Recent declines in bird populations brought me to Dr. BRUCE STEIN: who has spent much of his career on the topic of wildlife biodiversity. Recent declines in bird populations brought me to Dr. Bruce Stein, who has spent much of his career on the topic of wildlife biodiversity. First of all, the decline of almost a third of the birds is in the United States, not the world in North America, continental U.S. and Canada. What is the cause of the decline? There was a study that was published in the journal Science that showed almost a 3 billion bird decline since the 1970s in North America. That's about a 29 percent decline. And we're talking about number of individual birds that are flying around or as the case may be, not flying around. And a lot of these are actually common species, not the rare ones that we often think about, things like redwing blackbirds and meadow larks. And so you do have to ask what's going on here, because this is a real wakeup call. It's clear that there's a number of things that are contributing to these declines. One of the major is loss of habitat, conversion of habitat from natural ecosystems to agricultural production or loss of forest. So that's one thing. The encroachment of invasive species is another thing and the use of pesticides being a third. There's a variety of factors and there are often species specific. We also know that when we identify certain things that are threatening a particular group of species, we have the ability to turn it around in another star and not surprisingly, the impact of bird loss on agriculture.