Variations in growth of Cape petrel Daption capense chicks

Authors

  • Karel Weidinger

    1. Department of Zoology, Charles University, Viničá 7, CZ-I28 44 Praha 2, Czech Republic
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    • *Laboratory of Ornithology, Palackf University, d. Svobody 26, CZ-771 46 Olomouc, Czech Republic


Abstract

This study reports on the growth of Cape petrel chicks at Nelson Island, South Shetland Islands, Antarctica, during the breeding seasons 1990/91 and 1991/92. Parameters of logistic growth model fitted to mass, wing, culmen and tarsus measurements were compared between available composite data sets. Differential growth rate of morphometric characters and their proportional development at hatching and fledging conform to the pattern observed in other fulmarine petrels, overall growth rate being among the fastest found in Procellariiformes. Composite growth curves varied significantly between populations, but few annual, seasonal, and intercolony differences were found within the Nelson Island population. As the differences between chicks from equally disturbed colonies were less marked than in comparison with the control colony, regular handling most probably reduced the growth in this study. Larger eggs produced heavier rather than structurally larger hatchlings, which attained higher peak and fledging mass and size. Strength of the relationship between egg-size and chick measurements initially declined with chick age but, in contrast with results of earlier studies, increased again after around the middle of the chick-rearing period. This suggests that pre-hatching maternal factors probably influenced initial and fledging (peak) size and mass of chicks via egg-size, while intermediate stages of growth were less affected. A difference in mass between chicks from small and large eggs was maintained until fledging and increased gradually until peak mass was reached.

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