Keywords
Mimus saturninus
Abstract
The host-parasite interactions between Chalk-browed Mockingbirds (Mimus saturninus) and Shiny Cowbirds (Molothrus bonariensis) were studied around Villa María, Córdoba, Argentina, between 1979–1984. The incidence of parasitism was 81/92 or 88.04%. Mockingbirds in the study site accepted Cowbird eggs, even those of the immaculate morph, which are rejected in Buenos Aires. Incubation period for the host was 14–15 days, for the parasite 12–13 days, with nestling periods of 13–14 and 14–15 days respectively. Breeding season of host and parasite overlapped almost completely. In a better-studied subsample of parasitized nests, success for the host was 7.70% (ratio fledglings/eggs of 3/39) and for the parasite 6.45% (2/31). Cowbirds punctured and removed host eggs. Mockingbirds were probably the best local hosts for the Cowbirds
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