The Prevalence of Coccidian Parasites in Passerine Birds from South America

Fecal samples were collected from 655 passerine birds representing 190 species from 13 collection sites in Guyana, Ecuador, Peru, and Argentina from August, 1990 August, 1997. The fecal samples were stored in 2.5% K2Cr2O7 and examined for coccidian oocysts within six weeks after collection. The overall prevalence of coccidian parasites in the samples was 20.9% (137/655). The one-sample test of equality of proportions was applied to the prevalence data comparing host behavior, habitat, and diet to the overall coccidial prevalence. Host behavior was divided into five groups according to the bird’s gregariousness with other birds. Solitary foragers or birds that forage in pairs had significantly lower coccidia prevalence (12.6% and 1.0% respectively) than the overall average. More gregarious birds that spend approximately equal amounts of time with other birds in pairs or in flocks had higher prevalence of coccidial parasites. Birds that forage alone or as couples (single-pairs) and birds that are periodically social foragers (single-pairs-flocks) were significantly higher than the overall average with 39.1% and 42.9% respectively. Birds that forage in couples or flocks (pairs-flocks) were sightly below average with 16.0% parasite prevalence. Forest dwellers and ground feeders (22.5% and 23% respectively) had parasite infection rates near the overall average while canopy and forest border dwellers had significantly lower parasite prevalence (13.4% and 8.7% respectively). Pertaining to diet, fruit eaters showed a significant lack of coccidia with a one percent infection rate compared to a 22.8% for ground insect and 28.5% for bark and leaf insect eaters. A profile of the wedge-billed woodcreeper (Glyphorynchus spirurus) was used as an example of a passerine species with a high prevalence of coccidian parasites.