Egg Temperature, Embryonic Metabolism, and Water Loss from the Eggs of Subantarctic Procellariiformes

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Abstract
Egg temperatures, embryonic metabolism, and water loss from the eggs of two large surface-nesting and three small burrow-nesting Procellariiformes from high latitude were measured for comparison with tropical species of the order. Egg temperatures, measured using blown eggs of the respective species containing transmitters, averaged 32.0 C, slightly lower than that reported for most tropical Procellariiformes. However, the difference appears to be related to different methods used to measure egg temperature rather than to differences related to geographical distribution. Mean daily rates of water loss ranged from 1,062 mg day⁻¹ for the large wandering albatross to 117 mg day⁻¹ for the very much smaller Salvin's prion and were comparable to water loss rates from similarly sized eggs of tropical species. Embryonic oxygen consumption increased throughout incubation and prepipping levels ranged from 1,698 ml O₂ day⁻¹ for wandering albatross to 221 ml O₂ day⁻¹ for Salvin's prions, similar to that of tropical species with similarly sized eggs. However, total oxygen consumed by embryos over the entire incubation period was higher in high-latitude Procellariiformes than in their tropical counterparts as a result of elevated pip-to-hatch and hatchling oxygen consumptions. Elevated hatchling oxygen consumptions may be related to higher thermoregulatory demands of chicks of Procellariiformes reared at high latitudes.