Bats in Trouble
(This 975th Buffalo Sunday News column was first published on November 29, 2009.)
Little Brown Bats with white nose syndrome
photo by Nancy Heaslip, New York Department of Environmental Conservation
Bats have been in the news lately for two reasons, the first so bad for the little night fliers that extinction of some species is a possibility. Bad for us as well, because bats are famous insect eaters. Their decline could mean an increase in crop-damaging insects affecting our food supply.
First, many bats have been killed by an as yet unknown pathogen associated with a fungal growth around their faces. This fungus has given the disease the name white nose syndrome. First identified in a cave roost near Albany in February 2006 and subsequently in many caves and mines throughout the Northeast, the disease is fatal to about 95% of the bats affected and has killed tens of thousands. Because this disease may be spread by humans, many bat caves are being closed to spelunkers. An excellent summary of what we know about this problem is to be found in a presentation by state DEC bat expert Al Hicks.
Second, a number of bats have been killed by wind turbines. I am one of those who believes that windmills are not, as some friends believe, bird Cuisenarts; the number of bird fatalities is quite small relative to their population. On the other hand, the proportion of bats killed may be significant.
Apparently bats detect the motion of the windmill blades with their internal radar. Approaching the turbine blades, they are killed, not by being hit, but by the vacuum created by the extremely fast blade motion. (Blade tips move at up to 200 miles per hour.) The vacuum causes severe injuries to the bats' respiratory systems - an effect formally called barotrauma. These injuries cause blood to fill the little mammals' lungs, effectively drowning them.
Bat Caves in New York State
We only have two known caves where bats hibernate in western New York so most of our local bats either migrate or overwinter in man-made structures. Cave hibernators have been most subject to white nose syndrome, migrants to wind turbines.
As is so often the case when new problems like these arise, we need to gather data about their overall effect on the population of these flying mammals. In the case of the cave bats, the evidence of major loss seems clear, but it is not even known whether other bats are subject to the disease and whether wind turbine losses are also critical.
To gather this needed evidence about bat populations, Carl Herzog, biologist for the Department of Environmental Conservation in Albany, initiated a statewide series of surveys this year. And so one night last June as one of the 49 project teams, Chuck Rosenburg, Mike Galas and I slowly drove a designated 20-mile route along roads running south from East Aurora. We had an acoustic receiver on our car roof connected to a computer inside.
To us this was an interesting, even at times exciting, experience. The computer screen glowed with a horizontal line like a heart-monitoring oscilloscope. But in this case the sudden blips registered approaching bats instead of heartbeats. Sometimes we could even hear the ticks the bats emitted for echolocation.
Because I rarely see bats, I was amazed at the number we recorded. Our evidence is still being analyzed in Albany but I suspect that we heard at least one hundred.
This is the first year of this project so the data will serve as a baseline for comparison in subsequent years. Herzog has, however, shared with me some of his observations about this year when about 500 mostly volunteer staff-hours produced over 4000 bat recordings. Two species are of special interest.
The chance, Herzog says, of detecting the cave-dwelling "little brown bats currently increases with distance from Albany. There are few known hibernation caves or mines west of Syracuse, so the farther west the more likely the local summer bats hibernate outside of the state. Pennsylvania, for example, has literally thousands of caves and mines."
"All we can say about big brown bats is that they are still abundant and have not suffered the dramatic decline that other species have. Perhaps their eschewing the damp, underground sites favored by other species is conferring some protective benefit for them. Another possibility is that being more widely scattered is a better survival strategy when faced with a communicable disease."
Next year's counts should shed more light on the fate of these remarkable animals. Stay tuned.-- Gerry Rising