Bats are proving to be abundant in the Tulelake Basin.
There’s Tulelake’s Batkid and, now, record numbers of bats at bat caves at Lava Beds National Monument.
A week-long survey of 77 of Lava Bed’s 700-plus hibernacula, or caves, resulted in finding 1,582 endangered Townsend’s big-eared bats, seven Myotis bats, one big brown bat and an unidentified bat. In previous years, the annual surveys have located 1,250 to 1,450 bats.
Hibernacula is the term used for places where bats hibernate. Lava Beds biologist Katrina Smith said undisturbed caves provide the best habitat for hibernating caves during the winter when food sources, mostly insects, are not available.
Thirteen people — 10 from the park and one each from Bat Conservation International, Modoc National Forest and U.S. Fish & Wildlife Service — conducted the count.
“It appears Townsend’s big-eared bat populations continue to be stable and may even be increasing,” Smith said. “This is great news as this species is in decline elsewhere due to loss of habitat and increased human disturbance. It is also important since healthy bat populations keep insect populations at bay, reducing risk to crops and nuisance to humans.”
She said Townsend’s hibernate both alone and in clusters. They use their ears for thermoregulation to keep their bodies at the necessary temperature. Some bats tuck their ears underneath their wings to stay warm while others extend their ears to cool off. Smith said the largest cluster found this year had 30 bats.
“It seems the bats are moving into deeper, colder caves,” she said, referring to this winter’s unusually mild temperatures and lack of snowfall. “There may be a connection between this behavior and the warm winter weather. One of the cold, deep caves that usually contains 50 to 100 bats had more than 400” during this year’s survey.
“We’re getting better at finding bats,” Smith said. “They definitely move around during the winter time.”
Again, no sign of white-nose syndrome was found. The fungal disease has killed millions of bats in the Eastern U.S. and Canada and is mostly confined east of the Mississippi River, although Smith said the disease has now been found in Minnesota. For the past few years, Lava Beds has required visitors to participate in a white-nose syndrome screening process before entering any park cave.
Smith said “stratified random sampling protocol” was again used by researchers. Under the protocol, teams annually visit caves with historic populations of 30 or more bats, caves with five or more, caves with smaller populations and caves not previously surveyed. In the past five years, three new hibernacula averaging more than 30 bats were discovered using the survey method.
“With more than 700 caves, it could be many years before all caves are searched during the winter season,” Smith said. “There’s a lot of caves we haven’t seen yet. The possibilities abound for finding more hibernating bats.”