Les Marais du Vigueirat

Chaillé-les-Marais, France

Les Marais du Vigueirat

Chaillé-les-Marais, France
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Champagnon J.,Office National de la Chasse et de la Faune Sauvage | Champagnon J.,CNRS Center of Evolutionary and Functional Ecology | Crochet P.-A.,CNRS Center of Evolutionary and Functional Ecology | Kreisinger J.,Charles University | And 8 more authors.
Animal Conservation | Year: 2013

Captive-bred mallards Anas platyrhynchos have been released for hunting purposes at a very large scale in Europe since the mid-1970s. In spite of a potential genetic impact, the actual contribution of restocked mallards to the genome of the target population has received little attention. The genetic structure of modern wild mallards in the Camargue, Southern France, was assessed from two samples: one originating from shot birds in hunting bags and one from presumed wild ducks captured alive in a hunting-free reserve. Reference samples originated from five mallard farms, as well as from museum samples collected before the mid-1970s (i.e. before massive mallard releases started). Our results revealed that the genetic signature of wild wintering mallards has not changed significantly because museum and presumed wild samples from the Camargue hunting-free nature reserve were genetically similar, and clearly differentiated from the farm mallards. This suggests that mallard releases in the Camargue or elsewhere in France, although massive, have not actually translated into complete admixture of wild and captive genomes, most likely due to low survival of released birds once in the wild. Nevertheless, although genetic introgression of the wild population by captive-bred was contained, we found significant rates of hybridization between wild and captive-bred mallards in modern samples. This result suggests that long-term releases of captive-bred mallards, if carried on at such large scale, could compromise irreversibly the genetic structure and composition of European mallards. This work contributes to fill in the gap on the monitoring of the genetic consequences of large-scale game releases for exploitation. © 2012 The Zoological Society of London.

Caizergues A.,Office National de la Chasse et de la Faune Sauvage | Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Arzel C.,Office National de la Chasse et de la Faune Sauvage | Arzel C.,Kristianstad University College | And 6 more authors.
Wildlife Biology | Year: 2011

During the winter of 2003/04, we studied emigration rates of teal Anas crecca in two major wetlands: the Camargue (southern France) and the Loire estuary (western France). We derived local survival probabilities as a step in ultimately estimating emigration rates from individual mark-resighting (visual recaptures) history of birds fitted with nasal saddles. In goodness-of-fit tests of time-dependent models for local survival, we only detected the presence of transients among young females in the Loire estuary, which indicated that this category of individuals includes an 'unstable compartment' continuing its migratory journey further to the south. We observed low monthly local survival and high emigration rates (range: 0.01-0.81) in both areas, which suggests high turnover rates. In the Loire estuary, temporal changes in emigration rates matched the post- and pre-nuptial migration peaks (i.e. October-November and February-March). By combining local survival probabilities and count data, we derived an estimate of the ratio between the winter peak count of teals in our study areas and the minimum number of birds that actually frequented the areas over the entire wintering period (October-March). In both cases, we estimated the number of teal visiting the two wintering sites be about twice as large as the maximum number of birds counted instantaneously. © Wildlife Biology, NKV.

Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Gourlay-Larour M.-L.,Office National de la Chasse et de la Faune Sauvage | Gourlay-Larour M.-L.,National School of Engineering in Agricultural and Food Industries | Cavallo F.,Office National de la Chasse et de la Faune Sauvage | And 7 more authors.
Ibis | Year: 2015

Concerns about the spread of avian influenza viruses (AIVs) have led to cloacal swab sampling of hundreds of thousands of birds worldwide as part of AIV surveillance schemes, but the effects of cloacal swabbing have not been adequately evaluated. We tested for differences between swabbed, swabbed and bled, and non-sampled wild ducks in terms of live re-encounter and dead recoveries for Common Pochard Aythya ferina and Tufted Duck Aythya fuligula, and also determined re-encounter and recovery rates for Mallard Anas platyrhynchos and Common Teal Anas crecca. No effects of sampling methods were detected, except in Teal. Re-encounter rates were lower in sampled Teal than in controls, with annual re-encounter probabilities being 25% and 35% lower in males and females, respectively. Teal possibly left or avoided sampling sites, or sought sites where they were less detectable after sampling. In general, no deleterious effects were found, suggesting that cloacal swabbing and blood sampling are suitable methods for conducting AIV surveillance in ducks. © 2015 British Ornithologists' Union.

Champagnon J.,Office National de la Faune Sauvage | Champagnon J.,CNRS Center of Evolutionary and Functional Ecology | Guillemain M.,Office National de la Faune Sauvage | Elmberg J.,Kristianstad University College | And 2 more authors.
European Journal of Wildlife Research | Year: 2012

Captive-reared animals used in reinforcement programs are generally less likely to survive than wild conspecifics. Digestion efficiency and naive behaviour are two likely reasons for this pattern. The Mallard is a species with high adaptability to its environment and in which massive reinforcement programs are carried out. We studied physiological and behavioural factors potentially affecting body condition and survival of captive-reared Mallards after being released. Digestive system morphology and an index of body condition were compared among three groups: captive-reared birds remaining in a farm (control), captive-reared birds released into the wild as juveniles (released) and wild-born birds (wild). We also compared behaviour and diet of released vs. wild Mallards. Finally, we conducted a 1-year survival analysis of captive-reared birds after release in a hunting-free area. Gizzard weight was lower in control Mallards, but the size of other organs did not differ between controls and wild birds. The difference in gizzard weight between released and wild birds disappeared after some time in the wild. Diet analyses suggest that released Mallards show a greater preference than wild for anthropogenic food (waste grain, bait). Despite similar time-budgets, released Mallards never attained the body condition of wild birds. As a consequence, survival probability in released Mallards was low, especially when food provisioning was stopped and during harsh winter periods. We argue that the low survival of released Mallards likely has a physiological rather than a behavioural (foraging) origin. In any case, extremely few released birds live long enough to potentially enter the breeding population, even without hunting. In the context of massive releases presently carried out for hunting purposes, our study indicates a low likelihood for genetic introgression by captive-reared birds into the wild population. © 2011 Springer-Verlag.

Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Elmberg J.,Kristianstad University College | Massez G.,Les Marais du Vigueirat | Hearn R.,Wildfowl and Wetlands Trust | And 2 more authors.
Ambio | Year: 2010

Animal populations are exposed to large-scale anthropogenic impact from e.g. climate change, habitat alteration and supplemental stocking. All of these may affect body condition in wintering dabbling ducks, which in turn may affect an individual's survival and reproductive success. The aim of this study was to assess whether there have been morphometric changes in Mallard (Anas platyrhynchos) and Teal (Anas crecca) over the last 30 years at a major wintering site. Body mass and condition increased from the 1950s1960s to the 2000s in both species. The increase in body mass amounted to as much as 11.7%, with no corresponding change in body size. Improved body condition was maintained from early to mid-winter, but then converged with historical values for late winter. Our interpretation is that increasingly benign ambient winter conditions permit ducks to maintain better energetic "safety margins" throughout winter, and that converging spring departure values may be related to evolutionary flight energetic optima. The observed changes are consistent with large-scale climate amelioration and local/regional habitat improvement (both anthropogenic). © 2010 Royal Swedish Academy of Sciences.

Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Cavallo F.,Office National de la Chasse et de la Faune Sauvage | Massez G.,Les Marais du Vigueirat | George T.,Office National de la Chasse et de la Faune Sauvage | And 8 more authors.
Wildfowl | Year: 2015

Studies of waterbirds rely to a large extent on ringing and resighting or recapture data, whilst assuming that ringed birds are broadly representative of the population as a whole. This may not be the case if the capture process may in itself have an influence on the birds. The analyses presented here showed that the body mass of ringed ducks often decreases between capture and recapture if the latter occurs within a few days or weeks. This could possibly reflect stress caused by handling, which would be problematic if it causes ringed birds to behave in a way that differs from the population as a whole. Alternatively, body mass measurements could also be biased by the general use of bait to attract birds to the trap. Initial and subsequent body mass data recorded for Eurasian Teal Anas crecca caught then recaptured within three weeks were compared between sites where the birds were attracted to traps with bait or with live decoys. When bait was used individuals had a greater body mass at ringing but were lighter at recapture at all but one site, where only a marginal difference was found. Conversely, when using live decoys, body mass remained constant at the next capture event. This suggests that mass loss commonly observed between capture and recapture is not caused by handling, but is potentially an artefact linked to duck hyperphagia in the presence of abundant food at ringing. It also implies that most available duck body mass data, which are usually obtained from birds ringed at baited traps, may be artificially inflated. The present results are based on one single unbaited site, however, and experimental manipulative studies (alternating the use of bait and live decoys to trap birds) are needed to confirm the findings. ©2015 Wildfowl & Wetlands Trust.

Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Massez G.,Les Marais du Vigueirat | Pernollet C.A.,Office National de la Chasse et de la Faune Sauvage | George T.,Office National de la Chasse et de la Faune Sauvage | Momerency A.,Impression Nature Environnement
Wildfowl | Year: 2015

Earlier studies from central and northern Europe have found a shortening of the ring recovery distance in Mallard Anas platyrhynchos, which was generally attributed to climate change leading to a northwards shift of the wintering range. Here we show that recovery distances for Mallard ringed during winter in the Camargue (southern France), at the southern end of their range, have also shortened over the last 50 years, from a mean of 417 km (s.e. ± 17.4) for birds ringed between 1950-1978 to 74 km (± 28.9) for birds ringed between 2002-2013. In contrast to the studies in other areas, however, the more recent recoveries of Mallard ringed in the Camargue were made to the south and west of where they were previously, and changes in ring recoveries were likely caused by a greater proportion of sedentary birds among the Camargue wintering population. Discarding unlikely methodological biases that may explain the pattern observed, we suggest three non-mutually exclusive hypotheses to explain such a change: A) increased attractiveness of Camargue habitats as a winter quarter, with migrant birds now staying for longer periods and allowing more local recoveries, b) hybridization between resident captive-bred and wild Mallards, and c) former migrants from northern Europe now foregoing long migration to this distant winter quarter due to climate change. Future studies combining genetic and isotope analyses may help in teasing these hypotheses apart, to provide a better understanding of the factors leading to such increased sedentarity. ©2015 Wildfowl & Wetlands Trust.

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