Atlas of the Breeding Birds of Maryland and the District of Columbia
This was the result of a 5-year cooperative study with the Maryland Ornithological Society and the Maryland Department of Natural Resources. Each of Maryland's 1,256 5-km (25 sq km) blocks was surveyed for breeding birds using the standard categories of Possible, Probable, and Confirmed breeding. Special features include: (1) coverage of all blocks instead of a random sample; (2) one-third of the state (including the most rapidly changing counties) was covered in quarterblocks (2.5 km on each side) to facilitate detecting future changes; (3) quantitative sampling (miniroutes) was completed in more than half the blocks; (4) a 2 percent statewide random sample of blocks was searched for about 30 hours each by Patuxent professionals to evaluate efficiency of coverage by the volunteers; (5) besides species maps for 1983-87, the atlas also includes distribution maps from the 1950s; (6) life history data are based largely on unpublished Maryland information.