The Effect of Responsive Movement on Abundance Estimation Using Line Transect Sampling

SUMMARY Line transect estimators of abundance are biased when responsive movement in relation to the transect line occurs. We present and compare two approaches to correct estimators with auxiliary information on movement: a correction factor approach and a decomposition approach. Movement and detection of animals were simulated by computer. The decomposition approach is preferred over the correction factor approach. The methods are illustrated with survey data of Dall's porpoise in the Gulf of Alaska.