ABUNDANCE OF IRRAWADDY DOLPHINS (<i>ORCAELLA BREVIROSTRIS</i>) AND GANGES RIVER DOLPHINS (<i>PLATANISTA GANGETICA GANGETICA</i>) ESTIMATED USING CONCURRENT COUNTS MADE BY INDEPENDENT TEAMS IN WATERWAYS OF THE SUNDARBANS MANGROVE FOREST IN BANGLADESH

Abstract Independent observer teams made concurrent counts of Irrawaddy dolphins Orcaella brevirostris and Ganges River dolphins Platanista gangetica gangetica in mangrove channels of the Sundarbans Delta in Bangladesh. These counts were corrected for missed groups using mark‐recapture models. For Irrawaddy dolphins, a stratified Lincoln‐Petersen model, which incorporated group size and sighting conditions as covariates, and a Huggins conditional likelihood model, which averaged models that individually incorporated group size, sighting conditions, and channel width as covariates, generated abundance estimates of 397 individuals (CV = 10.2%) and 451 individuals (CV = 9.6%), respectively. For Ganges River dolphins, a stratified Lincoln‐Petersen model, which incorporated group size as a covariate, and a Huggins conditional likelihood model, which averaged the same models described above, generated…