Parasitismo de cría: nuevos eventos para el vaquero brilloso Molothrus bonariensis

Brood parasites lay their eggs in the nests of other species, thereby imposing on them the cost of parental care. In the Neotropics, the Shiny Cowbird Molothrus bonariensis is an obligate, generalist and opportunistic brood parasite with a wide and expanding range. This has led to an increase in the number of host species and potentially to fresh conservation problems. We searched for parasitic interactions in the Shiny Cowbird in Ecuador and documented 28 such events with 11 species. We added the Grey-browed Brush-finch Arremon assimilis and the Golden Grosbeak Pheucticus chrysogaster to the catalogue of previously known hosts (i.e., species that successfully raise the parasitic young). Additionally, we present here evidence of parasitism with the Eared Dove Zenaida auriculata, Fasciated Wren Campylorhynchus fasciatus, Thrush-like Wren C. turdinus and Tropical Mockingbird Mimus gilvus, which were previously listed only as victims (i.e., with no evidence of having successfully raised the parasitic young). We also increased the number of records of parasitism with the Peruvian Meadowlark Leistes bellicosus as a victim, and the Rufous-collared Sparrow Zonotrichia capensis, the Yellow-tailed Oriole Icterus mesomelas, the Scrub Blackbird Dives warczewiczi and the Silver-beaked Tanager Ramphocelus carbo as hosts. The Rufous-collared Sparrow seems to be the most commonly selected host in the Andean region of Ecuador. Although previously frequently recorded, many aspects of the natural history of this parasitic bird still need further research to preclude potential conservation problems in their host species.