Species composition and absolute population density of breeding birds obtained by two methods

Abstract

John Emlen in 1971 (Auk 88:323-341.) explained details of a new technique for determination of bird population densities involving a transect or strip-census count. From this count, using previously established coefficients of detectability, absolute population densities can be determined. The Emlen technique is applicable in summer and winter while necessitating proportionately fewer man-hours in the field than comparable methods. This study was an evaluation of the technique by comparing it with the territorial mapping method. The study was conducted in the upland beech-maple woods at The University of Wisconsin-Milwaukee Field Station. Twelve censuses each year were taken from June 28 to July 28 in 1972 and from June 2 to July 11 in 1973. Each census began after sunrise (after 0500 hours C.D.T.) and lasted 3 to 4 hours.