VARIATIONS IN GROWTH OF CAPE PETREL DAPTION CAPENSE CHICKS

This study reports on the growth of Cape petrel chicks at Nelson Islan d, South Shetland Islands, Antarctica, during the breeding seasons 199 0/91 and 1991/92. Parameters of logistic growth model fitted to mass, wing, culmen and tarsus measurements were compared between available c omposite data sets. Differential growth rate of morphometric character s and their proportional development at hatching and fledging conform to the pattern observed in other fulmarine petrels, overall growth rat e being among the fastest found in Procellariiformes. Composite growth curves varied significantly between populations, but few annual, seas onal, and intercolony differences were found within the Nelson Island population. As the differences between chicks from equally disturbed c olonies were less marked than in comparison with the control colony, r egular handling most probably reduced the growth in this study. Larger eggs produced heavier rather than structurally larger hatchlings, whi ch attained higher peak and hedging mass and size. Strength of the rel ationship between egg-size and chick measurements initially declined w ith chick age but, in contrast with results of earlier studies, increa sed again after around the middle of the chick-rearing period. This su ggests that pre-hatching maternal factors probably influenced initial and hedging (peak) size and mass of chicks via egg-size, while interme diate stages of growth were less affected. A difference in mass betwee n chicks from small and large eggs was maintained until fledging and i ncreased gradually until peak mass was reached.