Purple Martins are on the move again. Every year the songbirds migrate across North America and Canada in the spring before returning home to South American at the end of summer.  “People describe it as a National Geographic moment. Everywhere you look there’s a Martin and there are layers of Martins behind those Martins,” said Mary Anne Morris, the Houston Audubon Society education director. Read about the Purple Martin migration at HoustonPublicMedia.org. #purplemartins #birdwatching #birdmigration