In Fla., Scientists Use Magnets To Disorient Crocs

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MELISSA BLOCK, host:

From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.

ROBERT SIEGEL, host:

And I'm Robert Siegel.

Now, some news you can use the next time you have to release a crocodile in the wild in the hopes that it won't come back to where you found it. That's not an everyday problem for most of us, but in Florida, sometimes, a crocodile crawls into someone's yard, and sometimes, the croc is placed back in the wild.

The crocs are evidently a very gifted species when it comes to getting right back to that same yard after they've been taken away. So here is the latest experimental tool to keep them from doing that: magnets.

Lindsey Hord, a biologist with the Florida Fish and Wildlife Conservation Commission, joins us from his office in Okeechobee, Florida.

Lindsey Hord, what do you do with magnets?

Mr. LINDSEY HORD (Biologist, Florida Fish and Wildlife Conservation Commission): We're attempting to disorient the crocodile's navigational senses and prevent it from returning to its capture site by placing magnets on a crocodile's head while it's in transit from its capture site to its release site. Of course, then we remove the magnets at its release site. And then the hope is that at this point, it doesn't know where it's at. So it doesn't know where it's at, it can't return to where it came from.

SIEGEL: This is safer than blindfolding the croc and spinning him around many times. You're trying to confuse the crocodile's navigational system here.

Mr. HORD: Basically, yes.

SIEGEL: Yeah. How many times have you tried it?

Mr. HORD: We've tried it just twice. Some scientists in Mexico, dealing with the same species, the American crocodile, tested it for a couple of years and had, you know, reported some fairly good success. We saw the article and of course said, hmm, well, we might as well try this. We're already relocating crocodiles. So it can't hurt. Let's see if this works for us.

SIEGEL: And it's still too early to find out whether those two crocs have made it.

Mr. HORD: Oh, way too early.

SIEGEL: Yeah. Why in theory would the magnets block the crocodile's sense of direction or location? Is it - do we assume that their whole system of navigation is magnetic?

Mr. HORD: Well, there's some evidence that they sense the Earth's magnetic field in some way to orient themselves. There's some evidence that they use celestial navigation. They probably use visual cues when they're close to something, or they may even use olfactory stimulus to, you know, to return to their house. It just depends on, you know, probably, you know, the distance that you're talking about.

Certainly, for over long distances, you know, they're going to have to use something that basically is like a GPS, you know, that it says, okay, you were here, you're here now. Here's how you get back to where you were.

SIEGEL: Now, you say, place magnets on the crocodile's head. It sounds a lot easier said than done. It sounds rather dangerous, putting little magnets on the crocodile.

(Soundbite of laughter)

Mr. HORD: It's really not. Of course, we happened to capture these crocodiles anyway, you know, in these situations. So once we capture the crocodile and it is secured, then we're basically just taping these magnets to the crocodile's head. You know, it looks like and seems like it's dangerous, but in reality, you know, if we're doing the things properly, it is not that dangerous.

(Soundbite of laughter)

SIEGEL: Okay. I'll take your word for that. Well, just before I let you go, we should note that the problem for people in Florida, that crocodiles turn up on their property, is evidence, in part, of a solution for the crocodiles, that you've actually been able to bring back the crocodile population in Florida over the years.

Mr. HORD: Yes. The American crocodile population in Florida is really an endangered species success story. However, the result of that recovery is that crocodiles are now being encountered in places where they haven't been seen for several decades, and those areas are places where people live. And, you know, and our job is to try to balance the needs of a recovering species along with public safety.

So, you know, we obviously try to get people to coexist with these crocodiles as much as possible.

SIEGEL: Mr. Hord, thank you very much for talking with us today.

Mr. HORD: My pleasure.

SIEGEL: That's Lindsey Hord, who is a biologist with the Florida Fish and Wildlife Conservation Commission. He joined us from Okeechobee, Florida.

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