Ask a biologist what's the least understood of all the mammals. Chances are the answer will be … bats. The Northwest is home to at least 15 species, only one of which has a call that's audible to the human ear.
High tech gizmos are shining more light on the secret life of the region's bats. Correspondent Tom Banse takes us on a nighttime fieldtrip.
| Spotted bat|
It sounds like crickets or something.
Sound: [rapid clicks of spotted bat calls]
But what you're hearing is perhaps the rarest of Northwest bats. This is the spotted bat hunting for moths to eat. It has a wingspan of more than a foot and huge pink ears.
More sound: [feeding call]
A biologist recorded these sounds below the basalt cliffs of Moses Coulee in north central Washington. The arid gorge is a hotspot for bats in the Northwest.
The Nature Conservancy's Chuck Warner says it's a good place to investigate basic questions that we still don't know the answers to here in 2007. Like how many bats do we have? Where do they go for the winter? Are they doing well or poorly?
Chuck Warner: “One of the reasons they're important is because we don't know how important they are. You know, we don't want to jeopardize something or lose it before we find out what kind of value it can hold — not only economically, but intrinsically, biologically.”
Warner says the secretive bats probably consume large quantities of pest insects. We can't observe that first hand because the critters are active in the dark. Plus they're up in the air where we don't go. And they make sounds we can't hear, except for that spotted bat.
Chuck Warner: “They're a hard animal to study. But the technology is just now coming to a point where there's going to be a huge turnabout in the amount of information and data that we can gather.”
Sound: [Bat detector chirps]
The technology starts with the bat detector, a handheld recorder that can shift the frequency of bat calls into the audible range.
|Sonogram shows the distinctive signature of a small footed myotis bat|
Katy Warner: “That was a very faint bat call on the detector, that clicking sound.”
Later at the field station, wildlife biologist Katy Warner uploads recordings into some specialized software. It has the catchy name, Sonobat.
Katy Warner: “It's pretty hard to do the identification in the field. You pretty much need to bring the calls back and look at them with the Sonobat software.”
The software slows the bat calls way down for analysis.
Katy Warner: “This is a western pipistrelle….”
Sound: [time-expanded western pipistrelle calls]
Katy Warner: “Let me find a spotted bat so we can hear the difference.”
Sound: [time-expanded spotted bat calls]
Katy Warner: “It's very different than real life. And the time expanded spotted bat call sounds much different than the call of a western pipistrelle.”
A Humboldt State University professor has won federal funding to enhance the software. The northern California prof wants to create an automated voice recognition system for bats.
Sound [fade up rich nighttime coulee ambience/cicadas]
Still, there's a place for old-fashioned fieldwork. On a moonless, September night, twenty Nature Conservancy volunteers and staff are strung out in a long line down Moses Coulee.
Margaret Amara of Moses Lake, Washington is counting spotted bat calls while her husband logs the activity patterns by flashlight.
Margaret Amara: “I was worried that you would have to look at them and they would come flying at you. They said, no it's all by sound. I go, I can do that. Yeah, I wasn't real fond of bats, but now I have a new thinking about bats. They're pretty amazing what they do.”
One area of emerging concern: the burgeoning number of wind farms in the Northwest. The past two summers, a study outside Lakeview, Oregon investigated whether high frequency loudspeaker broadcasts could deter bats from potential danger.