BM: Sure. Well, of course, the big thing here was that out-that the birds were not migratory and that we'd still have a problem within this population. I started some prey studies back in the early 90's and also a collection of peregrine feathers for analysis of contaminates. Of course, DDT and DDE were outlawed many years ago. Many years ago, but it-it's still made and shipped to foreign countries. And, of course, we do border with old Mexico and there's a lot of farmland upriver from the Big Bend country, and so that was a concern. But my main concern, I-I-I kept coming back to the river. I kept, you know, it's-there's-our production there would always tend to be lower than anyplace else. And so I-I did a lot of work trying to figure out what could be the problem in the food chain that's causing this reproductive problem in the peregrines. Nest failures are so very common. We have increased the number of peregrines here. And one of the reasons because-is because we increased our survey area. When the studies first started out, they were only looking at the three major canyons within Big Bend 0:23:52 - 2157National Park, Santa Elena, Mariscal, and Boquillas. Now we look at about a three hundred mile area of river. And my surveys extend into the Maderas del Carmens, in Coahuila, Mexico, Sierra del Carmen, and into the Salaniqa del borro. Also we-we went back and looked at any old sites that had ever had any records of peregrines. And all-everything kept pointing back to the problem-the main problem in reproduction was along the river. So I did a series of different samples and mercury has cropped up in all of our samples. Well it-this area is a-I mean, the rivers-it-there's a natural source of mercury in the whole lower Big Bend because of all the old cinnabar mercury mines that were in that area. And when you pull out the topo maps and you look at it, all 0:24:40 - 2157of these drainages from this country, particularly the Terlingua area, drain into the Rio Grande. Mercury is a very-very harmful chemical. Once it is in the food chain, it changes to methyl mercury. It builds up just like DDT and DDE to a certain extent. And I was seeing a lot of-of really abnormal behavior in some peregrines. It was-it's-it's very frustrating to watch pairs go through a courtship period and lay eggs and then lose that clutch of eggs. They never hatched and the-the birds would sometimes try to re-nest. Most of those attempts were failures. And-and we still have problems today and we're still doing work. We are in a, I think, a very unique situation because the falcons here in the lower Big Bend area are non-migratory. They're also to a large extent, geographically isolated. They-we don't receive any-our recruitment rate is very, very slow. If we lose one of an adult pair to old age, or, you know, whatever-whatever reason, it may take us three years to recruit a mate. Where in other populations, in less 0:25:53 - 2157than twenty-four hours a mate's been recruited. So we have some recruitment problems. There's just a number of factors. And it's-it's a puzzle that we keep working on and-and a number of people, of course, have helped me, you know, through the years on this, Peregrine Fund, different individuals that have worked with raptors over the years and-and we've all put our head together to try to come up with a solution to this. And-and if mercury is a problem, how can we go about solving it? We don't have enough samples yet to really say anything definitive as to whether mercury is the main problem or not. But we are looking at mercury very hard.DT: What sort of effect would mercury have on an animal?0:26:34 - 2157