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Stratégies individuelles d'hivernage chez la bécasse des bois (Scolopax rusticola) : compromis énergétiques pour la sélection de l'habitat

Abstract : The Eurasian Woodcock (Scolopax rusticola L.) is a migratory bird species with an uncertain conservation status, whose ecology and behaviour are mostly unknown in winter. Woodcocks are known to be sensitive to frost, and are threatened by habitat loss and high hunting pressures in winter, which is a period of enhanced vulnerability due to the concentration of populations. This study aims to understand the behavioural strategies in winter by combining eco-physiology and behavioural ecology approaches, to propose accurate management and conservation measures. Birds must resolve a trade-off between feeding and predator avoidance according to their energetic requirements. The trade-off could thereby impact on habitat selection. Studies of energetic expenditures in laboratory (basal metabolic rate and thermoregulation) and in the field revealed that woodcocks were well insulated and had a rather low energy expenditure compared to other wader species. Woodcocks live in two types of habitat in winter: wooded habitats during the day (woodland and hedges) and agricultural habitats at night. Habitat selection, spatial use, survival and time-budget have been studied during three winters in Brittany, using about a hundred woodcocks fitted with radio-transmitters. Diurnal habitats were selected according to their richness in earthworms (their main food item) and in shrub cover (for protection). At night, grazed meadows were preferred to crops for their richness in earthworms. Natural mortality by predation occurred mostly in the fields at night and survival rates suggested an additive mortality due to hunting. The trade-off between starvation and predation risk lead individuals to adopt different behavioural strategies of space use and time-budget management. Some individuals only used one site while others visited several sites, alternatively or successively. The choice of strategy seems to depend on the efficiency of individuals to forage and escape predators. The use of meadows at night, which varies among individuals, gives another explanation to the starvation / predation trade-off. Depending on their energetic needs (function of air temperature) and their own foraging efficiency, individuals that increased their foraging effort during the day, could decide to stay in the forest at night in order to minimise predation risks. These results are discussed in scientific and conservation perspectives. Solutions of habitat management are proposed for a sustainable use of woodcock populations.
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Contributor : Olivier Duriez <>
Submitted on : Wednesday, October 22, 2003 - 11:43:27 AM
Last modification on : Friday, May 29, 2020 - 4:02:16 PM
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  • HAL Id : tel-00003509, version 1

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Olivier Duriez. Stratégies individuelles d'hivernage chez la bécasse des bois (Scolopax rusticola) : compromis énergétiques pour la sélection de l'habitat. Ecologie, Environnement. Université Pierre et Marie Curie - Paris VI, 2003. Français. ⟨tel-00003509⟩

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