Saturday, May 19, 2007

Rock Creek Park Bioblitz

For the first shift, the fifteen volunteers who registered multiplied into between forty and fifty participants when the shift started. For that shift we checked four locations, and confirmed barred owl at two, screech owl at one, woodcock at one, and nighthawk at one. In the second shift, we found 2-3 additional barred owls and one additional screech owl. In neither shift were we successful in rousing a great horned owl, despite efforts at several stops.

The basic method for finding owls involves playing recordings of the species being sought and waiting for a response. For great horned owls, the recordings include a distressed rabbit, which has a disturbing sound. Barred owls make the most varied set of responses, which include screams, barks, cackling laughter, and other weird noises. The barred owl at the last stop started its response with a wail. (Under most circumstances, searching for owls by night in Rock Creek Park requires special permission from the Park Service, which is only available to people or groups conducting legitimate research.)

After napping for a couple hours at the Nature Center, I woke up to the sound of birds singing. Red-eyed vireos, wood thrushes, robins, and some blackpoll warblers were all in full song when I headed out for some early morning birding. As I walked down to the Maintenance Yard, I saw a veery and heard many Swainson's thrushes, which seemed to be almost as common as robins last night and this morning.

According to radar maps there was barely any migration along the east coast last night. The overcast skies in the early night must have discouraged migrants. Despite the lack of movement overnight, it was one of the best warbler mornings I have ever had. The only comparable morning that comes to mind is a walk along Cockpit Point Road in Virginia last spring. I saw and heard about eighteen species of warblers in and around the Maintenance Yard in the course of about three hours.

When I first arrived at the Yard, I was alone with the birds. I quickly saw a scarlet tanager near the entrance, heard a Baltimore oriole, and then saw yellow, chestnut-sided, hooded, ovenbird, and redstart near the ravine. A female Cape May warbler foraged for a few minutes in one of the locust trees. As other birders slowly trickled into the Yard, more warblers appeared - magnolia, Canada, blackburnian, black-throated blue, black-throated green, bay-breasted, and northern parula. About an hour after I saw the female Cape May, a male appeared in the same tree and gave great looks to all of the assembled birders. A Louisiana waterthrush sang a few times from the bottom of the ravine, and a prairie warbler perched and sang in the meadow behind us. Of all those birds, the chestnut-sided, magnolia, and black-throated blue warblers seemed to be present in the greatest numbers, and the female blackburnian kept reappearing at the edge of the vines.

Once the warbler action slowed, I made my way back to the Nature Center so that I could catch the bus to go home. The last bird was a gray-cheeked thrush on the trail leading back to the horse center. It stood out from the numerous Swainson's thrushes because of its gray face with no eye-ring. It was a great way to close out the morning.


Red-shouldered Hawk
American Woodcock
Mourning Dove
Yellow-billed Cuckoo
Eastern Screech-Owl
Barred Owl
Common Nighthawk
Chimney Swift
Ruby-throated Hummingbird
Red-bellied Woodpecker
Downy Woodpecker
Eastern Wood-Pewee
Acadian Flycatcher
Eastern Phoebe
Great Crested Flycatcher
House Wren
Gray Catbird
Eastern Bluebird
Gray-cheeked Thrush
Swainson's Thrush
Wood Thrush
American Robin
Blue-gray Gnatcatcher
Carolina Chickadee
Tufted Titmouse
White-breasted Nuthatch
European Starling
White-eyed Vireo
Red-eyed Vireo
Northern Parula
Yellow Warbler
Chestnut-sided Warbler
Magnolia Warbler
Cape May Warbler
Black-throated Blue Warbler
Yellow-rumped Warbler
Black-throated Green Warbler
Blackburnian Warbler
Prairie Warbler
Bay-breasted Warbler
Blackpoll Warbler
Black-and-white Warbler
American Redstart
Louisiana Waterthrush
Common Yellowthroat
Hooded Warbler
Canada Warbler
Scarlet Tanager
Eastern Towhee
Chipping Sparrow
Northern Cardinal
Indigo Bunting
Common Grackle
Baltimore Oriole
American Goldfinch
House Sparrow