Choinière Line, Gauthier Gilles
Département de biologie & Centre d'Études Nordiques, Université Laval, G1K 7P4, Ste-Foy, Qc, Canada.
Oecologia. 1995 Aug;103(3):379-389. doi: 10.1007/BF00328628.
Arctic-nesting geese are classified as "capital" breeders (i.e., birds that rely largely on endogenous reserves to meet the high nutrient requirement of clutch formation) as opposed to "income" breeders (those that rely directly on ingested food). However, some evidence has suggested that energy reserves of greater snow geese (Chen caerulescens atlantica) are not sufficient to meet these costs. We tested whether greater snow geese were capital breeders and examined the consequences on their reproductive strategy. We collected 48 females and 47 males from arrival at the breeding colony on Bylot Island (NWT) to the postlaying stage, and determined fat and protein content in somatic and reproductive tissues. Rapid follicular growth was initiated only after arrival on the breeding ground. Somatic fat of females tended to increase during the prelaying and laying stages at the same time that most of the fat was deposited in developing follicles. Decrease in somatic fat in postlaying females was mostly related to its use for meeting metabolic requirements during early incubation. Hence, almost all fat invested in the clutch came from food intake, not endogenous reserves. Somatic protein was maintained during prelaying but decreased during laying, suggesting that some protein reserves were deposited in the eggs. There was no relationship between somatic fat and the number of developing follicles (incubating females excluded) but a relationship was found with somatic protein. Clutch size was not related to body size. In males, somatic fat, which was similar to females at arrival, was almost completely depleted by the postlaying stage. Male somatic protein remained stable. Male somatic reserves were not related to the somatic reserves, clutch size or nutrient investment in reproduction of their mate. We conclude that, in female greater snow geese, little fat reserves (if any) were used for egg formation though some protein reserves were used, whereas males relied heavily on their fat reserves during the same period. This is probably a consequence of the long and costly migration between the last staging area and the breeding grounds.
在北极筑巢的鹅被归类为“资本型”繁殖者（即主要依靠内源性储备来满足形成一窝蛋所需的高营养需求的鸟类），与之相对的是“收入型”繁殖者（即直接依靠摄取食物的鸟类）。然而，一些证据表明，大雪雁（雪雁指名亚种）的能量储备不足以满足这些成本。我们测试了大雪雁是否为资本型繁殖者，并研究了其对繁殖策略的影响。我们从它们抵达位于努纳武特地区拜洛特岛的繁殖地，一直到产蛋后期，收集了48只雌性和47只雄性大雪雁，并测定了其躯体组织和生殖组织中的脂肪和蛋白质含量。卵泡快速生长仅在抵达繁殖地后才开始。雌性的躯体脂肪在产蛋前和产蛋阶段往往会增加，与此同时，大部分脂肪沉积在发育中的卵泡中。产蛋后雌性躯体脂肪的减少主要与其在早期孵化期间用于满足代谢需求有关。因此，几乎所有投入到一窝蛋中的脂肪都来自食物摄入，而非内源性储备。躯体蛋白质在产蛋前保持不变，但在产蛋期间减少，这表明一些蛋白质储备被沉积到了蛋中。躯体脂肪与发育中的卵泡数量（不包括正在孵化的雌性）之间没有关系，但与躯体蛋白质存在关系。窝卵数与体型大小无关。在雄性中，抵达时与雌性相似的躯体脂肪在产蛋后期几乎完全耗尽。雄性躯体蛋白质保持稳定。雄性的躯体储备与配偶的躯体储备、窝卵数或繁殖中的营养投入均无关。我们得出结论，在雌性大雪雁中，几乎没有脂肪储备（如果有的话）用于形成蛋，不过一些蛋白质储备被利用了，而在同一时期雄性则严重依赖其脂肪储备。这可能是由于从最后一个停歇地到繁殖地之间漫长且代价高昂的迁徙所致。
