Sex specific survival in the southern anteater-chat Mymecocichla formicivora.
(English)Manuscript (preprint) (Other academic)
Survival is a key factor behind life-history variation both between and within species. It is also a major influence on sociality in species which delay dispersal and live in family groups. Knowledge of differential survival rates between males and females and juveniles and adults give insights into the costs and benefits of different behavioural and life-history strategies. Here we investigate patterns of survival in a population of the southern anteater-chat (Myrmecocichla formicivora), a facultative cooperatively breeding passerine of southern Africa. Using data from a 9-year mark-capture-recapture study, we examined juvenile and adult sex related variation in survival, and the role of environmental variables (rainfall, temperature) for survival patterns in the population. Annual adult survival probability (mean ± SE) was 0.71 ± 0.03 for males and 0.60 ± 0.04 for females. Juvenile survival was lower for each sex, with juvenile female survival (0.36 ± 0.04) being 35% lower than juvenile male survival (0.55 ± 0.04). Using these estimates we calculated the mean life span (MLS) in years for male southern anteater-chat to be 4.0 ± 0.7, considerably higher than for females at 2.0 ± 0.4. These figures closely matched the population-age structure of the study area, and could explain the high male biased sex skew of adult birds in this population. Higher annual mean temperature was associated with higher survival, whereas higher annual rainfall was associated with lower survival for both sex and age classes. Female survival, particularly female juvenile survival, may be reduced due to prompt dispersal and longer dispersal distances, and the additional costs of breeding early in life. Differential survival can promote male philopatry and this in turn could well encourage the cooperative breeding we see in the southern anteater-chat.
Southern anteater-chat, cooperative breeding, social evolution, behavioural ecology, delayed dispersal, family living, Africa
Research subject Biology with specialization in Population Biology
IdentifiersURN: urn:nbn:se:uu:diva-179072OAI: oai:DiVA.org:uu-179072DiVA: diva2:544039