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Should a female copy the mate choice of other females? A female may rank a mated male higher in quality than an unmated male because the former has demonstrated that he is able to attract a female. However, a prospecting female may also avoid a mated male because of the risk that she has to compete with the male's initial mate over access to copulations, breeding resources and male parental care. We studied the mate choice of female pied flycatchers Ficedula hypoleuca, in aviaries divided into three compartments, two for males, and one for a female. A female was allowed to choose (build a nest in a nestbox) between two males after a period when she had been kept in a cage behind a one-way mirror and had presumably seen that one of the males was in the company of another female for 5 h. There was no evidence that females copied the mate choice of conspecific females, or that they avoided males that had recently been in the company of another female. Instead, females apparently chose a mate independently of others, choosing the male showing most courtship display. The latter result explains the consistency in mate choice observed when different females chose between the same pair of males in repeat trials. The ability of females to pick out the same male independently may also explain why a few males obtain most copulations in lekking species. Copyright 1999 The Association for the Study of Animal Behaviour.

The question of whether, and how, male birds should change their parental effort in response to reduced paternity is a controversial issue among behavioural ecologists. We report a study on pied flycatchers, Ficedula hypoleuca, in which paternity was manipulated through experimentally induced mate switching during the female's fertile period. The paternity of care-giving males ranged from 0 to 100% of the brood. The number of parental males per nest varied between zero and two, and the amount of male assistance in nestling provisioning had a marked effect on female reproductive success. For 17 monogamous males, provisioning effort and the body mass of nestlings on day 12 were reduced at low levels of paternity. However, the shape of the effort function was not unambiguously determined. Male provisioning effort showed a curvilinear decline, whereas nestling body mass showed a linear decline. Two important assumptions of the theory of optimal parental effort seem to be fulfilled in this case: that males had reliable cues to their paternity, and that paternity is likely to be increased in future (normal) breeding attempts. The fact that males reduced their effort at the expense of the welfare of the offspring suggests that there are significant costs of parental care in this species. Whether a similar response to cuckoldry occurs in unmanipulated breeding situations remains to be studied.Copyright 1998 The Association for the Study of Animal Behaviour.

In some altricial birds with biparental care, it is the female, and in others the male, that provides more food to the smallest offspring within the brood. Many hypotheses have been proposed to account for such puzzling patterns of parental care. A parsimonious explanation is that no difference exists between the parents in priority of care but that differences arise simply from sibling rivalry, with dominant chicks trying to position themselves closest to the parent that provides most care (the sibling rivalry hypothesis). A refinement of the idea is that parents use the way they approach the chicks to counter selfish offspring and in this way control allocation of care (the parental approaching hypothesis). A comparison across species suggested that female care of the smallest chick within a brood is the ancestral and most common pattern. However, strong variation exists within single populations. In one species, the American robin, Turdus migratorius the sibling rivalry hypothesis and the parental approaching hypothesis were both supported because in broods where males provided more care than females, the largest chick was predominantly fed by the male whereas the smallest chick was predominantly fed by the female. When the male provided less care than the female, an opposite result was found. The same patterns of allocation of care also seemed to exist when chicks were quite immobile just after having left the nest and when their positions were experimentally controlled, suggesting parental control.Copyright 1997 The Association for the Study of Animal BehaviourCopyright 1997The Association for the Study of Animal Behaviour.

By making female birds pair successively with different males, and analysing the paternity of the eggs laid, it is possible to examine how a male's success in obtaining fertilizations is determined by the timing of his copulatory access to the female. Such an experiment is reported here with pied flycatchers, Ficedula hypoleucaMate switching was induced at different stages within the female's fertile period by removing the resident male. The paternity of the clutch was analysed by microsatellite DNA typing. Removed males had full paternity in the clutch if they were removed as late as after the second egg was laid (day 1), and they lost all paternity if they were removed more than 1 day before the first egg was fertilized (less than day -2). Male switching during the period day -2 to day 1 always resulted in mixed paternity in the clutch. Males that were paired to the female for only a few (1-3) days during this period achieved on average more than one fertilization per access day, with a peak on day -1. Thus, assuming that the timing of observed pair bonds reflects the timing of each male's copulatory access to the female, the first eggs in the laying sequence were fertilized by inseminations occurring shortly before the time of fertilization, whereas the last eggs were fertilized by inseminations taking place several days prior to their fertilization. Our documentation of the most important period for copulatory access has some important implications for understanding sexual behaviour in this species.