004810000a2200157000450024501140000065000090011465000260012365000150014965000150016465000180017965000110019765100270020804100130023510000220024877300530027010aEffect of time of day and time of season on the number of observations and density estimaes of breeding birds14aAves14aPatrones de actividad14aEtología14aEstaciones14aOrnitología14aCensos 4dOregonpEstados Unidos0 aInglés1 aSkirvin, Aaron A.1 tStudies in Avian Biology31194h6q271-274d1981