is also strong group cohesion and roost site attachment. Young are provided preferential positions in roosts, pregnant females are attentive to other females in labor and females actually signal mothers whose young are in distress. Predators include hawks, kestrels, owls and snakes.
Living with Bats
There are 18 species of bat that call Colorado home. These amazing mammals are not only fantastic insect control, but are also valuable pollinators. Learn more about how humans and bats can live in harmony in our guide.
Bat Conservation
Bats remain one of the most mysterious land mammals, especially in Colorado, where 18 species spend at least part of the year. For example, the little brown bats in our state seem to hibernate differently than those on the east coast, and we are constantly learning about their whereabouts, habitats and behaviors. Our current research suggests that bat populations in Colorado are doing quite well.
One little brown bat can eat up to 18,000 small insects (like mosquitoes) each night. Their economic impact is estimated to be billions of dollars, and much of the agricultural industry relies on their insect control.
Beyond their economic impact, bats flaunt some impressive adaptations. They are the only mammal that truly flies, which requires a very unique anatomy. Their upside-down lifestyle requires adaptations in their “feet” to consistently grip. If people hanged upside down for even an hour, we’d lose consciousness; bats have developed amazing blood pressure accommodations to fit the lifestyle.
We are currently involved in a monitoring partnership called the North American Bat Monitoring Program (NA Bat). The program utilizes acoustic surveys to collect information on bat populations without interfering with their behaviors. We also are using PIT tags, like the chips put in household pets, to monitor a number of maternity sites. While data collection will take years, we’ve already learned new information about Colorado’s bat population, the most heartening of which is that the population appears larger and more widespread than we’d thought. This is an excellent start to learning more about the species, but we’ve got lots of problem-solving and technological innovation left to do.
Our priorities also include learning more about bats so that we are prepared for the potential spread of White-nose Syndrome. Finding and monitoring bats is crucial to this effort, but also comes with its own challenges. Because bats are small, flying mammals, much of the equipment used to track other species is too heavy for them. And during the winter, Colorado bats are very elusive, choosing to hibernate in small groups often in locations that are inaccessible to people.
More Information:
Physical Characteristics
Their eyes are large, and their face is covered with wart-like sebaceous glands. Color varies from pale creamy to light brown. Average measurements of 12 individuals from northwestern Colorado were: total length, 107 mm; forearm, 56 mm; and weight, 19 g. Wingspan is approximately 380 mm.
Range
The range of the pallid bat extends from southern British Columbia to central Mexico and east to central Kansas and Oklahoma. In Colorado this bat inhabits lower elevations of the Western Slope, broken rocky areas of the southeastern part of the state and along the foothills to Colorado Springs.
Habitat
This is a species of deserts and grasslands near rocky outcrops. The pallid bat's habit of using structures built by humans may allow it to extend beyond what would otherwise be its natural range. In Colorado, the pallid bat occupies semidesert scrub and pinyon-juniper woodlands to about 7,000 feet. Pallid bats are gregarious, although males may separate from breeding females in summer. Elsewhere, this species is not migratory and makes only short movements to hibernation sites.
Pallid bats probably hibernate in Colorado from mid-October to April, although there is no direct evidence of their winter habits here. Pallid bats form small colonies and use rock crevices, often in cliff faces, as day roosts. These roosts are selected for suitable temperature and protection from predators. Night roosts are also selected on the basis of a temperature that minimizes energy loss. Night roosts, such as crevices, shallow caves, overhangs, and man-made structures, are usually near day roosts. Both day and night roosts change seasonally as their thermal characteristics change.
Mortality is highest when young bats are first beginning to fly. Their habit of foraging on the ground makes pallid bats susceptible to injury and predation.
Diet
The pallid bat feeds principally on flightless ground-dwelling arthropods, such as crickets, grasshoppers, beetles, scorpions and spiders. Their presence is revealed by audible clicks as they forage after full dark and again before sunrise. Other foods include large moths, lizards, small bats and small rodents.
Reproduction
Copulation occurs between October and December, and sperm are stored by the females until spring, when ovulation, fertilization and implantation happen. Gestation is about 9 weeks. Older females generally give birth to two young, whereas younger females have only one. Young are born in June and July, and the sex ratio of the newborn is 1 to 1. Young begin to fly between 28 and 35 days old and are completely weaned at 6 to 8 weeks. Mothers forage with the young until the young become independent.