Physiological Adaptation and Phylogenetic Constraints on Reproduction in Antarctic Birds

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The adults of many species of Antarctic birds show morphological, physiological and behavioral adaptations to their cold environment. However, it is not known how adults and chicks have adapted to enable successful chick survival and growth under Antarctic conditions. The thermoregulatory problems facing nestling birds are tremendous due to their immature physiology, small size, poor insulation and lack of mobility. The development of endothermy is a crucial event during the ontogeny of young birds, and it profoundly impacts the energetics and reproduction of their parents. Bennett will investigate whether thermoregulation of young chicks is primarily influenced by behavior of adults and chicks or the physiological capacity of the developing young, using three charadriiform bird species (Kelp Gull, Antarctic Skua, and Greater Sheathbill). These birds independently colonized Antarctica and are hence ecologically convergent. The Kelp Gull range extends to lower latitudes, enabling comparisons to be made both within and between species. The relative energetic costs and survival implications of different behavioral strategies (including nest construction, foraging patterns and brooding behavior) and physiological adaptations (including resting and maximal oxygen consumption, conductance, shivering capacity, and enzymatic activity in skeletal muscles) will be assessed. This study will form a critical part of a larger study of the evolution of development in charadriiform birds in response to ecological pressures.