The feasibility of using distance sampling method to estimate Pheasant (Phasianus colchicus) population in Sa ad Abad Forest, Gorgan

Population management of exploited species requires information on absolute density and abundance through reliable survey methods. The baseline information is further needed for population dynamics studies and determination of conservation status. The current population size of pheasant is totally unknown, because there is no official attempt to estimate population size in previous years. In this study, line transect based Distance Sampling method was used to yield population estimates in Sa’ad Abad Forest. Data from aural and visual counts were combined to calculate overall estimates. Adjustment was made in which an aural detection was assumed to represent four birds per flock. Otherwise, the estimates were found to be underestimated. Results indicated that an unbiased estimation of overall density and abundance of pheasant for the entire 4000 ha study area, D ± S.E. = 0.35 ± 0.070 birds/ha and N ± S.E. = 1400 ± 280 birds, respectively. The cluster size of the species was estimated at, E(s) ± S.E. = 2.143 ± 0.139 birds/flock.