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

To test the hypothesis that absence of song-perches limits use of habi tat by breeding grassland birds, we placed artificial l-m tall song-pe rches in two experimental plots in Maine. We. found no evidence to sup port this hypothesis. Although these artificial song-perches were used frequently as singing perches, species composition and territory dens ities on these plots were nearly identical to those found on two refer ence plots. Furthermore, we found no differences in territory densitie s between species that sing flight-songs and species that sing from fi xed perches. Our results indicate that: (1) the absence of song-perche s did not limit grassland birds at this site, and (2) that a variety o f habitat parameters probably influence the habitat selection process. Thus, it appears unlikely that the long-term population declines repo rted 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, p ossibly on both the breeding and wintering grounds, are involved in th ese long-term declines.