Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula
Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula
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DOI：
10.1111/j.1365-2699.2010.02377.x
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发表时间：
2010-12-01
影响因子：
3.9
通讯作者：
Delibes, Miguel
中科院分区：
文献类型：
--
作者：
Clavero, Miguel;Hermoso, Virgilio;Delibes, Miguel
AimTo determine the relationships between otter（Lutra lutra）distribution dynamics and environmental and spatial constraints over a 20-year period.LocationAndalusia，southern Iberian半岛岛.MethodsWe synthesized otter distribution data from three otter survey（1985，1995 and 2005）using sub-category areas defined by hydrogenic barriers.集水区的特点是两个“自然”（气候和地形变量）和两个“人类”（土地利用和人口密度）梯度。此外，我们计算了两个传染性变量（距离以前占用的子集水区和占用子集水区的百分比在50公里的缓冲区）连续调查subcatchments.ResultsBetween 1985年和2005年的子集水区与水獭本的百分比从42%增加到72%。水獭在人类占主导地位的地区往往很少见或不存在。与自然梯度相比，人为梯度对水獭分布有更好的预测作用。人类和自然梯度表现出很强的协变，但对于任何自然梯度值水獭往往存在于子流域较低的人类影响。新的子集水区的殖民化被认为是密切相关的传染变量和扩张速度慢于其他研究中估计。新殖民地的地区往往位于中间的人类影响的地区，而反复缺席主要发生在人类影响最严重的地区。主要conclusionsOur研究结果表明，最近整个安达卢西亚水獭扩张是一个大规模改善环境条件的反映。水獭种群的生存时期的强大和普遍的下降似乎是作为来源，从邻近地区的殖民地，可能有助于改善水质和增加粮食供应。然而，水獭进一步扩大到其全部原始范围可能会受到人类影响的景观的限制。
AimTo determine the relationships between otter (Lutra lutra) distribution dynamics and environmental and spatial constraints over a 20-year period.LocationAndalusia, southern Iberian Peninsula.MethodsWe synthesized otter distribution data from three otter surveys (1985, 1995 and 2005) using subcatchment areas defined by hydrological barriers. Subcatchments were characterized by two 'natural' (climatic and orographic variables) and two 'human' (land use and population density) gradients. In addition, we calculated two contagion variables (the distance to previously occupied subcatchments and the percentage of occupied subcatchments within a 50 km buffer) for consecutively surveyed subcatchments.ResultsBetween 1985 and 2005 the percentage of subcatchments with otters present increased from 42% to 72%. Otters tended to be rare or absent from human-dominated areas. Anthropogenic gradients were better predictors of otter distribution than natural ones. Human and natural gradients showed strong covariation, but for any value of the natural gradients otters tended to be present in subcatchments with lower human impacts. Colonization of new subcatchments was found to be strongly related to contagion variables and expansion rates were slower than those estimated in other studies. Newly colonized areas tended to be located in areas with intermediate human influence, while repeated absences occurred mainly in areas where human impact was most severe.Main conclusionsOur results suggest that recent otter expansion across Andalusia is a reflection of large-scale improvement in environmental conditions. Otter populations that survived the period of strong and generalized declines appear to be acting as sources from which neighbouring areas are colonized, probably aided by improved water quality and increases in food availability. However, the further expansion of otters into their full original range is likely to be constrained by human-impacted landscapes.