Butcher, G.S.McCulloch, C.E.Sauer, J.R. and S. DroegeSurvey designs and statistical methods for the estimation of avian population trends.2010-02-152010-02-151990http://hdl.handle.net/1969.3/24712p. 120-129.No abstract availablesurveysInfluence of observer effort on the number of individual birds recorded on Christmas bird counts.Chapter