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Saint-Sauveur-en-Rue, France

Zimmer C.,CNRS Hubert Curien Multi-disciplinary Institute | Boos M.,Research Agency in Applied Ecology | Petit O.,CNRS Hubert Curien Multi-disciplinary Institute | Robin J.-P.,CNRS Hubert Curien Multi-disciplinary Institute
Journal of Avian Biology | Year: 2010

For passerines the starvation-predation risk theory predicts that birds should decrease their body mass to improve escape flight performance, when predation pressure increases. To investigate whether this theory may apply to large birds, which manage body reserves differently from small passerines, we experimentally increased the predation risk in mallards Anas platyrhynchos. Two groups were disturbed at different frequencies during experimental sessions lasting one week, while a control group was left undisturbed. We found that body mass loss and final wing loading were similar in both disturbed groups and significantly differed from the control group. Food intake in disturbed groups was reduced up to day four of the disturbance session and was lower than in the control group. Altogether our results suggest that disturbed mallards may adjust their body mass to reach a more favorable wing loading, supposedly to improve escape flight performance. Nevertheless, body mass loss in our mallards was double than what has been observed in passerines. This greater mass decrease might be explained by different strategies concerning energy storage. Furthermore, in large birds the predation component of the starvation-predation trade-off might be of greater importance. Hence, the observed relevance of this trade-off over a large size range suggests that the starvation-predation risk theory is of major ecological significance for many animal species. © 2010 The Authors. Source

Ramo C.,CSIC - Donana Biological Station | Amat J.A.,CSIC - Donana Biological Station | Nilsson L.,Lund University | Schricke V.,Office National de la Chasse et de la Faune Sauvage | And 8 more authors.
PLoS ONE | Year: 2015

The unusually high quality of census data for large waterbirds in Europe facilitates the study of how population change varies across a broad geographical range and relates to global change. The wintering population of the greylag goose Anser anser in the Atlantic flyway spanning between Sweden and Spain has increased from 120 000 to 610 000 individuals over the past three decades, and expanded its wintering range northwards. Although population sizes recorded in January have increased in all seven countries in the wintering range, we found a pronounced northwards latitudinal effect in which the rate of increase is higher at greater latitudes, causing a constant shift in the centre of gravity for the spatial distribution of wintering geese. Local winter temperatures have a strong influence on goose numbers but in a manner that is also dependent on latitude, with the partial effect of temperature (while controlling for the increasing population trend between years) being negative at the south end and positive at the north end of the flyway. Contrary to assumptions in the literature, the expansion of crops exploited by greylag geese has made little contribution to the increases in population size. Only in one case (expansion of winter cereals in Denmark) did we find evidence of an effect of changing land use. The expanding and shifting greylag population is likely to have increasing impacts on habitats in northern Europe during the course of this century. © Copyright: 2015 Ramo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Pellegrino I.,University of Piemonte Orientale | Cucco M.,University of Piemonte Orientale | Follestad A.,Norwegian Institute for Water Research | Boos M.,Research Agency in Applied Ecology
PeerJ | Year: 2015

Greylag goose populations are steadily increasing in north-western Europe. Although individuals breeding in the Netherlands have been considered mainly sedentary birds, those fromScandinavia or northern Germany fly towards their winter quarters, namely over France as far as Spain. This study aimed to determine the genetic structure of these birds, and to evaluate how goose populations mix. We used mitochondrial DNA and microsatellites from individuals distributed throughout the European Atlantic flyway, from breeding sites in Norway and the Netherlands to stopover and wintering sites in northern and south-western France. The mtDNA marker (CR1 D-Loop, 288 bp sequence, 144 ind.) showed 23 different haplotypes. The genetic distances amongst individuals sampled in Norway, northern France and the Netherlands were low (range 0.012-0.013). Individuals in south-western France showed a slightly higher genetic distance compared to all other sampling areas (ranges 0.018-0.022). The NJ tree does not show evidence of any single clades grouping together all individuals fromthe same geographic area. Besides, individuals from each site are found in different branches. Bayesian clustering procedures on 14 microsatellites (169 individuals) did not detect any geographically distinct cluster, and a high genetic admixture was recorded in all studied areas except for the individuals from the breeding sites in Norway, which were genetically very close. Estimation of migration rates through Bayesian inference confirms the scenario for the current mixing of goose populations. © 2015 Pellegrino et al. Source

Boos M.,Research Agency in Applied Ecology | Boos M.,CNRS Hubert Curien Multi-disciplinary Institute | Auroy F.,Research Agency in Applied Ecology | Zimmer C.,CNRS Hubert Curien Multi-disciplinary Institute | And 4 more authors.
Wildlife Biology in Practice | Year: 2010

The debate concerning the relative importance of the costs and benefits of parental investment decisions has created considerable controversy. This is especially true in the discussion for duck species, where the link between ending of parental care and offspring survival has not been fully determined. This experimental study tests whether mallard ducklings (Anas platyrhynchos; a non-crèching species with maternal care-) achieve maximum survival potential before the typical ending of the hen-brood bond. As mortality rates are at their highest during the first two weeks post-hatching, our experimental investigation of survival was restricted to ducklings from 2 weeks of age until fledging, in non-deserted (ND, control group; n=36) and prematurely abandoned (D, deserted treatment group; n=35) broods under free-ranging conditions. The experiment was conducted over two years to take differences in weather conditions into account. According to age periods, survival rates ranged from 65 to 95% in the D group and from 97 to 100% in the ND. Survival probability of deserted ducklings was 23% lower than that of the control group (p < 0.001) in 15 to 30 day old ducklings but was similar (p > 0.09) thereafter. Assuming that the hen-brood bond is time-disrupted at ~6 weeks post-hatching, our results are consistent with the idea that trade-offs associated with the provision and the consequent ceasing of maternal care have evolved according to the intrinsic ability of ducklings to survive on their own at ~4 weeks post-hatching. The dissipation of the behavioural-hormonal processes underlying the hen-brood bond probably requires a delay between these two events. The maintaining of maternal care for ~4 weeks post-hatching also coincides with the most critical periods of duckling vulnerability after hatching, during which the hen has an important anti-predator role to play. Source

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