This investigation was designed to detect effects of electromagnetic (EM) fields produced by an extremely low frequency (ELF) antenna system on bird species breeding in or migrating through northern Michigan. Our null hypothesis was that no differences in bird species richness and abundance existed between areas that were close to the antenna and areas that were far enough away to be unaffected by the antenna. We conducted spring migration, breeding, and autumn migration bird counts on 40 reference and 40 treatment 500-m transects for 8 yr (3 yr before and 5 yr after the antenna became fully operational). Characteristics examined included total species richness and abundance and abundances of common bird species. We analyzed changes in species abundances over time on treatment and reference transect segments using a repeated measures ANOVA. For this test, a significant interaction indicated that changes in bird abundance over time were not equal in treatment and reference areas. Approximately 10% of tests (11 of 111) at the community or species level had a significant (P < 0.05) interaction. However, no significant interactions found at the community or species levels were consistent among seasons. Moreover, patterns of change in abundance over time in reference and treatment areas for parameters that had a significant interaction were not attributable to EM field exposure.
- Birds, breeding
- Birds, migration
- Electromagnetic fields, response to