Sanz-Aguilar Ana, Tavecchia Giacomo, Afán Isabel, Ramírez Francisco, Doxa Aggeliki, Bertolero Albert, Gutiérrez-Expósito Carlos, Forero Manuela G, Oro Daniel
Department of Conservation Biology, Estación Biológica de Doñana (CSIC), Sevilla, Spain; Population Ecology Group, Institut Mediterrani d'Estudis Avançats, IMEDEA (CSIC-UIB), Esporles, Spain.
Population Ecology Group, Institut Mediterrani d'Estudis Avançats, IMEDEA (CSIC-UIB), Esporles, Spain.
PLoS One. 2014 Mar 24;9(3):e92674. doi: 10.1371/journal.pone.0092674. eCollection 2014.
Small and peripheral populations are typically vulnerable to local extinction processes but important for the metapopulation dynamics of species. The Slender-billed gull (Chroicocephalus genei) is a long-lived species breeding in unstable ephemeral coastal habitats. Their Western Mediterranean populations are relatively small and represent the edge of their global geographical distribution. At a local scale, using long-term data (14 years) on annual breeding success and capture-resights of marked individuals, we estimated and compared the vital rates and evaluated the connectivity of two Spanish populations (Ebro Delta and Doñana) varying in their local environmental conditions. At a metapopulation scale, we analyzed 22 years of data on breeding numbers to predict their future prospects by means of population demographic models. Local survival and breeding success of gulls from the Ebro Delta was lower than those from Doñana, which is likely the result of higher permanent emigration and/or winter mortality in the former. Gulls from the Ebro Delta wintered mostly in Mediterranean areas whereas those from Doñana did so in Atlantic coasts, where food availability is higher. Whereas adult local survival was constant, juvenile local survival showed temporal parallel variations between colonies, probably related to natal dispersal to other breeding colonies. Our results suggested that dispersal was higher at the Ebro Delta and gulls emigrating from their natal colonies settled preferentially in close patches. We found large fluctuations in breeding numbers among local populations probably related to the fact that the Slender-billed gull is a species adapted to unstable and unpredictable habitats with high abilities to disperse between suitable patches depending on environmental stochastic conditions during breeding.
小型和边缘种群通常易受局部灭绝过程的影响，但对物种的集合种群动态至关重要。细嘴鸥（Chroicocephalus genei）是一种长寿物种，在不稳定的临时性沿海栖息地繁殖。其西地中海种群相对较小，代表了其全球地理分布的边缘。在局部尺度上，我们利用关于年度繁殖成功率和标记个体重捕的数据（14年），估计并比较了两个西班牙种群（埃布罗三角洲和多尼亚纳）的生命率，并评估了它们在当地环境条件下的连通性。在集合种群尺度上，我们分析了22年的繁殖数量数据，通过种群统计模型预测它们的未来前景。埃布罗三角洲的鸥类的局部存活率和繁殖成功率低于多尼亚纳的鸥类，这可能是前者永久迁出率较高和/或冬季死亡率较高的结果。埃布罗三角洲的鸥类大多在地中海地区越冬，而多尼亚纳的鸥类则在食物供应更丰富的大西洋沿岸越冬。虽然成年鸥类的局部存活率保持不变，但幼鸟的局部存活率在不同繁殖地之间呈现出时间上的平行变化，这可能与向其他繁殖地的出生扩散有关。我们的结果表明，埃布罗三角洲的扩散率较高，从出生繁殖地迁出的鸥类优先定居在附近的斑块中。我们发现局部种群的繁殖数量有很大波动，这可能与细嘴鸥是一种适应不稳定和不可预测栖息地的物种有关，它们具有根据繁殖期间的环境随机条件在适宜斑块之间高效扩散的能力。
