GENERALIZED MARK-SIGHT POPULATION-SIZE ESTIMATION APPLIED TO COLORADOMOOSE

A new procedure for constructing confidence interval estimates of popu lation size in mark-sight experiments is presented. The method of sele cting animals for marking must be equivalent to a simple random sample without replacement. Marked animals are required to be individually i dentifiable. The number of times animals are sighted must be independe nt of their mark status. The sighting process does not need to be comp osed of independent sighting trials or even decomposable into separate trials. Sighting probabilities can vary among individuals and can dep end on such factors as group size and vegetational cover. Other method s of constructing confidence intervals in mark-sight experiments given these latter conditions have failed to achieve their stated nominal c onfidence level. Our confidence interval procedures are shown by simul ation to have actual confidence levels close to nominal under conditio ns encountered in an application to a Colorado moose (Alces alces shir asi) population. For this population with 29 radio-collared moose and 5 helicopter sighting nights, the 90% confidence interval for the moos e population size on the 1,400-km(2) area was 382-505.