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Parental care is a costly behaviour that raises the prospects of offspring survival. In species with biparental care these costs are shared by both parents, although there may be a conflict regarding the relative investment of each sex. Avian brood parasites leave all the costs of rearing offspring to their hosts. The magnitude of these costs and their consequences on the relative role of both sexes in parental care and future reproduction remain mostly unknown. Here, we investigate whether provisioning rate of nestlings by magpie hosts Pica pica differs between broods parasitized by the great spotted cuckoo Clamator glandarius and non‐parasitized broods, and whether the relative contribution of each sex to provisioning is affected by parasitism. Furthermore, we explore the effect of parasitism on magpie's future reproduction. We found that provisioning rate was similar in parasitized and non‐parasitized broods, and that the relative contribution of males and females was also similar, irrespectively of the parasitism status. However, rearing parasitic offspring seems to have a negative long‐term effect on magpie's breeding phenology in the following breeding season. Our results suggest that, although brood parasitism by great spotted cuckoos does not seem to influence the relative contribution of both sexes to parental care, it may entail long‐term extra costs in terms of breeding delay for magpies. [ABSTRACT FROM AUTHOR] more...

When the strength or nature of a host-parasite interaction changes over the host life cycle, the consequences of parasitism can depend on host population age structure. Avian brood parasites reduce hosts' breeding success, and host age may play a role in this interaction if younger hosts are more likely parasitized and/or less able to defend themselves. We analyzed whether the age of female magpie (Pica pica) hosts is associated with parasite attack or their ability to reject foreign eggs. We recorded parasitism and model egg rejection of known-age individuals over their lifetime and established whether the likelihood of parasitism or egg rejection changed with age or longevity. Parasitism probability did not change with female age, and there was a trend toward longer-lived females being less likely to be parasitized. However, model egg rejection probability increased with age for each individual female, and longer-lived females were more prone to reject model eggs. Most females in the population were young, and the majority of them accepted model eggs, suggesting that brood parasites exploiting younger host individuals are benefitting from a lower defense level of their hosts. Our results stress that the intensity of selection by brood parasites may be mediated by the age structure of host populations, a to-date neglected aspect in brood parasite–host research. [ABSTRACT FROM AUTHOR] more...

The study of mechanisms underlying host selection by brood parasites usually lays on selection by parasites of host traits that inform on host parental abilities or location. However, brood parasites might use information extracted from past reproductive performance of either their hosts or themselves, a possibility almost neglected. In this study, we use a long-term data set to analyze whether the probability of parasitism by great spotted cuckoos (Clamator glandarius) of a magpie (Pica pica) [ABSTRACT FROM AUTHOR] more...

Environmental characteristics of neighboring locations are generally more similar than those of distant locations. Selection pressures due to parasitism and other environmental conditions shape life history traits of hosts; thus, the probability of parasitism should be associated with the strength of spatial autocorrelation in life history and defensive traits of their hosts. Here we test this hypothesis in three different subpopulations of Magpie (Pica pica) parasitized by the Great Spotted Cuckoo (Clamator glandarius) during three breeding seasons. In some of the years and study plots, we found evidence of positive spatial autocorrelations for clutch size and parasitism rate, but not for laying date. As predicted, brood parasitism was associated with the strength of these spatial autocorrelations. Magpies that bred close to each other in areas of high risk of parasitism responded similarly to experimental parasitic eggs. Moreover, an elevated risk of parasitism eliminated the spatial autocorrelation for clutch size, which became randomly distributed. We discuss possible mechanisms explaining these associations, which may have important consequences for estimating evolutionary responses of hosts to parasitic infections and, therefore, for epidemiological, ecological, and evolutionary studies of host-parasite relationships. [ABSTRACT FROM AUTHOR] more...

Understanding the causes and consequences of avian dispersal is important since dispersal movements may influence individuals’ survival and reproductive success. Although obligate interspecific brood parasitism has obvious detrimental effects for its avian host, few empirical studies have addressed the question of how brood parasitism may influence host dispersal. We studied factors affecting, and consequences of, natal and breeding dispersal movements in a population of magpies, Pica pica, parasitized by the great spotted cuckoo, Clamator glandarius, by monitoring dispersal of individuals and cuckoo parasitism over 6 years. Recruitment probability increased with fledging weight and was higher for individuals hatching early in the breeding season. Heaviest recruits at fledging settled closer to their natal nests and bred in more saturated sites within the study area. Natal dispersal distance did not predict the magpie’s productivity or risk of cuckoo parasitism in its first reproductive attempt. Females and parasitized males decreased their breeding dispersal distance when breeding close to other pairs, whereas nonparasitized males breeding close to other pairs dispersed more in subsequent years. Females, but not males, breeding closer to their previous breeding places had larger clutches than those breeding further away. Dispersing longer or shorter distances between breeding attempts had no consequences in terms of cuckoo parasitism avoidance for magpies. Our results suggest a minor role of great spotted cuckoo parasitism on magpie dispersal movements at the spatial scale analysed. Instead, our study revealed density-dependent dispersal in our parasitized magpie population. [Copyright &y& Elsevier] more...