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Don't Disturb Bats
(Reprinted from "Caves of Mount St. Helens - Guidebook")
Bats use caves for both hibernation and raising young. Bats in this area are insectivores, feeding voraciously on flying insects all summer long, gradually building up a reserve of body fat which they will us to survive the winter while hibernating.
In the spring male and female bats segregate, with the females assembling in maternity colonies. In warm caves they give birth and share mutual body warmth to stimulate rapid growth of their babies. Only one maternity cave is known in Mount St. Helens area leading experts to believe they are rare and of great importance to survival of the species. A single disturbance of a maternity colony can cause abandonment of the site within 24 hours. This may result in death of the babies, and loss of one year's reproduction. If you see or suspect bats are using a cave as a maternity roost, leave the cave immediately and quietly, then report what you have found to the appropriate managing authorities before returning.
Bats are also sensitive to disturbance while hibernating. It may take a bat as much as 30 minutes to raise its metabolism enough to be able to fly. This slow reaction time has lead many cavers to believe they have not disturbed bats when in fact they have! When bats allow their body temperature to drop, and their metabolic rate to decrease, they go into a torpor. When in this state they remain alert to possible danger. If a passing caver is heard, or flashes a light in the direction of hibernating bats, the bats go into what can only be described as "slow panic." They will bum part of their winter fat to come out of hibernation and move to a "safer" location. Unfortunately, the "safer" location can actually be more dangerous because of potential freezing or excessive warmth (bats need a very selective range of temperatures to survive the winter). After several disturbances, so much fat may be used up that a bat will starve before the spring when insects are again available for food. If you encounter bats in a cave during the winter, leave the cave immediately. Bats only use the cave part of the year, so you can postpone your trip until the bats leave.
Historically, the Saint Helens caves are known to have sheltered six species of bats. Myotis evotis (long-eared myotis), M. lucifugus (little brown bat), M. volans (hairy-winged bat), M.yumanensis (Yuma myotis), Eptesicus fuscus (big brown bat), and Plecotus townsendii (big-eared bat). Several of the Myotis species are adapted to tree-dwelling as well as using caves. Unfortunately, the harvesting of timber near the mountain, before the land was set aside for a National Monument, has effected the population of these small bats. Therefore, visitors to the caves should treat all bats the same, by leaving them alone and undisturbed.
TOWNSEND'S BIG-EARED BAT (Plecotus townsendii)
(Reprinted from "Caves of Mount St. Helens - Guidebook")
This bat is the species of most concern, and teeters toward listing as an endangered species in the Cave Basalt area. It is, fortunately, one of the few animals in danger that both the cause of the problem and the management solution are understood. Disturbance of the bats in hibernation, and maternity colonies, is the problem and a reduction or elimination of that disturbance is the solution.
Population of this subspecies are declining throughout Washington. The decline seems related to caving pressure on hibernation and disturbance of maternity colonies. Quiet passage of a just a few cavers appears to be enough to cause arousal of the bats in the winter from hibernation. This causes a loss in body weight for Townsend's Big-eared Bat. Any unnecessary weight loss in a critical year may make the difference between death and survival.
Unfortunately this species appears to be sensitive during the summer months if the maternity colony is disturbed. Dead young were noted in Mt. Adams area caves following disturbance by cavers during the 1972 National Speleological Society Convention. To protect these bats in the Mt. St. Helens area, all cavers are asked to stay out of Bat Cave, Spider Cave, Dollar and a Dime Cave, Beaver Cave, and the upper end of Ole's Cave during the period from October to May. Utterstrom's and Powerline caves should not be visited (even just stopping at the entrance can be detrimental) from April until October.
Cave Closure List
(Reprinted from the Willamette Valley Grotto Web Site) - Updated November 2000
SOUTHWEST WASHINGTON CAVES THAT HAVE BATS AND OTHER SENSITIVE CAVE FAUNA
Mark Perkins, a cave biologist from Oregon, has studied the bats and other creatures in the lava tube caves of both Washington and Oregon. As a result of his research, he drew up a list of caves which have particularly sensitive bat colonies and other cave fauna and therefore should be avoided at certain times of the year to protect them. The following is an old list I had from him of some of the sensitive caves near Mt. St. Helens and Mt. Adams so, you can plan your trips accordingly. Since bats tend to move around due to disturbance by humans and other factors, you may find other caves with several bats in them.
If you spot several individual bats of the same or different species in a cave not listed below, please report it to Mark Perkins at: batsrus1@sisna.com and notify the rest of us through the regional list server so, we can add it to this list and avoid disturbing the bats in that particular cave during the winter hibernation period from October-March. Thanks.
-Larry McTigue
Caves to Avoid All Year
(Bat Nursery Sites from March-August/Winter Hibernation Sites October-March)
Mt. St. Helens
Mt. Adams/Trout Lake
- Christmas Tree Cave (gated)
- Poacher's Cave
- Big Cave -- Note: Don't confuse with Big Trench Cave, which is quite a ways east of Big Cave. But, Big Trench Cave is a bat hibernaculum and should be avoided from October-March but is ok to visit during the summer months. (See below.)
Wind River Ranger District between St. Helens and Trout Lake
Caves to Avoid in Winter
These caves should be avoided in winter between November 15 and April 15. Actual closure dates vary according to agency jurisdiction and weather.
Some, such as Pictograph, are closed from October 15 through May 1. By visiting the caves listed below only during the summer months you will be helping protect Townsend's big-eared bats and other bat species.
Charcoal Cave in Central Oregon is closed from April 15 to September 1 to protect the bat maternity colony.
Mt. St. Helens Cave Area
- Bat
- Beaver
- Blue Ribbon
- Breakdown Cave (per Kim Luper)
- Dollar and a Dime
- Little People's
- Ole's
- Prince Albert
- Spider
Mt. Adams Cave Area
- Back Bone
- Big Trench
- COG
- David's Den Annex
- Goose
- Ice Rink
- Ice Rink Annex
- Jug (east tube)
- Madison's Fence
- Poacher's
- Red Cave System
- Christmas Tree
Saddle Butte Cave Area
- Burns
- Coyote Trap
- Owyhee
- Rattlesnake #2
- Tire Tube
- Kitty Pooh II
- Kitty Pooh Extension
- Raven Pit
Central Oregon Cave Area
- Bat
- Bat Crack
- Charlie the Cave (lower passage)
- Deg
- Lava River
- Lee's
- Lower QMC
- Officer's
- Pictograph
- Stookey Ranch
- Wind
Western Oregon Cave Area
- Scott Mtn. Talus
- Blue River
- Mowich
- Grant's Park
- Fish Creek
How to build a bat House
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