Bat study seeks out roosts

BEND, Ore. — In her eight years catching bats, Nadja Schmidt has learned lessons about them.

First, they are fragile. Second, they should not be feared.

“A lot of pictures make them look scary,” she said. “But they eat mosquitoes. They don’t bite that hard, except for the big ones.”

Schmidt, a wildlife technician with the U.S. Forest Service, was among a team of bat catchers hat trekked out into the High Desert east of Bend on a recent Monday night. The mission was part of a two-year Bureau of Land Management project trying to determine where western long-eared myotis bats go during the daytime, said Christopher “Digger” Anthony, wildlife biologist with the BLM in Prineville.

“The main thing is to identify their roosts,” said Anthony, who is leading the research as part of his master graduate studies with Oregon State University in Corvallis. Figuring out where the bats go during the day will fill in gaps in knowledge about what habitats are most important for the flying mammals.

A 2007 study determined there were nine species of bat frequenting the playas — seasonal shallow lakes — south of U.S. Highway 20 between Brothers and Hampton. The western long-eared myotis proved the most common. The small bats, which have a wingspan of 10 to 12 inches and weigh 0.2 to 0.3 ounces, are shrouded in mystery, including where they go in the winter.

For now, the focus is figuring out where the bats roost on summer days, whether they prefer places such as rocks, living junipers, snags or burned-out logs. Juniper-thinning projects are underway near Frederick Butte, in part to help sage grouse by promoting sage brush habitat, so Anthony wants to know if those are affecting the bats.

The study also hopes to determine whether male and female bats have different roost preferences.

Last year, Anthony’s team caught and affixed transmitters to 15 bats — eight males and seven females. This year he hopes to track 17 more bats.

Scientists depend on the tiny transmitters, attached to bats’ backs with surgical cement glue, to figure out where the bats go during the day. But before Anthony and his crew could attach the transmitters, they had to capture the bats. Catching bats requires nets, calm winds and some patience.

At dusk, the bat catchers stretched out mist nets — fine mesh nets strung between two poles like a volleyball net — over a playa near the base of Frederick Butte, about a 20-mile drive from Brothers. As it grew dark, the bats began to bounce around the watering hole but were dodging the nets.

Winds probably were the problem. Bats notice the nets more when they move in the wind, said Lisa Clark, BLM spokeswoman in Prineville, who was also part of the bat-catching team.

“They can see it as a barrier and avoid it,” she said, noting that the bats “see” something using echolocation.

After a change to a less windy part of the playa for one of the nets, bats started to fly into the trap. Wearing blue rubber gloves, Cassandra Hummel, another BLM wildlife biologist, untangled a bat from the net. Then, she tucked it into a brown paper bag and put the bag in the pocket of her waders.

Bagging and pocketing bats does three things: keep them from flying off, keep them warm and keep them separated to avoid spreading illness among the bats. Bat researchers are particularly concerned about white-nose syndrome, prevalent in the northeast part of the U.S., spreading west. So far, there have not been cases of the disease, a skin infection caused by a white fungus, in Oregon.

Brought to the tailgate of a pickup, which serves as an outdoor lab table, the bats caught Monday night were identified, weighed and measured. While some bats tried to wiggle free while being examined, most calmed down when held snuggly.

Living up to their name, the bats have long ears.

Anthony glued transmitters on some of the bats after snipping away a patch of their fur using nail scissors. About the size of half of an AAA battery, the transmitters have a 5 1/2 -inch wire antenna, which dangles from the back of the bat. Members of the bat-catching team said the transmitters do not affect the bats’ flight. Anthony said the transmitters run for about 12 days, which is also about how long it is until the glue gives way and the device falls off the animal.

“So you have a really short window to collect as much data as you can,” he said.

The glue takes 10 minutes to dry, so once a transmitter is on a bat, Hummel wraps the animal in nylon and then folds it into a washcloth, hoping to keep its body temperature up.

“We call it a little bat burrito,” Hummel said. Active bats often have a body temperature around 102 degrees. If they cool down, they can quickly become lethargic. When this happened to bats, she would put a hand warmer next to them. Soon the bat would be warmed up and take flight, seemingly not bothered by the hardware glued to its back.

A day crew comes out at 7 a.m. the morning after the bats were captured. Using radio gear, they locate the bats, pinpointing where they are and what they have chosen for a roost.

“We are try to get visuals on the bats in the roosts,” Anthony said.

Despite the winds around sundown, Monday night turned about to be a good time to catch bats — the team caught eight in all. The end of a hot day often is a good time to catch bats, Anthony said. It is when bugs may swarm. Rain and cool weather keeps insects from buzzing around, which also keeps the bats from flying.

“They are not going to waste energy,” he said. “If there is not a food source out they won’t be out.”