DO ARTIFICIAL SONG-PERCHES AFFECT HABITAT USE BY GRASSLAND BIRDS IN MAINE

To test the hypothesis that absence of song-perches limits use of habitat by breeding grassland birds, we placed artificial l-m tall song-perches in two experimental plots in Maine. We. found no evidence to support this hypothesis. Although these artificial song-perches were used frequently as singing perches, species composition and territory densities on these plots were nearly identical to those found on two reference plots. Furthermore, we found no differences in territory densities between species that sing flight-songs and species that sing from fixed perches. Our results indicate that: (1) the absence of song-perches did not limit grassland birds at this site, and (2) that a variety of habitat parameters probably influence the habitat selection process. Thus, it appears unlikely that the long-term population declines reported for many species of grassland birds in eastern North America can be mitigated by simple measures such as adding artificial song-perches to grassland habitats. It is more likely that a variety of factors, possibly on both the breeding and wintering grounds, are involved in these long-term declines.