英语听力：自然百科 海牛

The Florida Everglades, each winter, hordes(群) of manatees congregate in the warm waters here to survive the cooler weather. But they are not alone. Manatees share these waterways with boaters, and that has put them in a harm's way(危险的境地).

“Manatees are considered legally endangered, both on the federal list and also on the state list. The main cause of mortality -- for manatees are being hit by watercraft.”

For nearly four decades, National Geographic grantee Buddy Powell has worked to study and protect manatees around the world. Now he wants to know how many manatees remain, to see if wild populations are recovering or not.

“That’s why this particular study, you know, funded by National Geographic, is so important, because it’s gonna help give us those numbers and those insights into what’s going on in this very remote area, the Everglades.”

To find the manatees, Buddy, who is also a pilot, takes to the skies.

“We use airplanes quite a bit because you can see manatees pretty well in the water, and so we use aircraft to count them and also look at their distribution and find out where their habitat is.”

With Buddy covering the air, his colleague Lucy Keith heads out on the water.

“Oh, I just saw a nose pop up. Excellent, there are a few over here.”

Armed with the camera, Lucy photographs each animal she sees.

While most people try to keep blemishes(缺点，瑕疵) out of their photos, this researcher tries to document as many as she can.

“Many manatees, even though the Everglades is thought of as a remote place, many manatees here still have boat scars or other marks on them. And those scar patterns on manatees can be as unique as a fingerprint.”

Lucy carefully logs each animal’s scars and markings so they can be compared with a statewide database.

It’s sort of like a giant game of concentration. We try to match the manatee picture to other photographs already in the database.”

So far the results of the study are encouraging.

“What we are finding primarily for the Everglades is that most of the manatees have not been in that database before.”

This could mean that there are more manatees in Florida than experts previously thought. And the study has also shown that manatees will occasionally fake their own death, so to speak.

Animals that had been seen some place else and thought to either have died or disappeared. We’ve located some of those here. So we think that there is a very good chance that some of these animals that, and we may have considered, were dead before, are just over wintering, down here in the Everglades.

The team will continue to canvass(详细考察) the Everglades in search of manatees. And with each new sighting, they are better prepared to protect these magnificent marine mammals and thewatery labyrinth they called “home”.