RELATIONSHIPS BETWEEN THE GREAT SPOTTED CUCKOO CLAMATOR-GLANDARIUS AND ITS CORVID HOSTS IN A RECENTLY COLONIZED AREA

Near Granada, S Spain, great spotted cuckoos used 4 corvid species as hosts; in the magpie Pica pica the rate of parasitism was significantly higher than in other areas. Removal of host eggs by the parasite was never observed, but damaged eggs usually existed in parasitized nests and the most damaged ones were removed by the host. Frequently >1 cuckoo egg was laid per nest and sometimes clutches had eggs from >1 female. In experimental egg manipulations, rejection was found only in magpies. Eggs of the 4 host species are larger than those of the parasite but incubation was nevertheless effective. Size of cuckoo eggs did not vary significantly among different parasitized species, and their coloration was the same independently of host species and never mimetic (except for magpie). Fledging success of cuckoo was twice as high when it parasitized magpies as when it parasitized carrion crows Corvus corone. The 1st and 2nd parasite eggs were more successful than the 3rd, and the egg of a 2nd female parasitizing a nest had significantly lower hatching and breeding success than the 1st female's. Eggs deposited early in the laying period produced more chicks than those laid late and than those deposited when the clutch was completed. Cuckoo parasitism had little influence on the breeding success of carrion crow, but had a strong negative impact on that of the magpie. Differences in parasite adaptations of great spotted cuckoo and European cuckoo Cuculus canorus are discussed. -from Author