Fall diet in sharp-tailed grouse (Tympanuchus phasianellus jamesi) and consumption of the grasshopper Melanoplus dawsoni in Alberta, Canada

Abstract

Sharp-tailed grouse (Tympanuchus phasianellus) are an important component of northern grassland food webs, a reliable indicator species, and considered to be valuable to the preservation of biodiversity. Ecological stressors imposed on this species include habitat alteration, fragmentation, encroachment from agricultural development, insecticides, and the effects of climate change on prairie landscapes, all of which have the potential to alter food availability and trophic dynamics. Insects and spiders are an important food source for many grassland birds. The ecological roles of many arthropod species as prey and as contributors of other important ecosystem services remain relatively unexplored. This study examined esophageal crop contents from 164 plains sharp-tailed grouse (T. phasianellus jamesi) that were collected in 2017 and 2018 from three sites in southern and central Alberta, Canada. The remains of grasshoppers (Orthoptera: Acrididae, 18 species) were detected in 80% of esophageal crops collected in September, and 31% in October. Of the grasshopper samples, 91% and 63% respectively, were a single species identified as Dawson's grasshopper (Melanoplus dawsoni). Juvenile grouse consumed more grasshoppers than adult grouse in all cases. Studies on other gallinaceous game birds have also identified frequent consumption of single arthropod species, likely due to the range, catchability, and abundance of these species at certain times of year. This non-pest grasshopper species appears to form a significant part of the food supply for sharp-tailed grouse in the fall. Species-level arthropod ecology can contribute to a better understanding of ecosystem stability, optimal land management practices, and previously unexplored food web connections.