英语语言学习：狗狗们的鼻子
Conservationists around the world are using a new tool in the field. It can navigate difficult terrain and detect the faintest chemical signals. It's also pretty good at a spontaneous game of catch. Turns out dogs are better at sniffing out wildlife than any human or machine. NPR's Adam Cole reports.
ADAM COLE, BYLINE: I met Dave Vesely for the first time in the middle of a soggy field. It was winter and it was Oregon, so of course it was raining.
DAVE VESELY: We've never been out here working in the rain before.
COLE: Vesely's here with a co-worker named Knife.
VESELY: He doesn't bark once we work.
COLE: Knife is an 11 month old Belgian sheepdog, jet black from nose to tail. He's here to learn. Not how to sit or stay, but how to find turtle nests. Western pond turtles are Oregon natives, but they're slowing disappearing as humans chip away at their habitat and foxes and raccoons gobble up their eggs. Vesely and his colleagues at the Oregon Wildlife Institute want to place small cages over the turtle nests to protect them from predators, but there's just one problem.
VESELY: Finding these turtles nests is really, really difficult to do it by eye.
COLE: After laying her eggs in a small hole, the mother turtle needs to gather dirt, brush and her own urine to plug the opening. Once the mud dries, it's almost impossible to see.
VESELY: And after just hours and hours of walking across fields looking for nests, it just occurred to me, you know, I've got a dog at home that could probably do this better than I can.
COLE: A few years ago, Vesely started training his dogs to zero on in a turtle's scent. Here in the grass field, he's hidden several cotton swabs. Some of them carry a few drops of water from a turtle aquarium, others have tap water. Vesely's newest recruit, Knife, has to find the scented swabs. I watch from the sidelines with Vesely's human co-worker, Jennifer Gervais and we have to squint against the rain and rising wind.
JENNIFER GERVAIS: Oh, a tree just fell down. Dog's going: Great big stick, I'm gonna go check it out.
COLE: But Vesely calls Knife back and the dog becomes more businesslike, weaving back and forth. He's searching for a scent bloom.
GERVAIS: If you've seen tobacco smoke drift on a breeze and how it curls and twists, and then imagine tracing that back to its source with your nose.
COLE: After a few minutes of frantic sniffing, Knife plops down on the ground.
GERVAIS: He's got something. Yes. So Dave's gonna play with him for a few minutes and let him know he's been a really good boy.
COLE: Around the world, dogs like Knife are helping conservationists track rare, endangered and invasive species. Their ability seems miraculous to us. Humans certainly couldn't find a few drops of water a turtle has touched in the middle of an Oregon rainstorm. But animal cognition expert Alexandra Horowitz says for dogs this kind of thing is no big deal.
ALEXANDRA HOROWITZ: The dog just has hundreds of millions more receptors lining the pathways of their nose than we do, and that probably means they have exponentially more ability to detect odors.
COLE: Horowitz studies dog cognition at Barnard College and she's collected some mind-boggling examples of canine olfaction.
HOROWITZ: So you have an Olympic size swimming pool full of water and then you have an identical pool full of water to which you add a teaspoon of sugar. They can detect the difference. That smells different to them.
COLE: The part of the dog's brain that processes this smell information is proportionally bigger than the part of our brain that processes sight. Horowitz says we humans tend to think of smells in binary - good or bad.
HOROWITZ: But for dogs, I think they really just are information.
COLE: Biologist Megan Parker has spent her career trying to get at that scent information. She says dogs are much more willing to share than other species with super noses.
MEGAN PARKER: Bears have a great sense of smell, but it would be really difficult to find a bear who wants to tell you consistently what it knows.
COLE: When Parker was a PhD student, she spent a lot of her time looking for African dog poop so she could collect DNA samples. The poop was really hard to find and Parker felt the sense of frustration that conservation biologists know well.
PARKER: The thing that they're looking for is the needle in the haystack or the needle on the moon.
COLE: Parker wondered if she could train her dog to help her find that needle, so she called up some people with experience training detection dogs: the police.
PARKER: And I'd say, hey, I'm a biologist and want to train my dog to find poop, and they would be - they would laugh.
COLE: Eventually, Parker did find someone willing to help her train her dog, and in 2000 she and a few like-minded biologists started Working Dogs for Conservation. Their dogs have teamed up with scientists around the world to find cheetah scat in Zambia, giant tortoises in Nevada, and an invasive snail in Hawaii.
And when Oregon biologist Dave Vesely was looking for scientifically rigorous ways to train his dogs for field work, he turned to the organization for guidance. I stopped by another one of Vesely's training sessions, this time under clear skies.
UNIDENTIFIED MAN #1: Good morning.
COLE: But his dog, Knife, wasn't there.
It turns out not every dog has the right personality for detection work.
VESELY: Knife had a lot of really early success and it's like right now he is just in the throes of his adolescent hormones.
COLE: Detection dogs need an incredible amount of drive and focus. Today, Vesely's brought along Sharpie, another young Belgian sheepdog.
VESELY: Sharpie's the B team. You know, I think she's going to work out really well.
COLE: He gives Sharpie a quick reminder whiff, turtle eggs shells he keeps in a jar.
VESELY: Search.
COLE: Sharpie weaves across the field, tail wagging, searching back and forth until suddenly she plops down in the grass.
VESELY: Good girl. Nice one for a beginner dog. Let's go find one more. That's good. Search.
(SOUNDBITE OF SONG)
UNIDENTIFIED MAN #2: (Singing) I'm a dog, I'm a working dog, I'm a hard working dog...
COLE: Adam Cole, NPR News.
