The 1999-2003 Summary of the North American Breeding Bird Survey

Data from the North American Breeding Bird Survey were used to estimate continental and regional changes in bird populations for the 5-yr period 1999-2003 and the 2-yr period 2002-2003. These short-term changes were placed in the context of population trends estimated over the 1966-2003 interval. During 1999-2003, 41% of all species exhibited positive trends over the entire survey area, while 64% of all species exhibited positive change between 2002-2003. The continental and regional percentages of species with positive trends were also analyzed for 12 species groups having shared life-history traits. Survey-wide for the entire survey period, grassland birds exhibited the lowest percentage of increasing species (14%), with their sharpest declines occurring in the West during 1999-2003 (10% increasing). During 1999-2003, short-distance migrants experienced significant declines in all regions, where numbers of species with increasing trends ranged from 22% - 34%. Most species fared well during the 2002-2003 period, with 64% (P < 0.05) increasing survey-wide. This was primarily a result of increases in the Central and Western BBS regions where 21 of 24 species groups exhibited significant increases in the number of species with positive trends.