Do infections lead to higher feather mite loads in birds? A test with mycoplasmal conjunctivitis in House Finches (Haemorhous mexicanus)

Abstract

Abstract. Current evidence suggests that the health effect of avian feather mites is minimal. However, feather mites can still proliferate without effective preening, such as might occur during sickness. House Finches (Haemorhous mexicanus) are prone to infection by Mycoplasma gallisepticum, symptoms of which include conjunctivitis. Impaired vision and lethargy associated with the disease may limit preening ability. We examined trapping data from a 4-year study of Mycoplasma infection dynamics in House Finches in Atlanta, Georgia, to determine whether birds with conjunctivitis had higher feather mite loads. Abundance of feather mites (Proctophyllodes spp.) and conjunctivitis severity were visually scored on >800 House Finches of known age and sex. Feather mite abundance showed a distinct seasonal pattern: mite loads increased in July and remained high through January. Limiting the analyses to these months, we found that average mite scores were higher in birds with (n = 94) than in those without (n = 275)...