PUB - Publikationen an der Universität Bielefeld

Conspecific brood parasitism (CBP) brings the obvious fitness advantage of decreased breeding costs. However, the successful development of parasitic eggs depends on appropriate timing in relation to the host’s own eggs. A detailed documentation of CBP requires full knowledge of parentage.We achieved this in a captive population of zebra finches, Taeniopygia guttata, breeding in aviaries. The overall frequency of CBP was relatively high (21% of all host clutches, 5.4% of all eggs in host clutches) and comparable to what has been found in the wild in this species. A large proportion of paired females adopted a mixed strategy, laying one or two additional eggs in other nests before initiating their own clutches. Females showed a high individual consistency in whether they adopted a pure nonparasitic strategy or a mixed strategy, which is indicative of individual specialization. About 38% of all eggs laid outside a pair’s own nest were incubated by host pairs and can thus be considered successfully parasitic. No paired females were purely parasitic but unpaired females used CBP as a best of a bad job strategy. Hosts were targeted during the early phase of clutch initiation with the majority of parasitic eggs laid 0e5 days before the onset of incubation and usually before the host commenced egg laying. We did not find evidence that particular types of host females were targeted. The within-female repeatability of being a host was estimated to be negative. Overall, the systematic temporal patterns indicate targeted CBP behaviour in zebra finches.