du Rau P.D.,CNERAavifaune migratrice |
Bourgeois K.,University of Auckland |
Bourgeois K.,Aix - Marseille University |
Thevenet M.,Conservatoire du Littoral |
And 19 more authors.
Journal of Ornithology | Year: 2015
Scopoli’s Shearwater (Calonectris diomedea) is a Procellariiform endemic to the Mediterranean Basin which is considered to be vulnerable in Europe due to recent local declines and its susceptibility to both marine and terrestrial threats. In the 1970s–1980s, its population size was estimated at 57,000–76,000 breeding pairs throughout the Mediterranean Basin, with the largest colony, estimated at 15,000–25,000 pairs, found on Zembra Island, Tunisia. The objectives of our study were to re-estimate the size of the breeding population on Zembra Island, to reassess the global population size of the species, and to analyse the implications of these findings on status and conservation of this species in the Mediterranean. Using distance sampling, we estimated the Zembra breeding population to be 141,780 pairs (95 % confidence interval 113,720–176,750 pairs). A review of the most recent data on populations of this species throughout the Mediterranean Basin led us to estimate its new global population size at 141,000–223,000 breeding pairs. Using the demographic invariant and potential biological removal approaches, we estimated the maximum number of adults which could be killed annually by all non-natural causes without causing a population decline to be 8800 (range 7700–9700) individuals, of which could be 3700 breeders. Although these results are less alarming in the context of species conservation than previously thought, uncertainties associated with global population size, trends and major threats still raise questions on the future of this species. More generally, we show how a monitoring strategy for a bird supposed to be relatively well known overall can be potentially misleading due to biases in survey design. The reduction of such biases would therefore appear to be an unavoidable prerequisite in cryptic species monitoring before any reliable inference on the conservation status of the species can be drawn. © Dt. Ornithologen-Gesellschaft e.V. 2015
Gremillet D.,French National Center for Scientific Research |
Gremillet D.,University of Cape Town |
Peron C.,French National Center for Scientific Research |
Peron C.,Australian Antarctic Division |
And 5 more authors.
Marine Biology | Year: 2014
Recent meta-analyses identified conservation hotpots at the scale of the Mediterranean, yet those may be crude by lack of detailed information about the spatial ecology of the species involved. Here, we identify an irreplaceable marine area for >95 % of the world population of the Scopoli’s shearwater (Calonectris diomedea), which is endemic to the Mediterranean and breeds on the island of Zembra off Tunis. To this end, we studied the three-dimensional at-sea movements of 50 breeding adults (over a total of 94 foraging trips) in 2012 and 2013, using GPS and temperature–depth recorders. Feathers were also collected on all birds to investigate their trophic status. Despite Zembra being the largest seabird colony in the Mediterranean (141,000 pairs), the per capita home-range of Scopoli’s shearwaters foraging from this colony was not larger than that of birds from much smaller colonies, indicating highly beneficial feeding grounds in the Gulf of Tunis and off Cap Bon. Considering depleted Mediterranean small pelagic fish stocks, supposed to be Scopoli’s shearwater prey base, we therefore speculate that birds may now also largely feed on zooplankton, something which is supported by our stable isotopic analyses. Crucially, shearwater at-sea feeding and resting areas showed very little overlap with a conservation hotspot recently defined on the western side of the Gulf of Tunis using meta-analyses of species distributions relative to anthropogenic threats. We therefore propose a major extension to this conservation hotspot. Our study stresses the importance of detailed biotelemetry studies of marine megafauna movement ecology for refining large-scale conservation schemes such as marine protected area networks. © 2014, Springer-Verlag Berlin Heidelberg.
Tlili W.,Tunis el Manar University |
Nefla A.,Tunis el Manar University |
Delaugerre M.,Conservatoire du littoral |
Ouni R.,Wildlife Conservation Society |
Nouira S.,Tunis el Manar University
Acta Herpetologica | Year: 2014
Tunisian geckos count nine species (1 is insular relict, 1 is endemic, 2 are ubiquitous and 5 are enfeoffed). We aim to determine factors influencing their distributions. Surveys were founded on environmental divisions. Presence/ absence data for 113 grids were analyzed using multivariate tools. 18 environmental variables were revealed and clustered into five factors to model species distributions. Established models were further projected on non-explored areas within Tunisian territory. The distribution of continental geckos follows an indirect bidirectional gradient; the South-northward one is physiologically stressful and the North-southward one is biologically stressful. Five biogeographic regions were established showing concordance with climatic and vegetation regionalization. The distribution of non-anthropophilic species is positively correlated to thermal amplitudes gradient. The distribution of anthropophilic taxa is positively correlated to agricultural land-use. Oasis, sebkhas and chotts are particular landscapes that disturb both distributions. Predicted areas follow the yielded distribution patterns despite some discrepancy for S. sthenodactylus. The niche characterizing shows that land use and altitude increase the probability of occurrence of H. turcicus and T. mauritanica. Alternatively, they decrease the probability of the presence of T. deserti, T. neglecta, T. tripolitanus and S. petrii. Models could also show that the absence of S. sthenodactylus in northern regions is attributed to high altitudes and cereal land-use. As to T. fascicularis, the displacement of the northern limits of its range is mostly attributed to an improvement of field investigations. Established model of its distribution shows a restricted area of probable occurrence in central Tunisia confirming its endemism. © Firenze University Press.
Michel-Jean D.,Conservatoire du littoral
Acta Herpetologica | Year: 2013
Hierophis viridiflavus has a strong diurnal rhythm as demonstrated by many field studies. It belongs to the "Whip snakes" characterized by slender bodies, large eyes, high speed, saurophagy and diurnality. On Giraglia island (Corsica) the snakes do forage also nightly. This unexpected shift in the circadian rhythm might be related to a local adaptation to trophic requirements. © Firenze University Press.
Noel F.,Montpellier University |
Maurice S.,Montpellier University |
Mignot A.,Montpellier University |
Glemin S.,Montpellier University |
And 5 more authors.
Conservation Genetics | Year: 2010
Long-term demographic surveys, needed to obtain accurate information on population dynamics and efficiently manage rare species, are still very scarce. Matrix population models are useful tools to identify key demographic transitions and thus help setting up conservation actions. Furthermore, the combination of ecological, demographic and genetic data is likely to improve the identification of the threats acting upon populations and help conservation decisions. In this paper we illustrate the power of this approach on Brassica insularis, a Mediterranean endemic plant species, rare and endangered in Corsica (France). In four populations of this species, a long-term demographic survey (2000-2009), genetic analyses (in 2000 and 2009) and survey of ecological variables (climatic variables, competition and herbivory) were performed. By using both deterministic and stochastic matrix model analyses, we assessed the viability of each population and tested for both spatial and temporal variations in demographic vital rates. Populations exhibited differing demographic behaviours and environmental stochasticity occurred in populations. Significant correlations between climatic variables and vital rates were detected. Stochastic simulations suggested that three out of the four populations studied might present a high risk of extinction on the short-term and should actively be managed, or at least surveyed. It could be, however, that two of these populations are experiencing density-dependent regulation, rather than being declining. Microsatellite diversity was slightly reduced in a single population and similar in the three others, consistently with expectations based on population census size and geographic area, as well as with diversity at the S-locus observed in 2000. The combination of all data led to specific recommendations for managing each population. We discuss the implications for conservation of such a general approach. © 2010 Springer Science+Business Media B.V.
Ouni R.,Association de Sauvegarde du Patrimoine Environnemental et Naturel |
Durand J.-P.,Conservatoire dEspaces Naturels Provence Alpes Cote dAzur |
Serra J.M.,Species Protection Service |
Essetti I.,Wildlife Conservation Society |
And 2 more authors.
Alauda | Year: 2012
Possible breeding of European Storm Petrel Hydrobates pelagicus at Zembra Island, Tunisia. After investigations over five years, the first record of 6 individuals in late June 2012 suggests the possibility that this species breeds on Zembra and Zembretta archipelago in Tunisia.
Burgevin P.,Conservatoire du littoral
Wildfowl | Year: 2013
The Havre de Regnéville, France, is a major wintering site for the East Canadian High Arctic Light-bellied Brent Goose Branta bernicla hrota (LBBG) population, which winters mainly on well-known and well-studied sites along the Irish coast. This wintering site has very little eelgrass Zostera sp. available and the geese regularly feed on saltmarshes grazed by sheep. The Conservatoire du littoral is developing several studies to provide a better understanding of why LBBG use this site and to evaluate the possible effects of climate change on its habitat. In particular, the proposed study will analyse a potential conflict of interests between biodiversity and agricultural activity in the area, to provide tools for a better coexistence between the geese and sheep feeding on the saltmarshes. © Wildfowl and Wetlands Trust.