The Washington Post recently ran an article highlighting research by Prof Chris Tonra from The Ohio State University. Chris, who has spoken at Columbus Audubon programs in the past, headed research that located the wintering range for the species. The numbers of Prothonotary Warblers showing up in the US and Canada have declined significantly in recent years, and knowing where the bird winter is critical for conservation.
You can see the article on the Washington Post Web site.