EGG RECOGNITION IN YELLOW-BILLED AND BLACK-BILLED MAGPIES IN THE ABSENCE OF INTERSPECIFIC PARASITISM: IMPLICATIONS FOR PARASITE-HOST COEVOLUTION

Abstract

Abstract Yellow-billed Magpies (Pica nuttalli) ejected 100% of nonmimetic eggs placed in their nests despite such behavior having no detectable present day benefits. They are not currently parasitized, nor is there any evidence of a recently extinct brood parasite. Furthermore, there was no molecular evidence of conspecific parasitism, and Yellow-billed Magpies accepted eight of nine conspecific eggs transferred between nests, so recognition would rarely be of benefit if conspecific parasitism occurred. Thus, we suggest that egg recognition in Yellow-billed Magpies is a plesiomorphic trait, a primitive character inherited from a remote ancestor, its nearest relative, the Black-billed Magpie (Pica pica). The latter suffers from parasitism by Great Spotted Cuckoos (Clamator glandarius) in Eurasia and displays rejection behavior throughout Europe in populations that are allopatric and sympatric with this cuckoo. As would be expected if Yellow-billed Magpies inherited rejection behavior from the Black-billed ...