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Citation. Sorenson, M. D. 1995. Evidence of conspecific nest parasitism and egg discrimination in the sora. The Condor 97:819-821. [1686 CC]
Introduction. Conspecific nest parasitism (CNP) is relatively frequent among precocial species and several hypotheses for this patter have been suggested (Rohwer and Freeman 1989, Lyon and Eadie 1991, Sorenson 1992). I report here observations made at the nest of a Sora, Porzana carolina, which suggest both the occurrence of CNP as well as very fine egg discrimination in this species. Recognition and rejection of parasitic eggs is a well documented defense in some hosts of obligate brood parasites (e.g., Rothstein 1975, Davies and Brook 1989) but may also evolve as a response to CNP (Freeman 1988; Jackson, in press). Intraspecific egg discrimination, however, has been verified in very few species (Arnold 1987). The following observations were made near Minnedosa, Manitoba, an area characterized by high densities of small wetlands and breeding waterfowl (see Kiel et al. 1972).
Keywords. Sora, Porzan carolina, conspecific nest parasitism, egg discrimination, egg rejection, Manitoba