Age-based Nest-site Selection And Reproductive Success In The Yellow-rumped Flycatcher(Ficedula Zanthopygia)

Age is often used to explain the reproductive differences at different stages of the life cycle of birds.However,small birds have a short lifespan and are susceptible to factors such as dispersal,which makes it difficult to tag and track them,leading to few age-related studies.The team had previously tagged and track adult and fledgling yellow-rumped flycatcher using banding for many years,and found that they were habitat faithful and the same tagged individuals were recaptured several times.From March to July,2019 to 2020,the yellow-rumped flycatcher in Zuojia Nature Reserve were selected as the research objects.Based on the previous data within the group,the number of recapture was taken as the relative age,and the yellow-rumped flycatcher were divided into three age groups:first,second and above the second age.From nest characteristics,social information utilization,brooding behavior and reproductive success rate,the effects of age on the selection of nest sites and reproduction were studied.The main findings are as follows:Age factors affect nest site selection.Age factors have a significant effect on nest entrance size(GLMMs,?~2=5.379,P=0.020),and individuals of above the second age choose a smaller nest entrance,which is conducive to improving nest safety.Age factors had no significant effect on the direction and inclination of the nest entrance,but preferred to choose the nest with the downward inclination angle and avoid the northwest direction of the nest entrance,which was related to preventing rain from entering the nest.At the same time,it is helpful for it to better adapt to the local climate and maintain the microclimate in the nest.Age factors has a significant effect on the selection of the number of heterogeneous species around the breeding nest(GLMMs,?~2=6.889,P=0.009),suggesting that time saving may be achieved by using the social information of the heterogeneous species in the nest selection process.Age has a significant influence on the selection of nest density around the nest(GLMMs,?~2=46.588,P<0.001).The yellow-rumped flycatcher is obviously inclined to nest in the area with higher nest density.Higher nest density can enhance the colony defense and dilute the risk of predation.Age factors had no significant effect on reproductive success,that is,there were no significant differences in clutch size,fledglings,reproductive success rate,sex ratio of offspring and body condition of fledglings in different age groups.However,the nesting time of individuals of above the second age the shorter,it may be related to the higher nest security.Moreover,the older individuals have more experience in raising young,which can reduce the probability of being discovered by predators due to frequent nesting.The results of this study provide a theoretical basis for investigating the nesting site selection patterns and reproductive outcomes of short-lived birds from the perspective of age factors.