Mass Audubon’s Breeding Bird Atlas
The Breeding Bird Atlas (BBA) (LINK) is a collection of data about all of the birds that breed in a particular state or region. Mass Audubon’s first BBA was carried out from 1974-1979. BBA2 (set to be finished in late 2012/early 2013) will cover 2007-2011.

Long-Term Breeding Bird Surveys
The Patuxent Wildlife Research Center(PWRC) of the United States Geological Survey coordinates two national surveys of breeding bird to track long term trends.

Additional Data Sets
PWRC maintains a repository of avian point count data for studies throughout the United States.

The Avian Knowledge Network (AKN) is an international organization of government and non-government institutions that brings together observational data on birds with the goal of understanding the patterns and dynamics of bird populations across the Western Hemisphere. eBird, which many birders use to organize and report their observations, is one of the data sources within AKN.

Breeding Bird Sampling Methodology
Handbook of Field Methods for Monitoring Landbirds by Ralph, C.J., G.R. Geupel. P. Pyle, T.E. Martin, and D. F. DeSante. 1993. US Dept. of Agr., USFS, Pacific Southwest Research Station. General Tech Report PSW-GTR-144. 41 pp.

Managing and monitoring birds using point counts: standards and applications by Ralph, C.J., S. Droege, and J.R. Sauer. 1995. Pp. 161-168 in C.J. Ralph, J.R. Sauer, and S. Droege, eds. Monitoring Bird Populations by Point Counts. USDA Forest Service Pacific Southwest Research Station. General Technical Report PSW-GTR-149.