Birds Of Manassas

In 1999, the National Capital Region of the National Park Service (NPS) initiated an inventory and monitoring program to identify at least 90% of all expected species of vertebrates and vascular plants in its parks.

Early in 2001, Biological Inventories Coordinator Marcus Koenen recruited experienced volunteer birders to conduct avian surveys at Manassas National Battlefield Park (MNBP), one of the first of six parks to be inventoried. The survey's goal was to provide a permanent record of the bird species found in the park, as well as to establish baseline data for monitoring future changes in bird populations. Other goals were to document the abundance and distribution of "species of concern," to provide information that might be used to manage the parks' natural resources, and to help local and state governments in land use planning. Participants in the survey were Larry Cartwright, Laura Catterton, Bart Frazier, Kurt Gaskill, Sue Heath, Paul Kane, Bob Klarquist, Linda Millington, Rich Rieger, Dan Smith, Paula Sullivan, Dorothy Tella, Porter Ward, and Christopher Wilson. In the fall of that year John Sinclair took over as Biological Inventories Coordinator.

Over the course of the next 18 months, teams of birders armed with binoculars, notepads and pencils took to the fields and forests of MNBP, which is comprised of about 5,000 acres. They followed established woodland paths and deer trails, crossed streams and scanned ponds to observe birds flying overhead, perching in trees, and skulking in scrub in an effort to document avian life in the park. They kept careful notes of all birds seen and/or heard and observed them for signs of nesting behavior.

Survey teams were in the field at least twice a month and typically spent about 3 to 4 hours on each visit. In between scheduled surveys, some team members visited the park on their own and provided additional data. By the time the project was concluded officially in October of 2002, the NPS reported that the goal of documenting 90% of the avian species had been reached.

SURVEY METHODOLOGY: The Park was divided into six sectors (See link to Map) and birders recorded their observations by sector on datasheets provided by the NPS. They kept a running total of individuals of each species seen or heard and noted the breeding or status code of each. Following guidelines provided by the NPS, the codes assigned to the various species of birds were as follows:

• OB -- Observed. Used when habitat is inappropriate for breeding or when data is insufficient to confirm any other status.
• WR -- Winter Resident. Observed for more than two months during the winter period.
• MG -- Migrant. Observed only during the species' spring and/or fall migration for not more than two months. Not a breeder or winter resident.
• PO - Possible Breeder. Observed in suitable nesting habitat, e.g. singing male. Exhibiting no other breeding behavior.
• PR -- Probable Breeder. Observed exhibiting one or more of the following 7 behaviors suggestive of nesting:
  • PR-M = Seven or more singing males
  • PR-S = Singing male on territory
  • PR-P = Pair (male and female)
  • PR-T = Territory defense
  • PR-C = Courtship, copulation
  • PR-V = Visiting potential nest site
  • PR-A = Agitated behavior
  • PR-B = Nest building by wrens and woodpeckers
• CO -- Confirmed. Observed exhibiting one or more of the following 11 behaviors which confirm nesting:
  • CO-CN = Bird with nesting material
  • CO-PE = Physiological evidence
  • CO-NB = Nest building (other than wrens and woodpeckers)
  • CO-UN = Used nest
  • CO-DD = Distraction display
  • CO-ON = Occupied nest
  • CO-FC = Food carry
  • CO-FS = Fecal sac
  • CO-NE = Nest with eggs
  • CO-NY = Nest with young
  • CO-FL = Fledgling

DATABASE PROJECT: In the fall of 2002, a secondary project was begun by some of the survey volunteers to determine and begin tracking the early and late dates of migrant species, to assess the abundance of species by sector, and to uncover obvious gaps in the existing survey data. Data from the NPS-sponsored Bird Inventory and from other recent sources were entered into a database called the Manassas Battlefield Birding Database Project.

SURVEY RESULTS: The database includes data from 209 individual surveys collected by volunteers during a National Park Service-sponsored Bird Inventory during 2001-02 and the 2002 Christmas Bird Count, as well as data from occasional surveys at the battlefield from October through December 2002.

Records compiled: 6,863
Total bird observations: 69,271
Total number of species: 155
Year--round residents: 41
Winter residents: 13
Migrants: 35
Confirmed breeders: 50
Probable breeders: 14
Possible breeders: 18
Observed only: 25
Species of concern: 16 (6 are confirmed breeders)

(To see the lists of birds in each of these breeding or status categories, see link to Bird Survey Lists by Category.)

Paula Sullivan
Group Leader