The Condor 90:339-348

For the first time, the effect of mechanical clearing of a native ohia/koa (Metrosideros polymorpha)/(Acacia koa) forest has been determined on some Hawaiian birds. Counts conducted on Keauhou Ranch, Island of Hawaii, at 6-month intervals, from December 1977/January 1978 through June/July 1983, showed that species richness and bird abundance were lower in the mechanically cleared or treated plots than on an adjacent control plot. In the treated plots, the nonnative Japanese White-eye (Zosterops japonicus), Northern Cardinal (Cardinalis cardinalis), and the Red-billed Leiothrix (Leiothrix lutea) were found in higher abundance than native species and they also were the first to recolonize following treatment. The most successful recolonizing species in the treated plots was the Japanese White-eye. Although endangered forest passerines were present in the adjacent control plot, they were not found in the treated plots. Seasonal differences in the number of birds detected in the treated plots were only observed for the native Apapane (Himatione sanguinea); it was found in high numbers following initial clearing, but subsequently declined, remaining stable through the study period.