One MDOSPREYer responded to me offlist saying these were 
show pigeons, specifically "Splashed Fan Tailed Pigeons".

D

-- 
Derek C. Richardson, College Park, PG County, MD
http://www.astro.umd.edu/~dcr/Archives/Photos/birds.html

On Wed, 6 Sep 2006, Bruce and Karen Stewart wrote:
> Last weekend Derek Richardson posted a query and pictures of two pigeon
> sized, white birds at Riley's Lock.  The male had a ruffed grouse- like
> tail.  I saw them also and was also hoping somebody knew what they were.
> Any guesses?