Factors Affecting the Efficiency of the Area Search Method of Censusing Birds in Open Forests and Woodlands

Abstract

SummaryThis paper examines factors that influence the ability of area searches to census the complete bird population at a site. Such factors included duration and repetition of census periods, density of vegetation, density of individuals of species, weather and time of day. Total time spent on the site was found to be more important than the duration or the number of repetitions of the census period, especially in sites with a dense understorey. In sites with a sparse under-storey, more repetitions of censuses of short duration were more effective. To obtain a complete species list, a total time of around 100 census minutes was required in sparse sites compared with 150 minutes in dense sites. Birds occurring at high density were not necessarily encountered early in the censusing, probably due to their mobility. Increasing wind strength, time after sunrise and minimum temperature adversely affected the number of species found.