Differences in the ectoparasitic loads of Red knot in two wintering sites of South America

VERÓNICA L. D'AMICO, WALLACE R. TELLINO JUNIOR, ALLAN J. BAKER, PATRICIA GONZÁLEZ Y MARCELO BERTELLOTTI

Irlanda

Congreso; Wader Study Group 2005 Meeting; 2005

The diferences in the parasitic load between habitats and the diferences in the immunodefence investment between species, are basic elements to explain several pecularities of distribution patterns and migratory strategies of shorebirds.  In this study we analized the ectoparasitic load of Red knot, Calidris canutus rufa in its two wintering sites: Tierra del Fuego (Argentina) y Maranhao (Brazil). The birds were captured during November  2004 (Argentina) and February 2005 (Brazil). Parasitic loads were estimated as number of ectoparasites in a range between: 1-100, 101-200, 201-400 y > 400. Of the 113 individuals sampled in  Tierra del Fuego, only 5 showed ectoparasites, in a range of  1-100. All ectoparasites found in that site belonged to the Mallophaga order. On the other hand, all individual sampled in Maranhao (N=38) showed ectoparasites  of both orders, Mallophaga and Acari, but the majority of birds had ectparasites in a range > 400. The differences found in the ectoparasitic loads could be related to the enviromental characteristics of each wintering site. In general, the tropical zones (Maranhao) have a higher prevalnece of parasites, in comparison with the templates zones (Tierra del Fuego). The distance between both wintering sites (about 6000 km) and  the enviromental diferences could be affecting the Red knots conditioning, their migratory strategies.