Bad news for bats in the western United States: The fungus that causes the deadly white nose syndrome has been found on bats in five counties in north Texas, officials reported Thursday. Texas thus becomes the most recent addition to the list of 33 states to which the fungus has spread.
The fungus, Pseudogymnoascus destructans, is responsible for the deaths of at least six million bats in the Eastern U.S. since it was discovered in New York State in 2006.
Spreading readily among hibernating bats in caves and mines, the fungus causes bats to lose weight during hibernation season, forcing them to expend energy seeking insect prey that may be nonexistent during winter months. The disease also also causes serious dehydration in infected bats, which can often be seen licking snow and ice when they should be asleep in a cave. Bat colonies in the eastern states have declined by 90 percent or more within one or two years of being infected.
None of the fungus-contaminated bats found in Texas showed signs of being infected with white nose syndrome, named for the fungal growth that appears on sickened bats’ faces, ears and wings. That may not be good news, as bats can take two years after fungal exposure to develop the full-blown disease.
Texas is known for its immense bat populations, including the famed colonies of Mexican free-tailed bats inhabiting caves, as well as structures like the Ann Richards Bridge in Austin. Biologists note that the fungal epidemic seems to sicken only hibernating bats, likely being spread by direct contact between individual bats. As many Texas bats like the Mexican free-tailed don’t hibernate, they may escape the ravages of the disease. Bats that prefer to roost in trees or elsewhere outside of caves and mines may also escape the disease in its current form.
But other Texas bats species do hibernate in caves, including the cave myotis and Townsend’s big eared bat found exposed to the fungus in Cottle, Childress, Collingsworth, Hardeman, and Scurry counties north of Abilene. Hibernating bats often huddle in large, closely packed groups to conserve warmth, which almost certainly aids in the transmission of the fungus — as does most bats’ reduced immunity to disease during hibernation.
The Texas discoveries mark the first time the Townsend’s big eared bat, Corynorhinus townsendii townsendii, has been found to carry the fungus. Two of its sister subspecies within Corynorhinus townsendii — the Virginia long-eared bat and the Ozark big eared bat — are listed by the federal government as endangered species. Researchers have previously detected the fungus, but not the disease, in the Virginia long-eared bat. The shy and easily disturbed Townsend's, protected under California’s state Endangered Species Act, is suffering in part due to increasing human disruption of its habitat: the potential of a white nose syndrome outbreak is the last thing the species needs.
“The discovery of the white-nose fungus in Texas is a biological disaster and potentially an economic one, too,” said Mollie Matteson, a senior scientist with the Center for Biological Diversity. “With hundreds of caves, unique cave ecosystems and huge, world-famous colonies of bats, Texas stands to lose a rich natural heritage — plus the free pest control services of thousands of bats.”
Banner: Mexican free-tailed bats in an immense flock in Texas | Photo: iStock.com/derwood05