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Eurasian otter (Lutra lutra) temporal and spatial ecology in Mediterranean streams
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Autores
Resumo(s)
Climate change poses a significant threat to global biodiversity, particularly in intermittent Mediterranean ecosystems, such as streams, by intensifying drought periods and flooding limiting water availability.The current study investigated the spatio-temporal patterns exhibited by Lutra lutra within riparian systems and the environmental and anthropogenic factors that may exert influence on these patterns. A total of 23 camera traps were set along mediterranean streams, 500 meters distance from each one, from October 2024 until June 2025. Temporal patterns of activity were estimated using kernel density estimators, Rayleigh tests, overlap coefficient analysis and Watson-Wheeler for test similarity in patterns between different environmental contexts. The evaluation of spatial patterns’ determinants was conducted using occupancy and N-Mixture models, which incorporated variables such as the physical characteristics of the stream, vegetation structure, and human disturbance. The results indicated trends in activity patterns, with otters showing a nocturnal behaviour with some variation according to the environmental context, although these trends did not reach statistical significance; these were elevated activity levels during nocturnal periods coinciding with periods of reduced moonlight, more intense and brief activity peaks in cold periods, and adjustments in activity times in response to human disturbance. The spatial detection process was found to be influenced by various environmental factors, including the depth and width of the stream, riverbank height, and extent of canopy cover, but none of the tested drivers seemed to affect the occupancy patterns contrarily to the presence of fallen logs that was found to be positively correlated with the abundance of otters. These fallen logs provided structures that facilitated hunting, movement, rest, and recreation behaviours. The results demonstrated the species' capacity for adaptation to diverse environmental conditions and provided indispensable information for conservation strategies, thereby contributing to the sustainable management of streams and the preservation of this species and local biodiversity.
Descrição
Tese de mestrado, Biologia da Conservação, 2026, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
activity patterns spatial patterns climate change riparian systems environmental variability