Human impacts on regional avian diversity and abundance

Collaborators: Curtis H. Flather, Anna M. Pidgeon, Volker C. Radeloff, and Roger B. Hammer

Bird population levels can vary greatly across both the extent of their range and among years. Although numerous mechanisms have been put forth to explain this variation, human effects may be particularly important. To assess the role of human influence on bird populations, we investigated both anthropogenic land cover and housing density, in relation to total, native, and exotic species richness and trends of 137 species across 408 replicate landscapes in the Midwest U.S. We used housing density and anthropogenic landuse as indices of human influence across the Midwest United States to test three hypotheses (productivity, intermediate disturbance, ecosystem stress) relating human influence to species diversity and abundance. Total and native avian richness was highest where human influence is lowest, whereas exotic species showed the opposite response. Abundances of 53% (73 of 137) of the species studied responded to human influence, with 50.7% species clearly decreasing, and only 17.8% clearly increasing. Our findings were consistent with the ecosystem stress hypothesis and suggest using pre-emptive conservation action, whereby areas with little human influence are given conservation priority.

Acknowledgements:
Financial support for this research was provided by the Michigan Agricultural Experiment Station, N.S.F. Interdisciplinary Informatics Fellowship, U.S.D.A. Forest Service, North Central Research Station and Rocky Mountain Research Station, and U.S. E.P.A. STAR Fellowship program.

Presentations:
Lepczyk, C., V. Radeloff, C. Flather, A. Pidgeon, R. Hammer, and J. Liu. 2004. The influence of human-dominated landscapes on breeding birds in the Midwest United States. 89th Annual Meeting of the Ecological Society of America, Portland, OR.

Lepczyk, C.A., V.C. Radeloff, C.H. Flather, and J. Liu. 2003. The human influence on birds across Midwest landscapes. 4th European Ornithologists’ Union Conference, Chemnitz, Germany.

Lepczyk, C.A., V.C. Radeloff, C.H. Flather, and J. Liu. 2003. The human influence on birds across Midwest landscapes. 17th Annual Meeting Society for Conservation Biology, Duluth, MN.