New osprey heads are popping over edges of nests all over Chesapeake Country. Puffs of tiny brown Carolina wren fledglings erupt from our porches and shrubs, the second brood since April. Soon, beneath our feeders, cardinal babies, whose sprouts of downy feathers remind us of our own bad-hair days, will beg for food from their parents.
Evidence of nesting is easy to find when the birds hop about our doorsteps. But most of Maryland and D.C.’s 206 species of breeding birds are more secretive.
It took 1,000 volunteers to find them.
For five years, from 2002 to 2006, volunteer birders walked, drove, listened and watched for birds whose behavior indicated they were making nests or feeding young. This data has been compiled in the new second Atlas of the Breeding Birds of Maryland and the District of Columbia.
Sometimes, their searches had unexpected consequences.
One sultry summer night in 2003, Sue Hamilton and Arlene Ripley, the Calvert County coordinator for the atlas project, drove a stretch of rural road in southern Maryland with their windows open, stopping every half-mile to listen.
“We picked up three different owls calling: great horned, barred and screech owls,” says Hamilton, 69, of Port Republic. “We were thrilled. But only five minutes later, the police stopped us and wanted to know what we were doing. The neighbors had called us in as suspicious characters.”
Atlas volunteers had to be ready for anything. Their assigned blocks of 10 square miles each led them not only into parks and woodlands but also into rural and urban neighborhoods. Fortunately, the atlasers found most landowners friendly, allowing entrance to their property and often offering their own observations.
The Job of Atlasing
The volunteers aimed for 90 to 100-plus breeding species per block, except in highly urbanized areas, hoping to equal or improve the numbers documented in the previous 1983 to 1987 atlas. Hamilton’s task was formidable: eight blocks, 80 square miles.
“I drove the roads on a regular basis,” says Hamilton, who then worked full-time at Calvert Marine Museum. “I’d walk for an hour before work or take a drive in the middle of the day. If I had a lot of time, it was a drive and a hike,” she said.
“If I heard the same birds in the same spot over a period of weeks, then I was pretty sure they were residents. If I saw them with food in their mouths, then they were feeding young. I also watched for them carrying nesting material, which I very happily saw in a summer tanager’s mouth down at Solomons.”
Once a species was established as nesting, she could move on to other species. Not wanting to disturb the birds, she and the other volunteers rarely approached a nest.
“If I heard the same birds in the same spot over a period of weeks, then I was pretty sure they were residents,” says Sue Hamilton, who monitored 80 square miles in Calvert County. “If I saw them with food in their mouths, then they were feeding young.”
Politics for the Birds
Even casual bird observers likely have noticed trends over the last 20 years: more Canada geese at a local pond, fewer whip-poor-wills calling from the fields. These trends are echoed in the Second Atlas, which documents Canada geese breeding in 686 more blocks than in the 1980s, for a 187 percent increase. On the other hand, the ground-nesting whip-poor-wills’ numbers indeed have fallen. They were found breeding in 485 fewer blocks, a 45 percent decrease.
But most breeding bird trends go unnoticed except by experienced birders. Dotty Mumford, one of the 61 volunteers in Anne Arundel County, worked on both the earlier and the recent atlas projects. For her, the changes are all too clear.
“I have noticed a decline in woodland birds that migrate here,” says Mumford, 75, who began birding in the 1960s. “Especially the tanagers and thrushes and warblers. I had a hard time finding breeding warblers this time. Every year, more and more species are missing. Every year, fewer birds. When you consider that this is my main occupation, it gets a little sad.
“There are some species that are doing well,” she continues. “Those that like urban habitation, like house wrens and cardinals. But the migrants have a rough life. Their winter habitat is declining, their summer habitat is declining, and their migration route habitat is declining. The weather patterns are changing, and that affects how they migrate also.”
Here in Calvert and Anne Arundel counties, Hamilton and Mumford cite parks and farmland as critical habitat for nesters. Cluster zoning of businesses and housing in Calvert has retained open spaces. For many migrants, unfragmented woodlands are key.
“When woods are cut up, the cowbirds (which lay their eggs in other birds’ nests) and other predators can more easily get to the nests,” Hamilton says. “A lot of migratory birds breed on and near the ground, and they are very vulnerable. When cats wander or are let loose and become feral, they become a real problem. That is a very political issue in Calvert County.”
Another political issue has compromised the habitat of the prairie warbler, a striking yellow bird with red stripes on its back, whose song rises like the notes on a scale.
“Prairie warblers need young pine stands,” Hamilton says. “Along power line rights-of-way, there would be some low pines and there would be prairie warblers. But then they decided to cut all that down.”
In Anne Arundel County, Mumford noted a similar problem.
“When the county herbicided along the power lines, everything was gone,” she says. “Nothing there. No plants for food or shelter. No birds. In a few years, the plants will start coming back. Hopefully the birds will come back, too.”
The loss of young pines, either to natural growth or to removal along rights-of-way or along farmland edges, has led to the decline in prairie warbler numbers in Maryland. They’ve declined 23 percent over the last 20 years. We may all feel that loss. Prairie warblers, like all warblers, eat insects.
Rewarded by the Birds
Atlasing also led to fun discoveries.
“You learn a lot,” Mumford says. “If you see a woodland bird carrying food in its mouth, then you know it is feeding young, since they don’t usually carry food; they eat it. I was having a hard time getting goldfinches with food in their mouths, and I found out that they don’t carry food. They eat food and then regurgitate it into the young. That was something new.”
More than a Coffee Table Read
The Second Atlas of Breeding Birds of Maryland and the District of Columbia, the result of over 61,000 hours of volunteer fieldwork, offers you an armchair look at 206 species of nesting birds. The volume covers atlas procedures and history, plus habitats of Maryland and a review of results.
Two-page species accounts include a color photo, physical and vocal description, probable habitat, behavior and current and historical status in Maryland and D.C. Three maps for each bird depict atlas results: where the breeding species was found during the 2002-’06 atlas, change in species’ distribution since the 1983-’87 atlas, and relative abundance of the species. A table and graph summarize change in breeding bird numbers between the two atlases.
Fascinating and informative, this 540-page volume is recommended for anyone interested in the conservation and diversity of Maryland’s birds. Hardcover, $75.
Second Atlas of Breeding Birds of Maryland and the District of Columbia, edited by Walter G. Ellison. Forward by Chandler Robbins. Johns Hopkins Press. 2010. A project of The Maryland Ornithological Society, the Maryland Department of Natural Resources and the U.S Geological Survey.
Also find Atlas results at the Patuxent Wildlife Research Center’s site: www.pwrc.usgs.gov/bba/