SIZE-DEPENDENT VARIATION IN REPRODUCTIVE SUCCESS OF A LONG-LIVED SEABIRD, THE ANTARCTIC PETREL (THALASSOICA-ANTARCTICA)

We examined how variation in parental quality influences the reproduct ive success of a long-lived seabird, the Antarctic Petrel (Thalassoica antarctica). In particular, we focused on how quality of parents can interact with and influence the effects of stochastic variation in the environment due to varying climatic conditions. Large annual variatio n was found in reproductive success. However, body mass of individual chicks at the end and beginning of the nestling period was strongly co rrelated in two of the study years, suggesting consistent variation am ong parents in their ability to feed offspring. Furthermore, chick mas s was related both to overall body size and to body mass of their pare nts. Short brooding-shift intervals also were important for growth and survival of chicks. The probability of chick survival to the age of 3 0 days (ca. two weeks before fledging) was strongly correlated with ch ick mass when the chick was left unattended. However, the relative imp ortance of different parental characteristics differed between years. These results show that reproductive success of the Antarctic Petrel i s influenced by stochastic variation in the environment, probably rela ted to climatic conditions. Effects of this stochastic variation may d epend on body mass and/or body condition of the parents.