Sexual segregation is common and can occur when sexes occupy different habitats, and/ or when sexes aggregate assortatively within the same habitats. However, it is rarely studied in birds, with most previous work concentrating on differential settlement by the sexes in discrete habitats, often separated by large distances. Little attention has been paid to patterns of segregation within the same site. We reared 200 Common Pheasants Phasianus colchicus and released them onto a relatively small site of 250 ha and recorded their patterns of association and differential use of artificial feeders in space and time. Particular feeders were preferred by one sex, although we found no features of the local habitat which explained such preferences. Furthermore, we found sex differences in the use of feeders throughout the day, with females preferentially visiting them in the morning and the proportion of females visiting feeders increasing as the year progressed. Social network analyses found that in the first month after release into the wild, females did not associate strongly with other females, which was surprising as, prior to release, females have been shown to associate with other females in both semi-natural conditions and when tested in isolation. However, sexual segregation was clearly seen after 1 month of being released and became more pronounced as the year progressed. Females associated with other females from November to February, whereas males avoided other males over this same period. Sexes became less likely to associate with one another in 5 of the 6 months monitored. Such avoidance observed in males suggests that they start to form territories much sooner than previously thought. Pheasants exhibit clear patterns of finescale sexual segregation based on space and time, which was observed in their social preferences at feeding sites. Such detailed fine-scale segregation is rarely observed in birds.
Memories about the spatial environment, such as the locations of foraging patches, are expected to affect how individuals move around the landscape. However, individuals differ in the ability to remember spatial locations (spatial cognitive ability) and evidence is growing that these inter-individual differences influence a range of fitness proxies. Yet empirical evaluations directly linking inter-individual variation in spatial cognitive ability and the development and structure of movement paths are lacking. We assessed the performance of young pheasants ( Phasianus colchicus ) on a spatial cognition task before releasing them into a novel, rural landscape and tracking their movements. We quantified changes in the straightness and speed of their transitory paths over one month. Birds with better performances on the task initially made slower transitory paths than poor performers but by the end of the month, there was no difference in speed. In general, birds increased the straightness of their path over time, indicating improved efficiency independent of speed, but this was not related to performance on the cognitive task. We suggest that initial slow movements may facilitate more detailed information gathering by better performers and indicates a potential link between an individual's spatial cognitive ability and their movement behaviour.
The recent decline in farmland songbirds in the UK has coincided with increases in the populations of many nest predators. However, studies which have removed nest predators and monitored the response of prey populations have found mixed results. One explanation for this ambiguity is that, within species, predators differ in how likely they are to predate nests and only the removal of particularly predatory individuals will improve the breeding success of prey populations. Predators could differ in the extent to which they take nests due to variation in the local environment and/or variation within the predator population, e.g. differences in breeding status. Additional to these broad factors, certain individuals may specialise on particular prey. We placed 460 artificial nests in a systematically balanced design in UK farmland to analyse these sources of variation in predation. Magpies (Pica pica) were the most common predators of our artificial nests and the vulnerability of our nests to magpie predation varied according to magpie breeding status (predation was higher inside breeding magpies' territories), but this effect varied temporally. More nests were predated inside of magpie territories late in the season, when magpies had dependent fledglings. More specifically, some nest locations were especially vulnerable independent of both magpie breeding status and time in breeding season. These nests may have been disproportionately predated by specific, particularly predatory, territorial magpies. Habitat management and/or predator removal may benefit songbird populations if targeted towards reducing the effect of particular individuals identified as more likely to predate songbird nests.
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