Office & Parks Winter Weather Closures
Due to expected extreme weather conditions, Denver Colorado Parks and Wildlife Headquarters (including the Call Center), Northeast Region and Littleton Offices, are closing at noon Friday, Nov. 8. Castlewood Canyon State Park is closed. Cherry Creek, Chatfield and Barr Lake Park visitor centers are closed.
Veteran's Day Office Closures
Colorado Parks and Wildlife offices, including park visitor centers, will be closed for the state holiday, Monday, Nov. 11.
Perhaps not the most creatively-named, this is the most common, and therefore one of the most important, bats in Colorado.
This is a large bat with medium-sized, rounded ears. The wings are long (325-350 mm) and powerful. Color is always some shade of brown, varying from russet to almost black and chocolate. This is the most commonly encountered bat in Colorado.
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.
Average measurements of 10 females from Fort Collins were: total length, 115 mm; forearm, 48 mm; and weight, 17 g.
The big brown bat is found widely in the New World, from Alaska to South America. It can be found throughout the United States in a variety of habitats. In Colorado it can be encountered just about everywhere, especially in towns and cities.
The big brown bat is more closely associated with humans and development than any bat in North America. It is often found in cities and towns and around structures. The big brown bat congregates in large groups in summer, and when these groups take up temporary residence in an attic, they can be both an annoyance and an effective control on flying insects. They also use rock crevices and trees for roosting. Temperature seems to be a factor in roost selection, females preferring higher temperatures than males.
Big brown bats are year-round residents of Colorado, hibernating in rock crevices, mines, caves, and a variety of other places. Prior to hibernation, they store up to 30 percent of their body weight in fat reserves. This bat has been studied widely for its remarkable homing ability. It can return to its roost site from distances of over 400 miles in less than a month, and returns of up to 40 miles in a single night are known.
Big brown bats are generalist insect feeders. They eat a variety of larger, flying insects and prefer beetles, even some too large for these bats to fly away with. Given their habit of living near humans, they are important in keeping urban insect populations under some control. Studies indicate that big brown bats eat many insects considered detrimental to humans.
When big brown bats emerge to forage in the evening, they make a strong, straight flight at a height of 20-30 feet above the ground. This flight is highly predictable, and the groups can be seen at the same location for weeks at a time. Foraging is generally in open areas, where they may work eight circuits while catching insects.
As with most Colorado bats, mating occurs in the fall, the sperm is stored over winter in the female's uterus and the young are born in midsummer, following a gestation of approximately two months. In the West, a single young per year is generally the rule; twins are common in the East. Females aggregate in maternity colonies of up to several hundred individuals.
Mothers apparently can recognize their own offspring even in masses of newborn bats. When young bats occasionally fall to the ground or floor, there is evidence that mothers recover them and put them back in the roost. Female big brown bats will move their young from one roost site to another if disturbed.
Predators include snakes, hawks, owls, weasels, raccoons, and domestic cats.
