Ospreys, the only raptors that dive fully into the water for fish, were nearly wiped out in New England by our postwar use of the pesticide DDT. What are they? We were on the top deck, pulling away from Martha s Vineyard, and he was doling out cold hot dogs to his kids while gesturing with his elbow toward a light at the end of the jetty. There, standing guard at the harbor s mouth, were two nearly eagle-sized birds, their stunning black masks and 6-foot wingspans drawing appreciative...