The role of human activities in shaping ecological patterns at continental and global spatial scales has been understudied. This is due in part to the assumption that these large-scale patterns are generated primarily through non-human processes.

A study in a forthcoming issue of the Journal of Biogeography, using data on breeding bird assemblages in North America from 1968 to 2003, finds evidence suggesting that human activities have played a role in shaping large-scale ecological patterns. Dr. Frank La Sorte from New Mexico State University used several novel analytical approaches to examine bird assemblages and their geographic ranges in North America to test for patterns of change over time.

His findings suggest that a majority of bird species within these assemblages experienced geographic range expansion and a majority of bird assemblages experienced an increased abundance of common species over the 36 year time period.

Overall, the results indicate that common species have become more prevalent across bird assemblages in North America within recent human history and human activities, therefore, cannot be ignored as a possible causal factor when assessing these patterns.

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New Mexico State University