Relying on radio tags attached to four bats, Falxa made a startling discovery: Many of the more than 3,000 female adults and offspring fly to Capitol Lake each summer evening to feast all night on insects emerging from the lake.

Falxa, 49, was the first to verify the important role Capitol Lake plays in the foraging behavior of bats from the largest known bat maternity colony in Western Washington.

What was startling was the distance the bats fly each night. You see, all the bat research literature Falxa can get his hands on suggests that the one or two types of mouse-eared bats that reside at Woodard Bay travel only three or four miles from their roost to feed at night. The distance from Woodard Bay to Capitol Lake is about eight miles.

"That's a very long commute," Falxa said.

Falxa made the discovery about 12:15 a.m. July 13 on his fifth straight night of trying to locate a female bat he had radio-tagged earlier in the week. He would hear the bat leave the roost at dusk, heading in a southwesterly direction. Then he would lose her.

On the fifth night, he decided to check Priest Point Park. No luck. He motored over to Watershed Park. No luck. About to give up, he drove down to Deschutes Parkway near Percival Cove and started to hear the short, chirping signal on his hand-held radio.

"I was pretty excited," said Falxa, who lives in the Olympia area.

He returned the next night and saw large numbers of bats feeding over the lake.

"I presume they've been there a long time," he said.

That's right, said Janet Partlow, an Olympia native and longtime observer of bird and bat behavior around Capitol Lake.

Her own field trips to the lake have revealed large numbers of bats feeding there.

"The swallows feed there until dusk, and then the bats take over at night," she said.

Falxa and Partlow are both concerned about the possible toxic effects on bats if the Capitol Lake management committee decides to use chemicals this summer to kill the Eurasian milfoil that's choking the lake. No decision has been made on what to do with the milfoil, but the bats will be considered in the equation, noted state Department of General Administration senior planner Dave Schilperoort.

Partlow is less concerned about what would happen to the bats if the lake were restored to a free-flowing Deschutes River estuary.

"Mosquitoes breed in brackish water," she said. "The bats will go where the mosquitoes are, and the mosquitoes would use the estuary."

Falxa's bat tracking has also shown that the small ponds that dot South Bay supply the bats with places to get a drink of water and feed.

Close encounters

Having lived for years in South Bay, I've had a few interesting bat encounters of my own.

One of my most memorable wildlife observations occurred a few summers ago around a backyard campfire where my kids and I watched a female northern screech owl teach its newly fledged offspring how to hunt for bats.

The young owl, clumsy and unsure of flight, was no match for the dozen or so bats flitting through the night sky below the treetops.

I've chased plenty of bats out of my past three houses and even killed one once to have it tested for rabies after I found it hanging over my baby daughter's bedroom crib. She showed no signs of bites or scratches, but I wasn't taking any chances. The bat tested negative for rabies.

Bat myths

In fact, this is a good opportunity to refute a couple of bat myths.

First of all, very few bats are infected with rabies. Some studies suggest less than one-tenth of 1 percent are infected, according to Bats Northwest, a nonprofit bat conservation group.

Secondly, bats aren't blind. They often rely on echolocation to hunt their prey, but they can see.

It was an encounter with a bat that prompted Falxa to launch his Woodard Bay research. A couple of years ago he was walking through the woods near Priest Point Park when a bat flew by and scratched him on the head. At least he thinks that's what happened -- he never saw the bat.

Not taking any chances, he consulted his physician and opted for a rabies vaccination.

One of the side benefits was that the rabies vaccine made him eligible to handle bats, which is essential when you're trying to put a radio tag on a bat.

A phenomenon

As an avocation, he has conducted whale studies for Cascadia Research of Olympia and participated in a study of bat roosting behavior in 2001 in the Naches area of Eastern Washington.

Falxa, who has done his bat research with the help of volunteers but little outside money, will ask DNR for permission again this summer to radio-tag some Woodard Bay bats for further study.

"I think we have an obligation to at least investigate what's going on down at the lake," Falxa said. "It's a significant phenomenon."

One idea is that there are so many bats in the colony and so much wildlife habitat in South Sound has been lost to development that they may need to travel farther for food than they once did.

If allowed, Falxa will spend a month or so of sleepless nights this summer tracking bats while the rest of us sleep.

Bat fanciers are encouraged to contact Falxa with their own roosting and foraging observations at 360-561-0894 or roosts@batlab.org.

John Dodge is a senior reporter and Sunday columnist for The Olympian. He can be reached at 360-754-5444 or jdodge@olympia.gannett.com.