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The 2003-2008 summary of the North American Breeding Bird Survey

December 22, 2011

Data from the North American Breeding Bird Survey were used to estimate continental and regional changes in bird populations for the 6-yr period 2003-2008 and the 2-yr period 2007-2008. These short-term changes were placed in the context of population trends estimated over the 1966-2008 interval. Across the entire survey area, a higher proportion of species exhibited positive growth during 2003-2008 (64%) than during the long-term (46%) or the more recent 2-yr-term (39%). The 2003-2008 growth occurred relatively evenly across the Western, Central, and Eastern BBS regions, with 59%, 66%, and 61% of all species increasing, respectively. We additionally evaluated the proportion of species with positive trend estimates in each of 12 life-history based groupings at continental and regional levels. Survey-wide, birds in the grassland guild demonstrated the lowest proportion of positive trends over the entire survey period (21% increasing), with significant declines occurring in both the Eastern and Western regions (5% increasing and 18% increasing, respectively). Birds in the wetland breeding guild exhibited the greatest proportion of positive trends, with a significant number of increasing species (between 77-90%) occurring in all three BBS regions during 2003-2008.