Biologists Monitor CAVE Bats for White-Nose Syndrome

Bats, those insect-eating mammals we see at dusk as they flutter over our heads seeking their prey, have been battling white-nose syndrome (WNS) in North America since at least 2006. The organism responsible for this devasting disease is a cold-loving fungus named Pseudogymnoascus destructans. Bats are often infected with the fungus during hibernation – when the furry flying creatures are at their most vulnerable.

Photo at right, male cave myotis captured at Iron Pools. (WNPA 2019 Buecher-Northup Final Report)

Once infected with the fungal pathogen, bats frequently develop a fuzzy white growth on their muzzle, ears or wings – a characteristic feature of WNS. In addition to causing the white growth, the fungus can erode a bat’s skin and trigger atypical behavior, including abnormal daytime flight, in its bat victims. Many afflicted bats suffer severe emaciation and death as a result of depleted stored fat reserves.

P. destructans, which thrives in cold caves with high humidity, threatens the lives of millions of bats across the American Southwest and beyond. WNS has been detected in Texas and more than 30 other states. In 2019, the Western National Parks Association (WNPA) provided funding to a pair of bat biologists to monitor Carlsbad Caverns National Park (CAVE), located in southeastern New Mexico, for signs that the fungus might be spreading to CAVE bats.

Debbie C. Buecher, bat biologist and owner of Buecher Biological Consulting in Tucson, Arizona, has been studying caves for more than 50 years and the bat inhabitants of those caves for more than 35 years. As part of their WNPA project, Buecher and her research collaborator, University of New Mexico biology professor, Diana E. Northup, surveyed CAVE bats for the presence of P. destructans and signs of WNS.

View of pool at at Indian Shelter along Walnut Canyon where mist nets were deployed. (WNPA 2019 Buecher-Northup Final Report)

According to Buecher, 6 million bats have died from WNS already. That is six million fewer bats that would otherwise have eaten one half of their body weight in insects every evening. Buecher and Northup hope to reduce the spread of P. destructans through early detection of the pathogen.

A first goal of the project, surveying backcountry caves for bat hibernacula and bats from which to collect samples, was undertaken by park personnel from CAVE. Few hibernacula were located initially, but in late May of 2019, Buecher, Northup and their team netted and took samples from bats that emerged from a tunnel within Carlsbad Cavern. Five nights of successful netting recovered 51 bats of various species.

Captured bats were examined for signs of WNS. Samples to be tested for P. destructans were taken from a subset of the captured bats with Q-tip-like tools. Buecher and Northup, wore personal protective equipment (PPE) when handling the bats to avoid transferring any fungus or other pathogens among or between the animals. The researchers also removed parasites from the bats prior to releasing them on site.

“They were clean as a whistle when we released them,” said Buecher.

An added benefit of Buecher and Northup’s project was the robust program of citizen engagement at CAVE. For example, Buecher and Northup shared highlights of their work at public presentations. Park visitors were enthralled by two live bat “ambassadors” Beucher brought with her to these presentations – animals Buecher had rehabilitated but could not release to the wild.

Ultrasonic bat call recorded along Left Hand Tunnel that was acoustically identified as from a fringed myotis. (WNPA 2019 Buecher-Northup Final Report)

Another benefit of the research project was the establishment of a close, collaborative relationship among members of the research team and CAVE interpretative and resources staff. (rangers). Four or five rangers took notes and asked questions as Buecher and Northrup conducted their field work. Buecher and Northup also conducted a day-long workshop for the rangers on how to communicate science to the public.

Buecher and Northup met all planned objectives during their 2019 field and research work. As a result CAVE personnel, including interpretative rangers, have additional information about the park’s bats – information that will aid in monitoring the animals for WNS and will provide added value to interpretative resources rangers share with the public.

Fortunately, all tests for P. destructans performed on the CAVE bats were negative. For the time being, CAVE bats appear to have been spared the devastating impact of white nose syndrome.

Guest Contributor Susan E. Swanberg, Assistant Professor, University of Arizona

The remains of an ancient culture, including ruins of the Great Houses of Chaco Canyon, lie silently in a remote canyon on the Colorado Plateau in northwestern New Mexico. Now part of Chaco Culture National Historical Park, these massive and mysterious communal structures, made primarily of stone interlaced with mud mortar, speak of a long-ago Southwest culture. The great houses, once covered by timbered roofs and ceilings made from thousands of large pine beams, took nearly three centuries to build.

Photo at right, by comparing the age of timbers in the Great Houses to the age of trees from the upland areas and mountain ranges around Chaco Canyon, the scientists hope to determine the source of the Great House timbers.

Scientists have explored Chaco Canyon for more than 100 years, making it one of the best-known archaeological sites in the world. According to research scholar Stephen H. Lekson, “Its ruins represent a decisive time and place in the history of ‘Anasazi,’ or Ancestral Pueblo peoples.”* Who these ancestral peoples were and what they accomplished has been the subject of much study, including research sponsored by Western National Parks Association.

One of the pressing questions archaeologists face is how to place an ancient structure on a historical timeline. The rate of decay of radioactive substances is one way to determine the age of an object, but attempts using this method to date Chaco Canyon’s Great Houses produced vague results. Where ancient buildings incorporated wooden beams, like Chaco Canyon’s Great Houses, dendrochronology—the science of tree ring dating—can help us accurately place these structures in history.

Dendrochronology (from dendron, meaning “tree limb,” and khronos, meaning “time”) can be used to date wooden objects based upon an analysis of tree rings. A tree’s annual rings can be seen in a horizontally-cross-sectioned trunk; each ring is a layer of wood produced by a single year’s growth. By comparing tree ring patterns in a timber core sample to the patterns in known samples, researchers can calculate exactly what year the tree was cut down.

Dendrochronolgy was established as a science in the early 20th century by A.E. Douglass, an astronomer who founded the University of Arizona Laboratory of Tree-Ring Research. In 2014, University of Arizona scientists Thomas Swetnam, Jeffrey Dean, and Christopher Guiterman were awarded a grant from Western National Parks Association to study the source of timbers from the Great Houses of Chaco Canyon. By comparing the age of timbers in the Great Houses to the age of trees from the upland areas and mountain ranges around Chaco Canyon, the scientists hope to determine the source of the Great House timbers.

The knowledge gained from this study will contribute to our understanding of ancient Pueblo culture and enhance the experience of visitors to Chaco Culture National Historical Park.

*According to Lekson, “Anasazi is an archaeological term…for the ancient peoples of the Four Corners region in New Mexico, Colorado, Utah, and Arizona.” Many archaeologists and Native peoples prefer Ancestral Pueblo peoples.

By Susan Swanberg, assistant professor of journalism at the University of Arizona