Dispersal is a fundamental process in ecology because it influences the dynamics, genetic structure and persistence of populations. Furthermore, understanding the evolutionary causes of dispersal pattern, particularly when they differ between genders, is still a major question in evolutionary ecology. Using a panel of 10 microsatellite loci, we investigated at different spatial scales the genetic structure and the sex-specific dispersal patterns in the common vole Microtus arvalis, a small colonial mammal. This study was conducted in an intensive agricultural area of western France. Hierarchical F ST analyses, relatedness and assignment tests suggested (i) that females are strongly kin-clustered within colonies; (ii) that dispersal is strongly male-biased at a local scale; and (iii) long-distance dispersal is not rare and more balanced between genders. We conclude that males migrate continuously from colony to colony to reproduce, whereas females may disperse just once and would be mainly involved in new colony foundation.

Studies on the role of introduced rabbits, Oryctolagus cuniculus, on islands have mainly focused on their negative impacts on vegetation. However, little attention has been paid to their influence on vertebrate communities. On Ile Verte (148 ha) in the sub-Antarctic Kerguelen Archipelago, rabbits are the only mammal that have been introduced. The long-term consequences of their eradication in 1992 on both native, burrowing seabird prey populations and their predator, the brown skua Catharacta skua, were investigated between 1991 and 2005. Densities of breeding petrels were followed on site with three plant communities differing in their soil depth. In addition, the diet and breeding activities of skuas were evaluated on the entire island area. The density of breeding pairs of the most abundant petrel species, the blue petrel Halobaena caerulea, which only nested at the site with deepsoil, increased by approximately eightfold during the 6 years following the rabbit eradication. Of the other species nesting in deep soil, there was an approximately fourfold reduction in the Antarctic prion, Pachyptila desolata, but such a decrease in breeding pair densities was not observed in areas with shallow soils. The SouthGeorgian diving petrels, Pelecanoides georgicus, was the rarest species, nesting only on mineral soils, and for which breeding pairs did not vary through time. The total numbers of fledged chicks of skua on the island significantly increased during the study period, but not the total number of breeding pairs. Thus, brown skuas were not affected by the disappearance of rabbits and rather benefited from an increase of their preferred prey. Blue petrels recovered quickly to sites with deepsoil, benefiting from the rabbit eradication and the cessation of burrow disturbance. The decrease of Antarctic prions could have been the result of an exclusion process from nesting areas on the deep soil site by blue petrels.

No abstract

For the past 20 years, different policy and regulatory tools such as the agrienvironment schemes (AES) and the Natura 2000 network have been used in Europe to halt the ongoing decline of farmland birds resulting from agricultural intensification. Despite their wide implementation, bird populations are still declining at national and European scales, thus questioning the effectiveness of these schemes. Here, we examined the impact of the designation in 2004 of a Special Protection Area (SPA) for the little bustard on the local trends of two non-targeted, common but declining farmland birds, the skylark and the corn bunting, in an intensive arable landscape of western France. From 1996 to 2012, trends in skylark presence or abundance decreased whereas trends in corn bunting abundance first decreased and then showed a recovery; the trends differed between outside and inside the SPA. Outside the SPA and consistently with trends at the national and European scales, skylark abundance sharply decreased whereas corn bunting abundance first decreased and then stabilized or even slightly increased. Within the SPA, the skylark declined less, and the corn bunting abundance increased at a faster rate than outside. Our results suggest that the implementation of a SPA in this arable landscape had a positive impact on these two farmland passerines, at least for corn buntings, for which the implementation of AES clearly improved habitat. Our results also suggest that the extensive implementation of SPAs may have had a positive impact on bird population trends in farmlands at a regional level, where c. 150 000 ha (15-20% of total arable landscape) have been designated since 2004. However, the SPA network (within Natura 2000) currently covers a mere 3.7% of French arable landscape, and it is therefore no surprise that specialist birds in farmland are still declining nationally. bs_bs_banner Animal Conservation. Print