A Parasite Survey of Passerine Birds and Northern Bobwhite Quail (Colinus virginianus) in the Rolling Plains Ecoregion

Eyeworms (Oxyspirura petrowi) and caecal worms (Aulonocephalus pennula) are heteroxenous nematodes being investigated as contributors to the decline of the Northern Bobwhite (Colinus virginianus; hereafter Bobwhite), an iconic game bird. Researchers have documented declines of over 4% annually across the range and declines in historic strongholds including the Rolling Plains of Texas. While climatic factors and habitat change were considered to be leading contributors, parasitic infection is gaining attention as a potentially important factor. Researchers have documented infection rates of eyeworms in Bobwhite as high as 90% and caecal worms as high as 100%. Furthermore, eyeworms have been documented in a Curve-billed Thrasher (Toxostoma curvirostre), Northern Mockingbirds (Mimus polyglottos), and Scaled Quail (Callipepla squamata) from the Rolling Plains. This is likely due to their diets, which include insect intermediate hosts of eyeworms. However, due to  extremely few comprehensive parasite studies concerning these species and previous passerine helminth reports being compiled from incidental bycatch, the extent of shared parasitism between quail and passerines in the Rolling Plains is unknown. Thus, the potential for passerines specifically to serve as reservoir hosts or means of dispersal to introduce parasites to naïve populations may currently be overlooked. To investigate this possibility and further document shared parasitism between passerines and quail, full parasite surveys on Bobwhite, Scaled Quail, Northern Mockingbirds, Curve-billed Thrashers, and Northern Cardinals (Cardinalis cardinalis) were conducted. Birds were trapped with baited double funnel traps at three study sites in the Rolling Plains from March to October 2019. After which, specimens were fully necropsied and both endo and ectoparasite prevalence were assessed. These assessments have demonstrated instances of coinfection, with one of the most prominent cohabitations occurring between eyeworms and lice across all species. In addition to this, data elicited from this survey contributes to broadening the current knowledge of parasitic infection concerning the study species. The findings of this study are a valuable baseline for future studies given the passerines’ potential to serve as reservoir hosts and disperse parasites.