Estimates of population density are crucial for wild felid conservation and are commonly conducted using camera trapping. Spatially explicit capture-recapture (SCR) survey designs often use two cameras per station to photograph both flanks of a spotted felid to confirm identities. However, if the sampling grid is inadequate, and detector devices are unable to capture an animal’s complete movements, density may be overestimated. Density analyses incorporating identification inputs from both flanks derived from unpaired camera stations may offer a cost-effective solution by doubling the number of stations available to researchers. During 2008, we surveyed 164 sites for jaguars, ocelots, and bobcats using unpaired camera stations (mean trap nights per camera = 32.66, inter-trap distance = 800 m) on private ranching lands in Sonora, Mexico. We obtained 15, 52, and 229 detections of jaguars, ocelots, and bobcats from 9, 35, and 87 stations, respectively. SCR density estimates (individuals/100 km²) derived from a maximum likelihood multi-session model and a Bayesian spatial partial identity model (SPIM) were similar: 4.61 and 1.54 (jaguar), 4.66 and 4.33 (ocelot), and 15.22 and 15.88 (bobcat), respectively. Due to insufficient recaptures of jaguars, only SPIM provided a credible estimate of jaguar density. Jaguar density was one of the lowest reported across their distribution, which was expected given Sonora’s location at the periphery of the jaguar’s range. However, ocelot and bobcat populations appear to be healthy in Sonora, even within unprotected ranchlands. We recommend the use of SPIM to estimate the density of spotted felids with any dataset containing few recaptures in unpaired camera surveys.

中文翻译：

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墨西哥索诺拉州野生猫科动物的密度：空间显式捕获-捕获方法的比较

种群密度的估计对于野生猫科动物的保护至关重要，通常使用照相机诱捕技术进行。空间显式捕获-捕获（SCR）调查设计通常每个站点使用两个摄像头来拍摄斑点猫科动物的两个侧面，以确认身份。但是，如果采样网格不足，并且检测器设备无法捕获动物的完整运动，则密度可能会被高估。密度分析结合了来自未配对相机台的两个侧面的识别输入，可以通过使研究人员可用的台数加倍来提供一种经济高效的解决方案。在2008年期间，我们在墨西哥索诺拉岛的私人牧场上，使用不成对的照相站（美洲虎平均捕捉夜数= 32.66，诱捕器间距离= 800 m），对164个美洲虎，豹和山猫进行了调查。我们分别从9、35和87个站点获得了15次，52次和229次美洲虎，脚骨和山猫的检测。SCR密度估算（个人/ 100 km²）从最大似然多会话模型和贝叶斯空间部分身份模型（SPIM）派生而来的相似：分别为4.61和1.54（美洲虎），4.66和4.33（豹猫）以及15.22和15.88（山猫）。由于对美洲虎的捕获不足，只有SPIM提供了可靠的美洲虎密度估计。捷豹密度是整个分布中报告的最低密度之一，考虑到Sonora的位置位于捷豹范围的外围，这是可以预期的。然而，即使在未受保护的牧场内，索诺拉的豹猫和山猫种群似乎也很健康。我们建议使用SPIM来估计斑点猫科动物的密度，其中任何数据集在未配对的相机调查中都很少捕获。