1. Camera traps deployed in grids or stratified random designs are a well‐established survey tool for wildlife but there has been little evaluation of study design parameters.
2. We used an empirical subsampling approach involving 2,225 camera deployments run at 41 study areas around the world to evaluate three aspects of camera trap study design (number of sites, duration and season of sampling) and their influence on the estimation of three ecological metrics (species richness, occupancy and detection rate) for mammals.
3. We found that 25–35 camera sites were needed for precise estimates of species richness, depending on scale of the study. The precision of species‐level estimates of occupancy (ψ) was highly sensitive to occupancy level, with <20 camera sites needed for precise estimates of common (ψ > 0.75) species, but more than 150 camera sites likely needed for rare (ψ < 0.25) species. Species detection rates were more difficult to estimate precisely at the grid level due to spatial heterogeneity, presumably driven by unaccounted habitat variability factors within the study area. Running a camera at a site for 2 weeks was most efficient for detecting new species, but 3–4 weeks were needed for precise estimates of local detection rate, with no gains in precision observed after 1 month. Metrics for all mammal communities were sensitive to seasonality, with 37%–50% of the species at the sites we examined fluctuating significantly in their occupancy or detection rates over the year. This effect was more pronounced in temperate sites, where seasonally sensitive species varied in relative abundance by an average factor of 4–5, and some species were completely absent in one season due to hibernation or migration.
4. We recommend the following guidelines to efficiently obtain precise estimates of species richness, occupancy and detection rates with camera trap arrays: run each camera for 3–5 weeks across 40–60 sites per array. We recommend comparisons of detection rates be model based and include local covariates to help account for small‐scale variation. Furthermore, comparisons across study areas or times must account for seasonality, which could have strong impacts on mammal communities in both tropical and temperate sites.

中文翻译：

---

相机陷阱研究设计的实证评估：多少，多少时间和时间？

1. 部署在网格或分层随机设计中的相机陷阱是一种成熟的野生动植物调查工具，但对研究设计参数的评估很少。
2. 我们使用了经验二次抽样方法，涉及在全球41个研究区域运行的2,225台摄像机，评估了摄像机陷阱研究设计的三个方面（地点数量，采样的持续时间和季节）及其对估计三个生态指标（物种）的影响丰富度，占有率和检出率）。
3. 我们发现，根据研究规模的不同，需要25–35个摄像头站点来精确估计物种丰富度。物种水平占用率估计值的精确度对占用率高度敏感，对于常见物种（ψ> 0.75）的精确估计，需要<20个摄像头位置，而稀有物种（ψ<0.75 0.25）种。由于空间异质性，物种检出率更难以在网格水平上精确估计，这大概是由于研究区域内生境变异性因素无法确定。在现场运行相机2周对于检测新物种最有效，但是精确估计本地检测率需要3-4周，而在1个月后未观察到精度的提高。所有哺乳动物群落的指标都对季节敏感，在我们调查的地区中，有37％–50％的物种在一年中的占有率或发现率波动很大。这种影响在温带地区更为明显，在这些地区，季节性敏感物种的相对丰度平均差异为4-5，而某些物种由于冬眠或迁徙而在一个季节内完全消失。
4. 我们建议遵循以下准则，以利用相机陷阱阵列高效准确地获取物种丰富度，占有率和检测率的估计值：每个相机在每个阵列40-60个站点中运行3-5周。我们建议比较检测率应基于模型，并包括局部协变量以帮助解决小范围的变化。此外，研究区域或时间之间的比较必须考虑季节性因素，这可能会对热带和温带地区的哺乳动物群落产生重大影响。