Detecting declines in population size is one of the highest priorities of the shorebird initiatives in Canada and the United States. The quantitative goal is 80% power to detect a 50% decline, occurring during no more than 20 years, with a significance level of 0.15, using a two-tailed test, and incorporating effects of potential bias into the estimator. The Arctic PRISM program was designed to achieve this goal for arctic-nesting shorebird populations. The survey methods are an application of double sampling. Rapid surveys were made on a large number of plots selected from throughout arctic Alaska and Canada using stratified random sampling. Intensive surveys were made on a subsample of the plots to obtain detection rates, which were used to calibrate results from rapidly surveyed plots. Surveys will be made of the entire arctic region, each lasting several years and producing an estimate of average population size during the survey period. Results from two or more survey periods will be used to estimate change, or trend, in population size.
