Vineyards,but not cities,are associated with lower presence of a generalist bird,the Common Blackbird(Turdus merula),in Western France

Background:Land-use change is one of the main drivers of the global erosion of biodiversity.In that context,it is crucial to understand how landscape characteristics drive the presence of rare endangered species.Nevertheless,it is also important to study common species in multiple habitats,because they represent a large proportion of biodiversity and are essential to maintain ecological functions.Interestingly,some habitats,as farmlands with permanent crops(e.g.vineyards),have been overlooked in the literature.Methods:In this study,we investigated the distribution of a widespread and common bird species,the Common Blackbird(Turdus merula),within and between the three main habitats of our study area(rural Western France).We specifically focused on(1)woodlands,(2)farmlands with a high vineyard coverage,and(3)moderately urbanized areas.Specifically,we aimed to assess the beneficial and detrimental effects of these habitats and their fine-scale composition on the presence of a common bird species,relying on a survey by point counts(nearly 100 locations).We studied the effects of habitats and gradients of fine-scale habitat composition on blackbird presence using logistic regression analyses.Results:Blackbirds were present in all studied habitats.However,their presence varied between habitats,being lower in vineyards than in woodlands and cities.In woodlands and cities,fine-scale analyses did not reveal any component driving the species'presence.However,we found that shrub and tree vegetation cover had a significant positive effect on blackbird presence in vineyards.Conclusions:Our results are in agreement with the definition of a generalist species.Interestingly,species distribution varied between habitats.The high presence of blackbirds in urban areas suggests that medium-sized cities,despite their artificialization,do not constrain the settlement of this former forest specialist and that green spaces may allow blackbirds to thrive in medium-sized cities.On the contrary,we found an impoverished presence of blackbirds in vineyards and a positive effect of vegetation on their presence in these landscapes.This suggests that permanent crops,and more generally farmlands,may impose important constraints to common species.Future studies should examine how to enhance biodiversity through agricultural management policies,especially in vineyards.

MARE研究项目1999～2006:关于项目管理的思考

引言 至少从20世纪80年代开始，波罗的海的富养化就引起了波罗的海地区国家的极大关注。1988年，在赫尔辛基委员会的部长级会议上，部长们同意在10年内将波罗的海的养分总输入削减50％。1998年，部长们认为，尽管1988年的会议启动了若干行动，但并未达到50％的目标，富养化仍然受到极大关注。他们还表态要开发共同合作研究项目，其中包括决策支持模型。