RESPONSE OF BREEDING AND MIGRATING BIRDS TO EXTREMELY-LOW-FREQUENCY ELECTROMAGNETIC-FIELDS

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. O ur null hypothesis was that no differences in bird species richness an d abundance existed between areas that were close to the antenna and a reas that were far enough away to be unaffected by the antenna. We con ducted spring migration, breeding, and autumn migration bird counts on 40 reference and 40 treatment 500-m transects for 8 yr (3 yr before a nd 5 yr after the antenna became fully operational). Characteristics e xamined included total species richness and abundance and abundances o f common bird species. We analyzed changes in species abundances over time on treatment and reference transect segments using a repeated mea sures ANOVA. For this test, a significant interaction indicated that c hanges in bird abundance over time were nor equal in treatment and ref erence 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 wer e consistent among seasons. Moreover, patterns of change in abundance over time in reference and treatment areas for parameters that had a s ignificant interaction were not attributable to EM field exposure.