Detection probability is an important input when studying and managing species. It reduces the miscalculations of the estimates of occupancy, population abundances and their trends inherent to the imperfect detection during sampling. However, detection probability may vary in relation to environmental and biological factors, such as the presence of other species of similar ecological niche. We used a two-species single-season occupancy model to analyse the detection probability of the native Eurasian otter Lutra lutra and the invasive American mink Neovison vison in the northeast of the Iberian Peninsula and to test for potential differences in their detection when co-occurring and when not. Despite the known behavioural change of American mink towards a more terrestrial diet and a more diurnal activity pattern in the presence of Eurasian otter, their detectability did not vary when both species co-occurred versus when they did not. However, we observed seasonal differences in the probability of detection. Specifically, the probability of detection was higher in winter for both species. Furthermore, Eurasian otter was more often detected in sites with clay substrate, whereas American mink in sites with clay and rocks. These results indicate that the effectiveness of monitoring of Eurasian otter and American mink remains independent of the species co-occurrence. Yet, seasonal variations in the detection should be taken into account when monitoring.

中文翻译：

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欧亚水獭和入侵性美国水貂的检测概率与它们的共现无关

在研究和管理物种时，检测概率是重要的输入。它减少了对采样率，人口数量估计值的错误估计以及采样期间检测不完善所固有的趋势。但是，检测概率可能会随环境和生物学因素（例如存在类似生态位的其他物种）而变化。我们使用了两个物种的单季节占用模型来分析欧亚水獭Lutra lutra和入侵性美国水貂Neovison vison的检测概率并在伊比利亚半岛东北部进行测试，以检测是否同时出现或未出现时它们的检测可能存在的差异。尽管已知美式水貂在欧亚水獭的存在下会朝着更陆地化的饮食和更昼夜的活动方式改变行为，但是当两种物种同时出现时，它们的可检测性没有变化。但是，我们发现了检测概率的季节性差异。具体而言，两种物种在冬季的检出概率均较高。此外，欧亚水獭更常见于带有粘土基质的地方，而美国貂皮则位于带有粘土和岩石的地方。这些结果表明，监测欧亚水獭和美国水貂的有效性仍然与物种共生无关。然而，