Our manuscript about the long-term effects of an intestinal parasite (Isospora coccidian) on moult schedule and feather quality has now a “major revision” decision in the Biological Journal of the Linnean Society. Parasite’s effect on host reproduction has received considerable attention, but surprisingly little is known about the effects of parasites on moult and feather quality, despite feather functionality deeply influences lifetime fitness. Intestinal parasites are good candidates for mediating plumage aspects because they divert vital resources directly from host’s alimentary tube when the protein exigencies of feather production are the highest. We manipulated parasite levels (medicated vs control group) of adult male and female house sparrows throughout 15 months spanning two natural moulting periods. Although coccidians had no effect on moult initiation and pattern, medicated birds developed consistently higher quality feathers regarding several feather traits. Some feather aspects were affected only at long-term (i.e. no effect during the first moult, but marked effect during the second). We stress the importance of long-term studies / experiments especially in case of parasites that infest their hosts throughout their lifespan. Bold face names below indicate authors financed by a CNCSIS grant (#TE291/2010).
Pap PL, Vágási CI, Bărbos L and Marton A. Chronic coccidian infestation compromises flight feather quality in house sparrows, Passer domesticus.