JUDY WOODRUFF: After combing 18,000 square miles of forests and isolated swamps, researchers have found some 125,000 western lowland gorillas in the northern part of the Republic of Congo.
Until now, scientists believed there were only about 50,000 of these endangered gorillas left, their numbers devastated by hunting and disease.
But the new survey by the Wildlife Conservation Society reveal that more than double that number are swinging, eating, and thriving in this one remote, swampy region of central Africa.
And here to tell us more about this remarkable finding is Steven Sanderson. He’s the president and CEO of the Wildlife Conservation Society.
Steven Sanderson, first of all, introduce us to the western lowland gorilla. Who are they? What do they look like?
Developing a conservation strategy
STEVEN SANDERSON, the Wildlife Conservation Society: Well, they're a recognizable gorilla. They're a large primate. They are one of four subspecies of gorilla that live throughout the western part of the Congo basin.
They're gentle giants, as they're called. They eat mainly leaves and shoots and fruit, and live in families, have a long life, are slow to reproduce, maybe one infant every five years per female who's reproductive.
JUDY WOODRUFF: And why were they considered -- why were they listed as endangered?
STEVEN SANDERSON: They've been listed as critically endangered since last year.
The community of science that concerns itself with the health of endangered species met and found that a rough estimate of maybe 20 years ago of 100,000 animals throughout the seven countries of the Congo basin may have been reduced by half from poaching, and commercial wildlife trade, and diseases such as Ebola. So there has been great concern in the community.
This number allows us to understand better what the total population might be, and allows us to think through a strategy for their conservation, and also to review that degree of vulnerability.
The gorilla-finding methodology
JUDY WOODRUFF: So how big a deal, how important is this discovery?
STEVEN SANDERSON: It's a huge deal. For one thing, the original estimates in the 1980s of about 100,000 animals that may have been decimated to half that number by now, that was a rough number, and there were many pockets of the Congo that were just too inaccessible to do scientific surveys.
So our undertaking this survey, over the years 2006 and 2007, added measurably to the scientific knowledge, but it was really stunning to find this great abundance of animals and the opportunity to protect them.
JUDY WOODRUFF: How did the -- Dr. Sanderson, how did the researchers find them? And how in the world did they count them?
STEVEN SANDERSON: Well, you have to be out there. So our stock in trade is that we commit ourselves to conservation in place over decades of time, and we've been there for 20 years or so, working with the government and working in these very difficult places.
During that time, we saw signs -- our researchers, our conservation scientists saw signs that there were more gorillas than met the eye, as it were, but they're very reclusive.
And we followed them, and looked for tracks and droppings, and so forth, but the main methodology revolves around nests that they leave. And so there was a great nest-counting survey. And then there are statistical techniques that are applied to that to give us estimates of density and abundance.
Confidence in the numbers
JUDY WOODRUFF: How is it, do you think, that the earlier estimate was so off? I mean, how were these animals able to thrive as they have?
STEVEN SANDERSON: Well, it's extremely difficult country. It's very swampy. It's a very dense, closed forest. There are openings, but there are forbidding bodies of water and very difficult conditions, almost no infrastructure. You can't fly over forest animals and count them in the way that you can savannah animals.
So partly it was the remoteness. And, secondly, it's the reclusiveness of the animal itself. It doesn't like to be out in the open and in view of humans or other possible dangers. And so it's extremely difficult to count them.
The early estimates I don't think benefited from a longstanding presence or a sample size that we were able to measure this time around.
JUDY WOODRUFF: So do you feel confident about this new number...
STEVEN SANDERSON: We feel very...
JUDY WOODRUFF: ... 125,000-plus?
STEVEN SANDERSON: We feel very good about the number, because our folks were so skeptical about it, they ran it several times, and they worried about it, and they had others review it.
This is like any other scientific finding. It will be put out into the community, and reviewed, and amplified, and criticized, and enriched by the dialogue in the community and among conservationists that will go forward from here. But we feel very strongly that this is a good number; it's certainly the best number out there.
Ongoing dangers in Congo
JUDY WOODRUFF: So are these gorillas still endangered?
STEVEN SANDERSON: Yes, there's no question that the number does not betray the danger. So we don't know, for example, the degree to which these populations have been affected by human diseases.
And gorillas are susceptible to human diseases. Almost all of the diseases that we suffer, they suffer, as well, only with not the same immunity.
They also suffer from these hemorrhagic fevers such as Ebola, and one outbreak can kill 1,000 animals, so it's a great danger.
The other great danger -- and it's accelerating -- is that the expansion -- the Asian expansion has increased the value of commodities in the Congo basin and interest in other nations in exploiting those commodities for human use.
So I think we'll see greater pressures than have been in the past to take forest products out, and minerals, and other resources that are in this area.
The Congo Republic deserves great credit for having made some good decisions for protection and sticking by those decisions. And it's incumbent upon us to make that a compelling mission for the future.
JUDY WOODRUFF: Well, Steven Sanderson of the Wildlife Conservation Society, thank you so much.
STEVEN SANDERSON: Thank you, Judy. It's good to be with you.