Taxonomic and Behavioral Components of Faunal Comparisons Over Time: The Bees (Hymenoptera: Anthophila) of Boulder County, Colorado, Past and Present

Abstract. Historical and recent studies of Boulder County, Colorado (USA) bees (Hymenoptera: Anthophila) illustrate the potential and the pitfalls of using comparative collection data to evaluate faunal composition and change over time. A compilation of bee records from Boulder County (Scott et al. 2011) is used as a basis for re-examining the comparison of an historical data set (Cockerell 1907) with a recent one (Kearns and Oliveras 2009a,b). Despite numerical comparability reported by Kearns and Oliveras, the taxonomic and behavioral composition of these data sets differ markedly from each other and, in different ways, from that of the subset of bee species common to both and from the total fauna documented from Boulder County. The rank order of species richness across bee families and across cohorts of bees with different social behaviors and feeding preferences do not covary among data sets: taxonomically, colletids, andrenids and megachilids are relatively under-represented in the more recent data s...