Individual activity rates in wintering Eurasian woodcocks: starvation versus predation risk trade-off?

doi:10.1016/j.anbehav.2004.04.009

Animal Behaviour

Volume 69, Issue 1, January 2005, Pages 39-49

https://doi.org/10.1016/j.anbehav.2004.04.009 Get rights and content

Wintering birds face a trade-off between starvation and predation risk. In Eurasian woodcocks, Scolopax rusticola, habitat use may reflect this trade-off because meadows, where most birds spend the night, are characterized by a higher risk of predation and a higher biomass of food (earthworms) than the woods, used by day. We monitored activity of 34 woodcocks fitted with tiltswitch radiotags. Young birds were more active than adults, probably because they were less efficient at foraging. In general, nocturnal activity was inversely correlated with air temperature and with daylight foraging activity, suggesting some compensatory mechanism, modulated by thermoregulatory constraints. Individual activity patterns differed, and we classified woodcocks according to three main wintering strategies: ‘always’, ‘sometimes’ or ‘never’ visiting fields at night. The decision to fly to fields at night seemed to be taken every evening, according to the amount of daylight foraging activity in woods and the air temperature. After feeding in a rich patch of food on a mild day, woodcocks did not have to risk going to meadows. Conversely, in patches of fewer food resources or at lower temperatures or both, woodcocks could not meet all their energy requirements without going to fields at night (where there was always sufficient food) and eventually, changing their diurnal sites. Therefore, the trade-off between feeding and predation risk depends on how efficiently birds find a rich patch of food in the forest and exploit it optimally during the day.

Section snippets

Study area

We collected data during December to April in two winters (2000–2001 and 2001–2002, hereafter called 2001 and 2002 winters, respectively). The study area (ca. 1800 ha) was in Brittany, western France (48°30′N, 3°28′W), and comprised the Beffou forest and the surrounding bocage. The bocage is a typical landscape in western France, with small fields separated by old woody hedges. The topography was composed of small hills (range of altitude 160–322 m) and valleys. Woodcock hunting has been

Activity patterns

Birds were assigned to four behavioural strategies: two birds never commuted from forest to fields at night (strategy Never), 13 sometimes commuted (strategy Sometimes), 15 always commuted (strategy Always) and three birds always used hedges (Hedge). One other individual had no assigned strategy because it was shot early in the season. We first describe the patterns of activity for all birds and then compare the three strategies of birds that stayed in woodlands by day (birds that stayed in

Winter activity rates

Our results are the first to show evidence for diurnal foraging by woodcocks under nonfreezing weather conditions in winter, whereas diurnal foraging seems to be the rule during summer (Cramp and Simmons, 1983, Ferrand and Gossmann, 1995). Individuals that stayed in the woods at night (WW) fed mainly during the day. Even birds that went to fields at night (WF) fed for an appreciable part of the day. The total feeding durations reported here seem rather low (about 5 h out of 24) but a similar

Acknowledgments

This study was funded by the Office National de la Chasse et de la Faune Sauvage. We are very grateful to all the persons involved in the fieldwork: Yannick Chaval, Jean-Luc Chil, Sébastien Descamps, Cédric Guyot, François Gossmann, Hervé Jamin, Julie Le Bihan, Frédérique Leroy, Jérôme Marie, Jean-Pierre Richard and Sophie Alary. Many thanks to Gwenaële Eon and Valérie Farcy for the determination of 41 000 earthworms! François Brichoux drew Fig. 1. We are grateful for the logistic facilities

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¹: H. Fritz and Y. Tremblay are at CNRS – Centre d'Etudes Biologiques de Chizé, UPR 1934, 79360 Beauvoir-sur-Niort, France.

²: F. Binet is at CNRS, UMR 6553 Ecobio, 263 avenue du Général Leclerc, Campus de Beaulieu Universite´ de Rennes I, Bât 14B, CS74205, 35042 Rennes Cedex, France.

³: Y. Ferrand is at the Office National de la Chasse et de la Faune sauvage, CNERA Avifaune Migratrice, 5 rue de St-Thibaut, BP 20 St-Benoist, 78612 Le-Perray-en-Yuelines, Cedex, France.

View full text

Individual activity rates in wintering Eurasian woodcocks: starvation versus predation risk trade-off?

Section snippets

Study area

Activity patterns

Winter activity rates

Acknowledgments

Animal Behaviour

Theoretical Population Biology

Pedobiologia

Animal Behaviour

Soil Biology and Biochemistry

Soil Biology and Biochemistry

Compositional analysis of habitat use from animal radio-tracking data

Ecology

Estimating the effect of wind on avian metabolic rate with standard operative temperature

Auk

Great tit fat reserves under unpredictable temperatures

Journal of Avian Biology

Effect of bird predation on lumbricid populations

Oikos

Contre une dégradation physique et chimique des sols et pour leur optimisation économique, l'échantillonnage des lombriciens: une urgente nécessité

La Défense des Végétaux

An aerodynamic basis for selecting transmitters loads in birds

Wilson Bulletin

Age and sex determination of the woodcock (Scolopax rusticola)

Danish Review of Game Biology

Scolopax rusticola woodcock

Managing time and energy

Body mass regulation in response to changes in feeding predictability and overnight energy expenditure

Behavioral Ecology

Low levels of energy expenditures in a nocturnal, forest-dwelling wader, the Eurasian woodcock Scolopax rusticola

Ardea

Monitoring starvation risk: adjustments of body reserves in greenfinches (Carduelis chloris L.) during periods of unpredictable foraging success

Behavioral Ecology

Monitoring activity patterns using a micro-computer-controlled radiotelemetry system, tested for waders (Charadrii) as an example

La Bécasse des Bois

La Bécasse des Bois

Depletion models can predict shorebird distribution at different spatial scales

Proceedings of the Royal Society of London, Series B

Where to feed