Patterns of association at feeder stations for Common Pheasants released into the wild: sexual segregation by space and time

摘要

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 fine-scale 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.