A comparison of estimates of relative abundance from a weakly structured mass-participation bird atlas survey and a robustly designed monitoring scheme

摘要: Estimates of population size are frequently used in conservation. Volunteer-conducted surveys often the only source information available, but their reliability is unclear. We compare data from a weakly structured national bird atlas collected by volunteer surveyors free to choose where and when visit with an independent suite monitoring that stratified sampling design. focus on Mount Lofty Ranges, South Australia, region has lost most its native vegetation. Both datasets comprise several thousand 20-min 2-ha searches carried out between 1999 2007. The dataset reported more species, covered habitats comprehensively, showed greater variability temporal spatial distribution survey effort. However, after we restricted eucalypt woodlands, reporting rates two schemes were very strongly correlated. tended record species normally detected call unstructured recorded using edges open habitats. Minimum estimates agreed well. strength concordance depended whether overflying birds included, highlighting importance distinguishing such records future surveys. conclude appropriate calibration selected regional surveys, including estimate absolute densities, can enable volunteercollected be generate robust occupancy minimum for many at scale.