White-nose Syndrome
WNS Surveillance in Texas

WNS Surveillance in Texas


Texas is a state that is known for its many cave and karst resources and large bat colonies. Bat Conservation International (BCI) has been working closely with the Texas Parks and Wildlife Department (TPWD) since 2011 to monitor north Texas caves for the arrival of the fungus, P. destructans, and the disease it causes, White-nose Syndrome (WNS).

This ongoing research program surveys caves in the Texas Panhandle and its surroundings (including western Oklahoma) to carefully inspect bats for any field signs of the fungus or the disease. Biologists collect skin swab samples from individual bats and cave substrates and count the numbers of hibernating bats in each cave as part of the ongoing national WNS surveillance program and research on WNS and its spread and impact on hibernating bat species in North America. This work seeks to collect baseline survey data of hibernating bats and provide early detection of WNS at high priority locations in northern Texas.

 

During surveys conducted in January and February 2017, P. destructans was detected on three species of hibernating bats in six counties in Texas: Childress, Collingsworth, Cottle, Hardeman, King and Scurry Counties. The fungus was detected on three tri-colored bats, seven cave myotis and one Townsend’s big-eared bat. This is the first detection of the fungus on cave myotis and Townsend’s big-eared bats nationwide. The disease – bats sick from the fungus invading their skin tissues - has not yet been detected in these species.

White Nose Syndrome Survey CREDIT: Mylea Bayless

All data were collected in accordance to the guidelines outlined by the National Wildlife Health Center for Winter Hibernaculum Surveys and/or the sample protocol from the University of California Santa Cruz led study. White-nose Syndrome decontamination protocols were strictly followed between cave complexes according to the guidelines provided by the U.S. Fish and Wildlife Service.

 

Texas bat species at risk from WNS

Texas, with 32 bat species, has the greatest diversity of bat fauna in the country. Of these 32 bats, 14 species are known to occupy and use torpor in subterranean habitat (caves, mines, bunkers, culverts, etc.) in the winter months, making them potentially susceptible to WNS.





These species include:

† Indicates species listed as Endangered under the Endangered Species Act
* Indicates species confirmed for either WNS or P. destructans outside Texas
# Indicates species confirmed for P. destructans in Texas

 

What does this mean for our Mexican free-tailed bats?

A Mexican free-tailed bat captures an earworm moth
CREDIT: merlintuttle.org

What we have learned from studying WNS in bats over the past decade is that this disease most severely affects bat species that spend long periods hibernating to avoid cold winters. During hibernation, bats use torpor to save energy by lowering their body temperatures, heart rates, and respiratory rates. Immune function is also suppressed during torpor. When bats are torpid during hibernation, they are cold and inert and can’t fight off the fungus from invading their skin tissues. Some species may use torpor infrequently when there is a cold snap but can also be active and foraging during warm periods in winter. When bats are active, they can groom themselves and their immune systems work to fight infection. Mexican free-tailed bats, which roost in the millions at popular sites such as Bracken Cave, Austin’s Congress Avenue Bridge, and Old Tunnel State Park, do not hibernate for long durations during the winter, and are therefore unlikely to be severely affected by White-nose Syndrome.



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