Common (and a few red-breasted) Mergansers have for years lingered into late 
April on the Potomac River in Montgomery County. They especially like the 
moderately rocky sections, such as Carderock, above Great Falls, and below 
Violette's Lock. The following were reported to MDOsprey and North American Birds.
 
On May 4, 2003, I saw something very surprising, a female flying out of the 
crown of a tree on the riverbank between Violette's and Pennyfield. Just as you 
see Wood Ducks doing when nesting. I checked back several times, but saw no 
further evidence of nesting. I had never heard of Mergansers "just resting" in 
the trees. They like to sack out on the rocks. I saw several Common Mergs on 
the Potomac that May.
 
On May 30, 2004. I saw a lone chick, still in the downy stage, sliding down 
the rapids below Violettes. I saw it well enough to be sure it was not a Hoody, 
and probably not a Red-breasted.  Since there was no adult around, I wondered 
if a female Common had laid an egg in a Wood Duck nest, which I've read some 
ducks will do to other species. 
 
On May 23, 2006, I saw a hen with six half-grown chicks at Violettes, and saw 
nearly full-sized young there on June 14.
 
On April 25, 2007, I photographed a hen with 14 small chicks at Violettes.
 
And today April 6, 2008, another set of about 14 chicks. I've read that 
Common Mergansers will nest both in tree holes and on the ground. It would be 
interesting to find a nest in MD.
 
Is this too early? On March 25, 2002, I saw a Wood Duck with fleet of chicks 
on the river above Little Falls. Much earlier than you usually see them on the 
river.
 
Dave Czaplak



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