Sometime in the first 10 days of May, weather conditions prompt the big migrations of tropical birds north. But for some, the migratory season starts much sooner, in February and more in March.

The ancient instinct to migrate always has fascinated renowned birding expert Kenn Kaufman. But even he has been taken by the particular experience of the migration in Ohio, along a stretch of Lake Erie where the marshes represent the last gasp of the once sprawling Great Black Swamp.

Kaufman talks about his new book on the topic, "A Season on the Wind: Inside the World of Spring Migration."

Guests:
Kenn Kaufman, author of Season on the Wind: Inside the World of Spring Migration