Bat populations in Colorado may be headed for a decline that could cause ecological disruptions across the state.
Two bats discovered in Boulder County in late February 2024 were confirmed to have white-nose syndrome, a deadly fungal disease.
Additional bats in Larimer County also tested positive for white-nose syndrome early this spring.
The first North American bats with white fungus on their faces, ears, and wings were discovered in 2006 in caves where they hibernated near Albany, New York.
The fungus causes bats to lose nutrients and moisture through their skin and wake early from hibernation in search of food and water.
The disease spread west quickly, reaching Washington state in 2015, California four years later, and confirmed in Montana and New Mexico by 2021.
Evidence of the fungus was first reported in Colorado in the summer of 2022. White-nose syndrome is the result of infection by a fungus, Pseudogymnoascus destructans.
Most fungi thrive in warm, moist conditions, but Pseudogymnoascus destructans is a cold-loving fungus well-adapted to grow on bats during hibernation, when their body temperatures are lowered, and immune systems are suppressed.
The fungus affects bats’ fat reserves, critical for winter hibernation, and causes bats to awaken early in search of food. Since its discovery in North America, scientists have found the fungus in caves globally, where bats appear unaffected due to co-evolution.
Among the species most affected are Myotis bats, with some populations facing over 90% declines since 2006.
Colorado Parks and Wildlife have been testing for the fungus since 2019, and recent cases highlight the potential impact on Western Myotis species, with ongoing efforts to understand and mitigate spread through genetic analyses and conservation strategies.
