Yesterday I attended a bird walk in the National Arboretum for International Migratory Bird Day. The walk was led by David Sibley. Ellen Paul sent out this list of all the birds recorded.  I personally didn't see them all but for the purposes of Maryland-DC record-keeping I've annotated the list with numbers where it might be useful (Bob, you'll be proud of me!).
 
Mallard
Red-shouldered Hawk
Mourning Dove
Yellow-billed Cuckoo
Chimney Swift
Ruby-throated Hummingbird
Red-bellied Woodpecker
Hairy Woodpecker
Pileated Woodpecker
Eastern Phoebe  1 singing 
Great Crested Flycatcher
Red-eyed Vireo - several singing 
Yellow-throated Vireo  - 2 singing 
Blue Jay
American Crow
Fish Crow
Carolina Chickadee
Carolina Wren
Ruby-crowned Kinglet
Blue-gray Gnatcatcher - several 
Eastern Bluebird
Veery  - 3+ 
Wood Thrush  - several singing 
American Robin
Gray Catbird
Brown Thrasher
European Starling
Blue-winged Warbler - 1or 2  singing 
Northern Parula - 3 singing, 1 female nestbuilding 
Yellow Warbler
Cerulean Warbler - 1 male
Yellow-rumped Warbler -  many singing 
Black-throated Green Warbler
Palm Warbler  1 seen (eastern race) 
Worm-eating Warbler  1 heard singing 
Ovenbird  - several singing 
Common Yellowthroat  - 1 singing 
Hooded Warbler  1 singing (great views) 
Scarlet Tanager  - 2 singing 
Eastern Towhee
Chipping Sparrow
Field Sparrow
Song Sparrow
White-throated Sparrow  - many singing 
Rose-breasted Grosbeak  - 1 male 
Northern Cardinal
Blue Grosbeak  - 1 singing 
Indigo Bunting  - 1 singing 
Red-winged Blackbird
Common Grackle
Brown-headed Cowbird
Baltimore Oriole  - 1 heard 
House Finch
American Goldfinch
House Sparrow 
[CURSON, David] 
David Curson, PhD 
Director of Bird Conservation, 
Audubon MD-DC, 
2437 Eastern Avenue, 
Baltimore  MD  21224 
Tel: (410) 558 2473 
E-mail: