Blocks and Regions


The basic survey unit on which data were collected was the “block,” defined as one-sixth of a standard U.S. Geological Survey 7.5-minute topographic map, the same unit used in the First Breeding Bird Atlas. Blocks are approximately 24.8 square kilometers (9.6 square miles) in area and were categorized as Border, Priority, or normal based on their position. Border blocks fell along the state’s eastern, southern, and western borders, where the block boundary extended into a neighboring state.  Priority blocks were defined as all blocks in the southeastern corner of the topographic quadrangle, or block 6, wholly within the state.  Priority blocks were targeted for additional coverage. In Border blocks, volunteers were instructed to report birds only seen or heard within Pennsylvania.  The remaining blocks were considered “normal” blocks. The second Atlas included 4,937 blocks, of which 787 were priority blocks and 202 were border blocks.

Atlas Regions

The DeLorme Pennsylvania Atlas and Gazetteer® (DeLorme 2003) was used to delineate atlas regions and a local “Regional Coordinator” was assigned to oversee survey effort within that area.  Each full DeLorme Atlas map page (Region) contained the equivalent of 14 USGS quadrangles, or 84 atlas blocks. For regions where most of a page fell outside of Pennsylvania, two or three pages were joined together to form one region. Fifty-seven regions were defined, of which 46 were a full page of the DeLorme Atlas (84 blocks), while the remaining 11 regions consisted of more than one page.

A list of Regional Coordinators is provided under the Credits tab.