Influence of black-tailed prairie dogs (Cynomys ludovicianus) on short-horned grasshoppers (Orthoptera: Acrididae) on the shortgrass steppe of Colorado

Abstract

Black-tailed prairie dogs (Cynomys ludovicianus; hereafter simply prairie dogs) strongly influence the structure and function of ecosystems, affecting several other species. Yet we know little about how arthropod populations respond to changes caused by prairie dogs. In this study, we examined the effects of black-tailed prairie dogs on the abundance and diversity of short-horned grasshoppers (Orthoptera: Acrididae) on the shortgrass steppe of the Pawnee National Grasslands in northeastern Colorado. We compared the abundance and diversity of grasshoppers on prairie dog colonies and comparable off-colony sites using hoop nets. We further sampled vegetation at all sites using Daubenmire frames. We captured significantly fewer grasshoppers on prairie dog colonies than on control plots. At the sub-family level, we found that prairie dog colonies supported significantly more grasshoppers in the sub-family Oedipodinae, while off-colony sites had a non-significant trend toward more Gomphocerinae grasshoppers. We found very similar mean site diversity (i.e., alpha diversity) on colony and off-colony sites, but relatively large differences in beta diversity (i.e., diversity across sites), suggesting that prairie dog colonies have an impact on short-horned grasshopper abundances and species composition on shortgrass steppe habitats.