Monitoring Bird Populations By Point Counts

Point counts of birds are the most widely used quantitative method and involve an observer recording birds from a single point for a standardized time period. In response to the need for standardization of methods to monitor bird populations by census, researchers met to present data from various investigations working under a wide variety of conditions, and to examine various aspects of point count methodology. Statistical aspects of sampling and analysis were discussed and applied to the objectives of point counts. The final chapter presents these standards and their applications to point count methodology.

Point counts of buds are the most widely used quantitative method and involve an observer recording buds from a single point for a standardized time period. In response to the need for standardization of methods to monitor bird populations by census, various investigators met in Maryland in late fall 1991 to evaluate point counts. Their objectives were to present data from various investigations working under a wide variety of conditions, and to examine various aspects of point count methodology. This volume contains the papers given at the workshop, as well as a few additional relevant papers that subsequently have been submitted to the technical coordinators. Statistical aspects of sampling and analysis were discussed and applied to the objectives of point counts. From this base, at interactive sessions the participants discussed and agreed upon standards of point counts that should have wide applicability to a variety of habitats and terrain. The final chapter presents these standards and their applications to point count methodology. Forest Service, US Department of Agriculture

Minute-by-minute analysis of point counts of birds in mixed-conifer forests in the Sierra National Forest, central California, showed that cumulative counts of species and individuals increased in a curvilinear fashion but did not reach asymptotes after 10 minutes of counting. Comparison of the expected number of individuals counted per hour with various combinations of counting time and noncounting times for record keeping and travel between counting stations showed that 10-minute counts were most efficient in most cases. Counting longer than 10 minutes is not recommended, because other increased risk of double counting some individuals.

Presents a compilation of methods that can be used to assay population size, demographics, & status of virtually all species of landbirds in a wide variety of habitats. Suggests priorities for selecting a monitoring method & determining station location. Presents general tasks that determine which species can be monitored, & methods of establishing & maintaining a study plot, journal keeping, & training of personnel. Describes two demographic methods & four types of censuses for determining population size & trends. Methods are suggested for measuring habitat, recording weather, & color banding. Illustrated.