Thousands of purple martins flock to Nashville

So many purple martins are gathering in Nashville that it’s visible on national weather radar.
Thousands of the blue and purplish birds have chosen an urban spot near Interstate 24 to gather before leaving to winter in Brazil. The sight is drawing a growing number of bird watchers.
The Tennessean reports the birds began showing up in the area last week.
Tennessee Wildlife Resources Agency ornithologist Scott Sommershoe has estimated the number at 48,000.