When people at Sisters Elementary School called me in the fall of 2005 about a bat in one of the classrooms, it reminded me of how easily bats can find summer homes in human buildings, and the excitement they often cause doing so.
Thanks to horror films, bats have been given a bum rap. Truth be known, bats are our best control for the spread of West Nile Virus and malaria. Bats, especially Myotis bats—the kind that was in the elementary school—eat mosquitoes by the tons, literally.
When the workers who built the Panama Canal returned to their homes in Texas, many were malaria-carriers, having been bitten for their blood by female mosquitoes carrying malaria. As a result, Central Texas became a horrifying place to live due to the spread of malaria. On the banks of the Guadalupe River stands a "bat tower," the legacy of Dr. Charles Campbell, who had it built in 1918, one of thousands that would be erected in Texas, Florida, Arizona, and as far west as California.
Campbell had a brilliant idea for controlling the spread of malaria and eliminating it from the state: using bats to eat mosquitoes. He sent teams of men across the border to collect thousands of Mexican free-tailed bats with which they seeded the towers.
Campbell not only succeeded in eliminating malaria from Texas, but also became a millionaire selling the bat guano collected from beneath his towers. In 1925, he went on to write a book about the project: "Bats, Mosquitoes and Dollars."
Closing Local Caves for Bats
The Deschutes National Forest, in an effort to protect bat habitat, has taken on the thankless task of closing a few of the lava tubes south of Bend. If there's one thing that stirs up some people, it's not being allowed to access public land.
Unfortunately, people with a bad attitude about the closures don't seem to consider that, like you and me, bats have to have a home, too. When winter sets in, we just put on more clothes, stoke up the fire or turn up the thermostat. Bats, in this part of the U.S., have to go into a death-like sleep/torpor and wait out the winter, and one of the safest places for them to spend winter is in the lava tubes around Bend.
The humidity and temperature of most lava tubes is constant all winter. Temperatures range from 45 to 49 degrees, and the air temperature never drops to freezing on the dry ceiling where bats hibernate.
The exceptions are ice caves, like South Ice Cave. I found three Townsend's big-eared bats in a wet area of the cave one winter (I think they were forced into the cave to hibernate by a sudden cold snap). They were hanging from the ceiling of the cave, covered with ice crystals and barely alive, and probably never made it to spring. On the floor of the cave, I found a dead bat half frozen in ice and covered with mold.
I began working with the bats back in the early '50s, when my caving partner Phil Coyner and I began exploring and mapping the lava tubes southeast of Bend. In addition to the long-eared variety, we also met up with big brown bats and at least three species of Myotis, known collectively (but not scientifically) as little brown bats.
Boyd Cave had a population of about 50 Townsend's long-eared bats sleeping away the winter, with a few Myotis and big brown bats mixed in. In the '70s I banded several Townsend's bats in Boyd Cave. One returned 11 years in a row to almost the same spot on the ceiling. However, some miscreant shot it during the 11th year—a senseless act of vandalism.
Skeleton and Wind Caves are also populated in winter with hundreds of bats. As the popularity of "caving" grew, so did the bat population decrease. In Bat, Stookey Ranch and Stout Caves, the population dropped so dramatically biologists placed gates at the openings to save the bats.
Since gates have been installed, the bat population has steadily increased in one cave from 200 to 325. That's what the closure signs are all about: protecting bats, not stopping people from recreating.
Skeleton and Wind Caves are also populated in winter with hundreds of bats. As the popularity of "caving" grew, so did the bat population decrease. In Bat, Stookey Ranch and Stout Caves, the population dropped so dramatically biologists placed gates at the openings to save the bats.tweet this
In these days of environmental enlightenment, I find the actions of people responsible for vandalism particularly disappointing and downright infuriating. You'd think anyone who enjoys going out to explore the beauty and solitude of our lava tubes would respect the nature of the countryside. Unfortunately, that's not always the case.
In addition to a safe spot to hibernate, known as a "hibernaculum," mother bats also must have a sheltered place to stash their little ones when they're out snatching up insects at night.
When I was banding bats with Oregon Museum of Science and Industry science students, we got the job done quickly so as not to disturb the bats' deep sleep. It was during those times of banding that we watched an occasional bat flying about, or one or two awake, sending out their sonar-like signals as we moved beneath their roost.
Female bats have the capability of storing sperm and even arresting development of their babies until conditions are suitable to feed the tiny pups. A bat hibernating is close to death; all its energy must be channeled for survival. Their heartbeat and respiration drops to almost zero, and when the oxygen content of the blood reaches a dangerous low they must wake up, fly about the lava tube and then go back into a deep sleep.
If you visit one of your favorite caves and find it's closed, respect the closure. The bats sheltering in the cave have enough problems from habitat loss and chemically poisoned prey without being pestered while trying to sleep. Please leave them alone and give them every break they need to survive.