La Tour du Valat

Azay-le-Rideau, France

La Tour du Valat

Azay-le-Rideau, France
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Gayet G.,9 rue du 4 septembre | Eraud C.,Office National de la Chasse et de la Faune Sauvage | Benmergui M.,Office National de la Chasse et de la Faune Sauvage | Broyer J.,Office National de la Chasse et de la Faune Sauvage | And 4 more authors.
European Journal of Wildlife Research | Year: 2011

A number of native and exotic animal species show dramatic population increases in terms of both numbers and geographic range. Understanding the habitat selection processes behind such increases is crucial to implement adequate management measures. Mute swan (Cygnus olor) populations have experienced a tremendous demographic and geographic expansion in Western Europe during the twentieth century, colonizing a wide variety of aquatic habitats. We aimed at assessing how swans select nesting sites during the pre-laying and laying periods on medium to large fishponds (from 10 to 50 ha) in Eastern France, while accounting for detectability biases and testing for the effects of fishpond spatial configuration, vegetation resources, human disturbance and habitat management. Our results demonstrate that the mute swan is a non-selective species regarding its nesting habitat among such fishponds, using these independently from the parameters considered although fishpond characteristics varied. Although mute swan is one of the least cryptic Anatidae, owing to its white colour and large size, detection of breeding pairs remained imperfect for each over several sampling occasions. However, because we repeated the sampling sessions, detection of swan pairs by the end of the monitoring period was as high as 0. 94. These results are consistent with previous assertions that the mute swan is a species of high ecological plasticity, which may partly explain its recent colonization rates. Given that even swan breeding events were imperfectly detected on each occasion, we highlight the fact that most studies of breeding ducks (which are more cryptic) would be considerably improved by better considering detection biases. © 2011 Springer-Verlag.

Maris V.,French Natural History Museum | Maris V.,CNRS Center of Evolutionary and Functional Ecology | Bechet A.,La Tour du Valat
Conservation Biology | Year: 2010

The conservation of biodiversity poses an exceptionally difficult problem in that it needs to be effective in a context of double uncertainty: scientific (i.e., how to conserve biodiversity) and normative (i.e., which biodiversity to conserve and why). Although adaptive management offers a promising approach to overcome scientific uncertainty, normative uncertainty is seldom tackled by conservation science. We expanded on the approach proposed by adaptive-management theorists by devising an integrative and iterative approach to conservation that encompasses both types of uncertainty. Inspired by environmental pragmatism, we suggest that moral values at stake in biodiversity conservation are plastic and that a plurality of individual normative positions can coexist and evolve. Moral values should thus be explored through an experimental process as additional parameters to be incorporated in the traditional adaptive-management approach. As such, moral values should also be monitored by environmental ethicists working side by side with scientists and managers on conservation projects. Acknowledging the diversity of moral values and integrating them in a process of collective deliberation will help overcome the normative uncertainty. We used Dewey's distinction between adaptation and adjustment to offer a new paradigm built around what we call adjustive management, which reflects both the uncertainty and the likely evolution of the moral values humans attribute to biodiversity. We illustrate how this paradigm relates to practical conservation decisions by exploring the case of the Sacred Ibis (Threskiornis aethiopicus. ), an alien species in France that is the target of an eradication plan undertaken with little regard for moral issues. We propose that a more satisfying result of efforts to control Sacred Ibis could have been reached by rerouting the traditional feedback loop of adaptive management to include a normative inquiry. This adjustive management approach now needs to be tested in real-case conservation programs. ©2010 Society for Conservation Biology.

An J.,Seoul National University | Bechet A.,La Tour du Valat | Berggren A.,Swedish University of Agricultural Sciences | Brown S.K.,University of California at Davis | And 108 more authors.
Molecular Ecology Resources | Year: 2010

This article documents the addition of 411 microsatellite marker loci and 15 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Acanthopagrus schlegeli, Anopheles lesteri, Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus oryzae, Aspergillus terreus, Branchiostoma japonicum, Branchiostoma belcheri, Colias behrii, Coryphopterus personatus, Cynogolssus semilaevis, Cynoglossus semilaevis, Dendrobium officinale, Dendrobium officinale, Dysoxylum malabaricum, Metrioptera roeselii, Myrmeciza exsul, Ochotona thibetana, Neosartorya fischeri, Nothofagus pumilio, Onychodactylus fischeri, Phoenicopterus roseus, Salvia officinalis L., Scylla paramamosain, Silene latifo, Sula sula, and Vulpes vulpes. These loci were cross-tested on the following species: Aspergillus giganteus, Colias pelidne, Colias interior, Colias meadii, Colias eurytheme, Coryphopterus lipernes, Coryphopterus glaucofrenum, Coryphopterus eidolon, Gnatholepis thompsoni, Elacatinus evelynae, Dendrobium loddigesii Dendrobium devonianum, Dysoxylum binectariferum, Nothofagus antarctica, Nothofagus dombeyii, Nothofagus nervosa, Nothofagus obliqua, Sula nebouxii, and Sula variegata. This article also documents the addition of 39 sequencing primer pairs and 15 allele specific primers or probes for Paralithodes camtschaticus. © 2010 Blackwell Publishing Ltd.

Gayet G.,9 rue du 4 septembre | Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Mesleard F.,La Tour du Valat | Mesleard F.,University of Avignon | And 3 more authors.
Journal of Ornithology | Year: 2011

The Mute Swan (Cygnus olor) is a protected species whose population has shown a dramatic demographic expansion over the last decades in France. Today, Mute Swans are suspected of causing damages to wetlands, partly through their territorial behaviour towards other waterbirds. The behaviour of Mute Swan pairs and the distribution of other waterbirds was monitored over 84 fishponds in the Dombes, Eastern France, from April to July 2008. Interspecific aggressive behaviours by Mute Swan pairs were not detected during behavioural observations, and no negative impact of swan pair presence was demonstrated on waterbird distribution. Waterbirds were more abundant on fishponds where Mute Swan pairs were present, maybe due to the flocking of waterbirds where Mute Swans were established owing to shared habitat preferences. Indeed, the waterbirds whose presence was the most closely correlated to that of Mute Swan pairs were Coot (Fulica atra), Common Pochard (Aythya ferina) and Red-Crested Pochard (Netta rufina), all foraging on deep macrophyte beds as do the swans. All these species, including swans, may therefore be attracted to the same fishponds without massive interspecific competition occurring, due to abundant submerged aquatic vegetation resources. © 2010 Dt. Ornithologen-Gesellschaft e.V.

Gayet G.,9 rue du 4 septembre | Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Benmergui M.,Office National de la Chasse et de la Faune Sauvage | Mesleard F.,La Tour du Valat | And 5 more authors.
Oikos | Year: 2011

Foragers in patchy environments do not only select sites for single patch characteristics, but also have to consider the local environment of such patches. We studied habitat selection by mute swans Cygnus olor in a wide and heterogeneous fishpond region (the Dombes, eastern France). In this study, we considered fishpond isolation, resource quality within fishponds and breeding status of mute swans during both summer and winter. Mute swans did not select aquatic habitat randomly within the landscape. During summer, the population spread preferentially on medium to large fishponds, in subregions with numerous or closely related waterbodies, without generating a clumped distribution of birds. In addition to a positive effect of local fishpond number (2 km radius), breeding birds also responded positively to fishpond size. Non-breeders selected fishponds mainly according to their size. Intraspecific territoriality did not appear to limit the presence of non-breeders (i.e. moulting flocks), since both breeders and non-breeders could coexist on the larger fishponds. During winter, mute swans used medium to large reflooded fishponds after summer drainage. The surrounding aquatic environment of fishponds played a minor role in determining flocking, compared to actual patch quality. Flocking occurred on large fishponds that had reflooded after having dried the summer before, whatever the agricultural cultivation practiced in the summer following drainage. The results suggest that geographical aspects should be taken into account when considering the potential impact of this expanding species within such ecosystems, and also in more general management policies dealing with aquatic habitats for waterbird populations. © 2011 The Authors.

Gayet G.,9 rue du 4 septembre | Guillemain M.,Office National de la Chasse et de la Faune Sauvage | Fritz H.,CNRS Biometry and Evolutionary Biology Laboratory | Mesleard F.,La Tour du Valat | And 6 more authors.
Aquatic Botany | Year: 2011

The mute swan (Cygnus olor Gmelin) is one of the largest herbivorous waterbirds in the world. Its population increased dramatically over the last decades in Western Europe, leading to concerns about its potential impact on aquatic ecosystems. Indeed, swan consequences on fishponds remain poorly investigated, although fishpond animal communities and economic value both largely depend on aquatic macrophytes. We carried out an experiment in the Dombes region (Eastern France) with 96 exclosures on 24 fishponds. Our aim was to assess the impact of swan grazing on aquatic macrophyte presence, abundance and community structure (diversity and evenness) during the growing season (April to July). We also considered the potential effect of swan stay (i.e. number of swan days ha-1) and nutrient availability on macrophyte depletion. Swan grazing negatively affected the presence and abundance (% cover) of macrophyte beds, particularly at high swan density. No significant effect on dry biomass was found. Furthermore, swan grazing negatively affected community structure, suggesting that mute swan promoted the dominance of a few species in macrophyte communities. Whatever the macrophyte variable considered, nutrient availability in fishponds did not affect macrophyte depletion rate. It is speculated that both the repeated use of the same fishponds by birds and their expansion within the landscape may lead to more acute and broader consequences for macrophyte beds over the longer term. © 2011 Elsevier B.V.

Gayet G.,La Tour du Valat | Croce N.,France Inter | Grillas P.,La Tour du Valat | Nourry C.,France Inter | And 2 more authors.
Aquatic Botany | Year: 2012

The mute swan Cygnus olor Gmelin and the greater flamingo Phoenicopterus roseus Pallas potentially affect plants, directly through grazing and indirectly through mechanical disturbance during their foraging activities. We studied in a field exclosure experiment, from May 2010 to July 2011, their respective impact on macrophytes in two Mediterranean lagoons (Camargue, South of France) with different plant communities. In one lagoon, greater flamingo negatively affected Ruppia cirrhosa Petagna cover from June to July, and dry biomass in July. In the other lagoon, greater flamingo and mute swan had a detrimental effect on Zostera noltii Hornemann cover at the beginning of the growing season (April). They also reduced Chaetomorpha sp. cover from April to July and dry biomass in July. Combined activities of waterbirds decreased the dominance of Chaetomorpha sp. bed, thus favouring later (July) Z. noltii cover and partially dry biomass in areas available for greater flamingo and mute swan. However, the impact of waterbirds was not entirely beneficial for Z. noltii, as its abundance during July was indeed higher in ungrazed areas with low Chaetomorpha sp. abundance in previous months. The combined effect of waterbirds on Z. noltii is thus dual, mainly favouring its development by reducing competing macroalgae but conversely mitigating it through direct impact at both ends of the growing season. Depending on the ecological context, waterbirds can thus affect in two opposite ways the growth of plant species such as Z. noltii or R. cirrhosa which are of importance with regard to conservation. Large waterbird species can be considered as ecosystem engineers in Mediterranean wetlands. © 2012 Elsevier B.V.

In this paper we present data on breeding parameters of Little Tern Sterna albifrons, Common Tern Sterna hirundo and Gull-billed Tern Sterna nilotica nesting in Sfax salina in south-eastern Tunisia. The abundance peak was reached between the end of April and the beginning of May for the Little Tern and Common Tern and during May for Gull-billed Tern. Egg laying started from the third to the fourth week of April for Little and Common Terns and across May for Gull-billed Tern. In the three years of study, the number of nests per colony varied from 1 to 75 for Little Tern, from 1 to 101 for Common Tern, and from 1 to 114 for Gullbilled Tern. Clutch size varied between 1 and 4 for Little and Common Terns and from 1 to 3 for Gull-billed Tern, with significant differences among years. For the three species, the colony reproductive success, i.e. the number of fledged chicks per breeding pair, largely varied among colonies and years. Lowest and highest recorded values were 0 and 1.8 for Little Tern; 0 and 2 for Common Tern, and 0 and 0.8 for Gull-billed Tern. This low reproductive success is thought to be mainly caused by terrestrial predation and disturbance.

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