Intraclutch Variation in Egg Conductance Facilitates Hatching Synchrony of Canada Geese

[摘要] Abstract. In many avian species with synchronously hatching young, incubation and embryonic development begin prior to the completion of the clutch. However, mechanisms regulating synchronous hatching and more rapid embryonic development in eggs laid later in the clutch are poorly understood. We measured physical characteristics of eggs from complete clutches of Canada Geese (Branta canadensis) to investigate whether variation in eggshell conductance, shell thickness, shell porosity, or rates of yolk accumulation during egg formation might support the observed increase in metabolic rate of eggs laid later. Canada Geese lay large clutches (7–9 eggs) and initiate incubation before completing them (approximately with egg 3), but the young hatch and leave the nest synchronously. Both conductance (from ∼15 mg H2O torr-1 day-1 for the first to ∼25 mg H2O torr-1 day-1 for the eighth egg in the clutch) and porosity (from ∼2.5 pores cm 2 for the first to ∼3.0 pores cm -2 for the eighth egg in the clutch) increased...

[学科分类] 动物科学

[关键词] Branta canadensis;Canada Goose;conductance;porosity;position in the sequence of laying