Apr 26, 2002 — Many North American birds are in serious decline. But scientists aren't sure what's wrong because birds are hard to count. The problem is partly that birds often migrate long distances between wintering sites and summer breeding grounds. Usually they fly unobserved at night. And in many cases scientists don't know what route they take. However, a new technique promises to solve this problem. The Great Lakes Radio Consortium's Daniel Grossman has our story.