I enjoyed this very brief article regarding early morning weather
radar showing odd results.  The article speculates that it might be
martins rising to feed from a large communal roost.

http://weblogs.marylandweather.com/2009/08/bay_birds_caught_on_radar.html

Any birders knowledgeable about this area (mouth of the Bush River)
care to speculate or add to the conversation?

Good Birding,

Dan Haas
West Annapolis, MD