Abstract Reducing threats to biodiversity is the key objective of ranger patrols in protected areas. However, efforts can be hampered by rangers' inability to detect threats, and poor understanding of threat abundance and distribution in a landscape. Snares are particularly problematic due to their cryptic nature and limited selectivity with respect to captured animals' species, sex, or age. Using an experimental approach, we investigated the effect of search effort, habitat, season, and team on rangers' detection of snares in a tropical forest landscape. We provide an effort-detection curve, and use our findings to make preliminary predictions about snare detection under different scenarios of patrol effort. Results suggest that the overall probability of a searcher detecting any given snare in a 0.25/km2 area, assuming 60 min (or approximately 2 km) of search effort is 20% (95% CI ± 15–25%), with no significant effect of season, habitat or team. Our models suggested this would increase by approximately 10% with an additional 30mins/1 km of search effort. Our preliminary predictions of the effectiveness of different patrolling scenarios show that detection opportunities are maximised at low effort levels by deploying multiple teams to a single area, but at high effort levels deploying single teams becomes more efficient. Our results suggest that snare detectability in tropical forest landscapes is likely to be low, and may not improve dramatically with increased search effort. Given this, managers need to consider whether intensive snare-removal efforts are the best use of limited resources; the answer will depend on their underlying objectives.

中文翻译：

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实验评估搜索努力对圈套可探测性的影响

摘要 减少对生物多样性的威胁是保护区护林员巡逻的主要目标。然而，由于护林员无法检测威胁以及对景观中威胁的丰富度和分布的了解不足，工作可能会受到阻碍。由于圈套的隐秘性和对捕获动物的物种、性别或年龄的有限选择性，圈套尤其成问题。我们使用实验方法研究了搜索工作、栖息地、季节和团队对热带森林景观中护林员检测陷阱的影响。我们提供了努力检测曲线，并使用我们的发现对不同巡逻努力场景下的圈套检测做出初步预测。结果表明，搜索者在 0.25/km2 区域内检测到任何给定圈套的总体概率，假设 60 分钟（或大约 2 公里）的搜索工作是 20%（95% CI ± 15–25%），季节、栖息地或团队没有显着影响。我们的模型表明，如果搜索工作增加 30 分钟/1 公里，这将增加大约 10%。我们对不同巡逻场景有效性的初步预测表明，通过将多个团队部署到单个区域，可以在低工作级别下最大限度地提高检测机会，但在高工作级别部署单个团队会变得更有效率。我们的结果表明，热带森林景观中的圈套可探测性可能较低，并且可能不会随着搜索工作的增加而显着提高。鉴于此，管理人员需要考虑密集的除网罗工作是否是对有限资源的最佳利用；答案将取决于他们的基本目标。