The Breeding Bird Survey has been monitoring bird population changes in the U.S.A. and Canada since 1966. Each cooperator makes 50 3-minute stops at 0.8-km intervals along randomly selected roadside routes in 4 to 4 1/2 hours on one morning in June of each year. Data from the 1500 to 1600 routes are entered on magnetic tape, edited for accuracy, and then used for statistical analysis of population change at four geographic levels: physiographic region; state or province; region (eastern, central and western); and the continent. Examples of use of the data are: (1) detection of year-to-year changes in continental or rcgional populations; (2) use of population indices to show long-term population changes; (3) range expansion and contraction at the state level, including some of the reasons for those changes and documenting the associated population shifts within the original range; (4) mapping distribution and relative abundance on either a state, regional or continental scale; (5) mapping changes in abundance; and(6) comparing breeding with winter distribution. Future potential uses will include estimates of total continental populations and indices of environmental quality.
