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Studies on the behaviour of grey squirrels Sciurus carolinensis Gmelin, 1788 and other species belonging to the same genus, suggest they exhibit dominance hierarchies among both males and females, and their mating strategy is promiscuous or polygynous, However, there is little information available on how dominance translates into repro­ductive success or on the levels of genetic variation or genetic substructuring within a population. To address these questions, we used multilocus DNA fingerprinting to quantify genetic diversity and estimate relatedness amongst individuals in a free­-ranging population of grey squirrels. Background band-sharing values revealed a high degree of genetic diversity existed. The frequency distribution of band-sharing values between known first order relatives and presumed unrelated animals was significantly different. Estimates of relatedness between individuals were therefore based on threshold levels of genetic similarity and used as a tool to infer close kinship. Possible kinship groups were identified using the spatial distribution of the home ranges of adults and juveniles. Levels of relatedness between neighbouring adults was low with five family units identified comprised of putative parents and their offspring. Several juveniles from the single cohort revealed levels of relatedness intermediate between first order relatives and unrelated animals, suggesting possible second order relationships (eg half siblings) existed. The implications of these relationships are discussed.
Camera trapping has been widely applied to studies of medium to large terrestrial mammals, but its application to small arboreal mammals has hardly been tested. We employed camera trapping and other conventional monitoring methods during a mammal survey in a Site of Community Importance located within the Adda North Regional Park (Lombardy, Italy). Camera trapping was particularly successful for monitoring arboreal mammals, allowing the first detection of presence of the invasive grey squirrel (Sciurus carolinensis) in an area occupied by indigenous red squirrels (Sciurus vulgaris) and the collection of a large amount of data on squirrels and common dormice (Muscardinus avellanarius). When triggered, cameras were set to record short video clips (10 to 40 s). More than 400 events were recorded and analysed, mainly from the autumn and winter months. The daily activity pattern of both species displayed a trend from two to three activity peaks in summer to a unimodal pattern in winter, with the peaks of the two species temporally separated. Camera trapping could be a useful method also when applied to monitoring small mammals, particularly endangered arboreal or invasive alien species. For instance, the monitoring of the spread of S. carolinensis is particularly important, where the early detection of new population can be crucial for the conservation of indigenous European species. Camera trapping can be an effective addition to traditional survey methods. It provides a simple non-invasive technique for collecting a large amount of data per device with limited human effort.
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