Important Updates:

The city has launched a beta to preview its new website and gather feedback. | More Info


The City of Boulder welcomes your feedback. Use our Inquire Boulder customer service tool to tell us what’s on your mind.

  • OSMP Trails & Recreation
  • OSMP Visitor Info
  • OSMP Get Involved
  • OSMP Nature & Restoration
  • OSMP - About
  • OSMP Kids & Families
  • OSMP Plans & Reports
  • OSMP en Español



The world's only flying mammals are right here in Boulder. They appear at dusk over ponds and waterways to drink and forage. Most people are entirely unaware of their presence, much less their benefits to the ecosystem. The rich ecosystems of OSMP are a great place to be a bat! The rock formations of the famous Flatirons create nooks and crannies that provide just the right combination of warmth and air flow into which the bats comfortably wedge themselves. Roughly 40 species of bats inhabit the United States, and 18 of those species live in Colorado.

Boulder County is home to 11 different species of bats, one-quarter of all the bat species present in the U.S. Along the foothills of the Rockies, we find the western edge of the range of eastern U.S. species of bats like the Red Bat. We also find the northern-most record in Colorado of the Brazilian Free-Tailed Bat. Although the Hoary Bat typically breeds farther north than Colorado, pregnant females have been observed. The diversity and richness of species here is magnificent and offers alert visitors a chance to observe bats around dusk as they flutter through the plains and canyons.

Powered by Mosquitoes

So, why are bats important?

  • They are significant predators of night-flying insects. A single little brown bat can catch 600 mosquitoes in just one hour. A colony of 150 big brown bats can protect local farmers from up to 18 million or more rootworms each summer. The 20 million Mexican free-tails from Bracken Cave, Texas eat 250 tons of insects nightly. A decline in bat populations increases the demand for chemical pesticides.

  • Our desert ecosystems would fail without bats. The bats pollinate the saguaro, organ pipe cactus and the agave. Many other plants and animals rely on these plants for food and shelter. If they were to die out, the entire desert ecosystem as we know it would collapse. Next time you slice a banana for your cereal or enjoy a mango, thank a bat. The wild stocks of these fruits are dependent upon bats for their pollination and seed dispersal. Dates, breadfruits, cashews and figs are also dependent on bats.

  • Bat guano is used as fertilizer and supports a bacteria that is used in detoxifying wastes, improving detergents, and producing gasohol, and antibiotics.

  • The vampire bat produces an anticoagulant that is more effective than any medical research has developed, and for this reason is being studied. Anticoagulants are important during operations and in the treatment of heart patients.

  • Bats' echolocation is a thousand times more sophisticated than any human produced sonar and is studied in the hopes of improving our technology.

Townsend's Big Eared Bat, which occurs in the Boulder area, is a sensitive species in need of immediate protection. Only eleven breeding colonies are known in Colorado; two of them are on OSMP.

Seasonal wildlife closures protect this and other species. Boulder's Open Space and Mountain Parks are home to an amazing variety of rare, threatened and imperiled species. 

Much More to Learn

We have been given a small glimpse into the habits and status of the bats that reside here. Much is yet to be accomplished. Little is known about the day and night roosting site usage, patterns of reproduction, location of maternity sites, overall distribution and hibernation. Nearly 40 percent of American bat species are in decline or listed as endangered. Bats are especially vulnerable to extinction, in part due to their low reproductive rate — the slowest reproducing mammals on earth for their size.

Volunteer Bat Monitors: What they do and why they do it!

The Volunteer Bat Monitoring Program began in 1995, in cooperation with The Colorado Bat Society, Boulder County Parks and Open Space, Colorado Parks and Wildlife, and Eldorado Canyon State Park. Members of the Colorado Bat Society did this survey work statewide, though the bulk of the information was gathered in Boulder County. The information gathered in Boulder is part of a network of research presented to the Western Bat Working Group, a collaboration of land managers and researchers focused on bat species in the Western United States.

Learn more about bat monitoring volunteers. The monitoring program provides great value to the department, the volunteers, and the bats. Volunteers monitor wildlife closures for two imperiled species, the Fringed Myotis and the Townsend's Big Eared Bat. Monitors also perform exit counts at known roost sites in the rock formations. Repeated yearly surveys at traditional sites provide us with trend information and possible warning signs of changes in activity. Seasonal closures of sensitive areas are the direct result of observation, monitoring and research. The Department has a good working relationship with climbing and hiking advocacy groups who help ensure that these closures are respected. The cooperation of the public and work of volunteer monitors helps us to protect the bats while they are rearing their babies, known as pups.

Bats are fascinating creatures, all the more so because they are not easily observed. Volunteers in this program, many of whom return year after year, turn their curiosity into an opportunity to learn more about and appreciate these unique and fascinating mammals.