I was with the MOS group at Cylburn this morning (my first time there), and 
we had the same experience as the Chesapeake Audubon folks -- gray and slow. 
I had 32 species, including White-eyed Vireo and Ruby-throated Hummingbird. 
Others in our party had species that I didn't see or hear including Veery 
and flyover Bobolink.

My complete list from eBird is below.

Jim Nelson
Bethesda, MD

Location:     Cylburn Arboretum
Observation date:     9/12/09
Notes:     Walk before Maryland Ornithological Society Board Meeting.  Gray 
and drizzly.
Number of species:     33

Canada Goose     1
Turkey Vulture     2
Cooper's Hawk     1
Ring-billed Gull     2
Mourning Dove     12
Chimney Swift     2
Ruby-throated Hummingbird     2
Red-bellied Woodpecker     1
Downy Woodpecker     4
Northern Flicker     1
Eastern Wood-Pewee     2
White-eyed Vireo     1
Red-eyed Vireo     1
Blue Jay     3
American Crow     2
crow sp.     4
Carolina Chickadee     3
Tufted Titmouse     1
White-breasted Nuthatch     1
Wood Thrush     1
American Robin     26
Gray Catbird     12
Northern Mockingbird     1
European Starling     4
Cedar Waxwing     12
American Redstart     1
Common Yellowthroat     2
Scarlet Tanager     1
Eastern Towhee     3
Chipping Sparrow     12
Northern Cardinal     22
Common Grackle     1
American Goldfinch     1