Thesis for a trade-off with breeding success

Tamisier, Alain and Dehorter, Olivier (1997) Thesis for a trade-off with breeding success. MAGYAR VÍZIVAD KÖZLEMÉNYEK, 3. pp. 185-186. ISSN 1416-1389

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Abstract

According to the most recent studies, breeding success in several waterfowl species (geese, ducks, coots, shorebirds) has been correlated with nutrient reserves (mostly lipids, but also proteins) stored at the end of the winter season whilst birds are still on their winter quarters. Wintering strategies suggest that body condition of birds at the end of the winter season is controlled by body condition at the beginning of the winter season. Wintering strategies analysed on several duck species in Camargue, south France on the mediterranean shore, allow birds to optimize daily allocation of time and energy. Considered as a model to be realised at the individual level, they rely on ecological links between three successive periods. 1) Restoring period. When birds arrive at tne winter quarter, they must refuel after migrationtill optimum weights are reached. Daily feeding times are long and the period lasts 2-3 months. 2)Pairing period. Birds have enough stored energy to reduce daily feeding and sleepingduration. This is the only period in the winter season wnen they have some extra time and theytake advantage it for courtship and pairing. 3) Fattening period. From January onwards,environmental conditions become worst, food is scarce and birds must store energy for springmigration and breeding. During this period, daily feeding durations are the longest and a strongmtraspecific competition for food occurs where paired birds are hierarchically dominant...

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