Abstract Context The niche reduction hypothesis (NRH) predicts that the realised niche of declining species is reduced by threats that are mediated by environmental, biotic and evolutionary processes, explaining why species decline in some locations but not others. The critically endangered central rock-rat (CRR) survives only in rugged mountain range habitat in central Australia and is highly vulnerable to cat predation. We predicted that cat density and ranging behaviour, and, hence, predation risk, is mediated by habitat complexity, thus explaining the mechanism maintaining the CRR refuge. Aims We sought to determine whether cat densities were lower in the rugged CRR refuge than in an adjacent valley dominated by less complex rocky habitats and no longer occupied by CRRs. Methods We installed arrays of camera traps along two parallel mountain ranges in the refuge and in the intervening valley habitats. We identified uniquely patterned individual cats and compared spatially explicit capture–recapture (SECR) models to evaluate our hypothesis that cat density varies with topographic complexity. Key results The dominant effect in all models was the significant negative relationship between cat detection probability and fine-scale topographic ruggedness. Two of the best three SECR models indicated lower cat densities and relative home-range sizes in the refuge than in the valley. In total, 17% of cats were detected in both habitat types. Conclusions We found some evidence that cat density and home-range size were mediated by habitat complexity. Further, the negative relationship between cat detection probability and topographic complexity suggests that cats spend less time foraging in CRR refuge habitat. Implications Cat management programs, aimed at reducing predation pressure on the CRR, must include the refuge and surrounding habitats to control cats that pose a threat to CRR subpopulations.

中文翻译：

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地形复杂性可能会调节极度濒危啮齿动物的猫捕食风险

摘要背景生态位减少假说（NRH）预测，环境、生物和进化过程介导的威胁减少了正在减少的物种的已实现生态位，这解释了为什么物种在某些地方减少而不是其他地方减少。极度濒危的中央岩鼠 (CRR) 仅在澳大利亚中部崎岖的山脉栖息地生存，并且极易受到猫的捕食。我们预测猫的密度和测距行为以及捕食风险是由栖息地复杂性介导的，从而解释了维持 CRR 避难所的机制。目标 我们试图确定崎岖的 CRR 避难所中的猫密度是否低于邻近山谷中的猫密度，该山谷由不太复杂的岩石栖息地主导，不再被 CRR 占据。方法 我们沿着避难所和中间山谷栖息地的两个平行山脉安装了一系列相机陷阱。我们确定了独特图案的个体猫，并比较了空间显式捕获 - 重新捕获 (SECR) 模型，以评估我们的假设，即猫密度随地形复杂性而变化。主要结果 所有模型中的主要影响是猫检测概率与细尺度地形坚固性之间的显着负相关。三个最好的 SECR 模型中的两个表明，避难所中的猫密度和相对家庭范围的大小比山谷中的低。在这两种栖息地类型中，总共检测到 17% 的猫。结论我们发现了一些证据表明猫密度和家庭范围的大小是由栖息地复杂性介导的。更多，猫发现概率与地形复杂性之间的负相关表明猫在 CRR 避难栖息地觅食的时间较少。影响 旨在减少 CRR 捕食压力的猫管理计划必须包括避难所和周围栖息地，以控制对 CRR 亚群构成威胁的猫。