Planning abundance estimation surveys when detectability is < 1.0

A common problem in wildlife censuses is that not all animals are detected during the search Resources may have to be allocated for estimating the pro bability of detection. The question may arise as to how much effort should be allocated to estimating detectability as opposed to conducting the censu s. Researchers planning abundance estimation surveys must sometimes choose between an intensive search of a small fraction of the study area and a les s intensive search of a larger area. I consider these problems ti om the st andpoint of minimizing the variance of the abundance estimator subject to c ost constraints. I also derive sample size formulas for simple random sampl ing and optimal allocation for stratified random sampling.