comparing efficiency of fixed-radius point count, variable-radius circular plot, fixed-width transect and variable -width transect methods to estimate richness and abundance for forest birds

hyrcanian forests in northern slope of alborz support high bird richness and abundance same as central of europe. in this study, efficiency of different methods including fixed-width transect, variable-width transect, fixed-radius point count and variable circular plot samplings were compared in order to present the most reliable methods for surveying and monitoring of diurnal forest birds in forested alborz mountains. three 1 km long transects and fifteen fixed and variable radius points which located 250m far from each other along the transects was performed. each transect and point was visited 3 times during august 2008. one-way anova was performed to analyze the data. the results revealed significant differences of bird richness and abundance between the points and transects sampling methods (f3,104=9.85, p=0.00 and f3,104=57.35, p=0.00 for bird richness and abundance respectively). in contrast, no significant differences in richness and abundance between variables and fixed transects as well as between fixed-radius point count and variable circular plot samplings were found. overall our results suggest transect method yielded greater bird richness and abundance than point count method, therefor, they can be more useful for preparation birds listing in forest ecosystems, but this also depends on habitat characteristics.