Abstract Context. Non-invasive sampling methods are widely used by ecologists to collect animal hair, images, tissue or signs. Sampling devices are imperfect, and collection success may vary over time owing to behavioural changes in study organisms or other factors. If collection success decreases, the utility of non-invasive sampling devices for longitudinal studies that rely on consistency may be compromised. Aims. Our primary objectives were to evaluate whether collection success of brown bear (Ursus arctos) hair by using hair snares and camera traps changed over time, and whether hair- and image-collection success was influenced by bear activity around the sampling site. Methods. We paired non-invasive sampling by hair snares with motion-activated cameras at six streams in Alaska over 4–6 years, so as to evaluate how often brown bears left samples on wires or were photographed by cameras, and whether this sampling success changed over time. Changes in sampling success were evaluated in the context of bear activity per sampling period as determined by camera data (number of bear–wire encounters) or hair snare (number of barbs with hair); genetic analyses allowed us to evaluate whether the same bears were sampled repeatedly. Key results. Overall, hair was collected in 78% and images in 73% of 2-day sampling periods when bears visited sites, and we observed no substantial change in the probability of successful sampling over time at 11 sites. The number of bear–wire encounters was positively correlated with the number of hair samples collected, as would be expected if sampling rates remained constant over time, and individual bears with previous wire experience were sampled in multiple years. Conclusions. Overall, the results indicated that sampling success by using hair snare and camera trap showed substantial interannual variability, but changes over time were not consistently identified across sites. Among-site variation in sampling success highlighted the importance of accounting for site-specific differences in sampling success, and neither method sampled unfailingly. Implications. Sampling by wires and cameras remained effective over time, suggesting that these non-invasive sampling methods may be successfully employed in long-term studies.

中文翻译：

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长期使用无创采样方法：毛圈和相机陷阱对棕熊的成功采样是否会随着时间的推移而改变？

摘要上下文。生态学家广泛使用非侵入性采样方法来收集动物毛发、图像、组织或迹象。采样设备不完善，由于研究生物体的行为变化或其他因素，收集成功可能会随着时间的推移而变化。如果采集成功率下降，则依赖于一致性的纵向研究的非侵入性采样设备的效用可能会受到影响。目标。我们的主要目标是评估使用毛发圈套和相机陷阱收集棕熊 (Ursus arctos) 毛发的成功率是否随时间变化，以及毛发和图像收集成功是否受到采样地点周围熊活动的影响。方法。在 4-6 年的时间里，我们在阿拉斯加的 6 条溪流中将头发圈套的非侵入性采样与运动激活相机配对，以便评估棕熊将样本留在电线上或被相机拍摄的频率，以及这种采样成功率是否随时间变化。采样成功率的变化是在每个采样周期的熊活动背景下评估的，由相机数据（熊线遇到的数量）或毛发圈套（带毛发的倒钩数量）确定；基因分析使我们能够评估是否对相同的熊进行了重复采样。关键结果。总体而言，当熊访问站点时，在 78% 的 2 天采样期间收集了 78% 的毛发和 73% 的图像，并且我们观察到在 11 个站点成功采样的概率随着时间的推移没有实质性变化。遇到熊线的次数与收集的头发样本数量呈正相关，如果采样率随时间保持不变，则可以预期，并且在多年内对具有先前接线经验的个体熊进行了采样。结论。总体而言，结果表明，使用毛发圈套和相机陷阱的采样成功显示出显着的年际变化，但在不同地点并没有一致地识别出随时间的变化。采样成功率的站点间差异强调了考虑采样成功率的站点特定差异的重要性，并且两种方法都不会无误地进行采样。影响。随着时间的推移，通过电线和相机进行采样仍然有效，这表明这些非侵入性采样方法可能会成功地用于长期研究。但随着时间的推移，站点之间的变化并没有得到一致的识别。采样成功率的站点间差异强调了考虑采样成功率的站点特定差异的重要性，并且两种方法都不会无误地进行采样。影响。随着时间的推移，通过电线和相机进行采样仍然有效，这表明这些非侵入性采样方法可能会成功地用于长期研究。但随着时间的推移，站点之间的变化并没有得到一致的识别。采样成功率的站点间差异强调了考虑采样成功率的站点特定差异的重要性，并且两种方法都不会无误地进行采样。影响。随着时间的推移，通过电线和相机进行采样仍然有效，这表明这些非侵入性采样方法可能会成功地用于长期研究。