Post-Graduate Programme in Wildlife Biology and Conservation, Wildlife Conservation Society, India Program, National Centre for Biological Sciences (Tata Institute of Fundamental Research), Bangalore, India; Centre for Wildlife Studies, Bangalore, India.
Centre for Wildlife Studies, Bangalore, India; Wildlife Conservation Society, Bronx, New York, United States of America.
PLoS One. 2014 Jun 3;9(6):e98803. doi: 10.1371/journal.pone.0098803. eCollection 2014.
Although they play a critical role in shaping ecological communities, many threatened predator species are data-deficient. The Dhole Cuon alpinus is one such rare canid with a global population thought to be <2500 wild individuals. We assessed habitat occupancy patterns of dholes in the Western Ghats of Karnataka, India, to understand ecological and anthropogenic determinants of their distribution and habitat-use. We conducted spatially replicated detection/non-detection surveys of dhole signs along forest trails at two appropriate scales: the entire landscape and a single wildlife reserve. Landscape-scale habitat occupancy was assessed across 38,728 km(2) surveying 206 grid cells of 188-km(2) each. Finer scale habitat-use within 935 km2 Bandipur Reserve was studied surveying 92 grid cells of 13-km(2) km each. We analyzed the resulting data of dhole signs using likelihood-based habitat occupancy models. The models explicitly addressed the problematic issue of imperfect detection of dhole signs during field surveys as well as potential spatial auto-correlation between sign detections made on adjacent trail segments. We show that traditional 'presence versus absence' analyses underestimated dhole habitat occupancy by 60% or 8682 km2 [naïve = 0.27; ψL(SE) = 0.68 (0.08)] in the landscape. Addressing imperfect sign detections by estimating detection probabilities [p(t)(L) (SE) = 0.12 (0.11)] was critical for reliable estimation. Similar underestimation occurred while estimating habitat-use probability at reserve-scale [naïve = 0.39; Ψs(SE) = 0.71 (0.06)]. At landscape scale, relative abundance of principal ungulate prey primarily influenced dhole habitat occupancy. Habitat-use within a reserve, however, was predominantly and negatively influenced by anthropogenic disturbance. Our results are the first rigorous assessment of dhole occupancy at multiple spatial scales with potential conservation value. The approach used in this study has potential utility for cost-effectively assessing spatial distribution and habitat-use in other species, landscapes and reserves.
尽管它们在塑造生态群落方面发挥着关键作用，但许多受到威胁的捕食者物种的数据仍然不足。豺犬 Cuon alpinus 就是这样一种稀有的犬科动物，全球种群数量据估计<2500 只野生个体。我们评估了印度卡纳塔克邦西高止山脉豺犬的栖息地占有模式，以了解其分布和栖息地利用的生态和人为决定因素。我们在两个适当的尺度上沿森林小径进行了空间复制的豺犬踪迹检测/未检测调查：整个景观和单个野生动物保护区。在 38728 平方公里的范围内评估了景观尺度的栖息地占有情况，调查了 206 个 188 平方公里的网格单元。在 935 平方公里的班迪普尔保护区内，研究了更精细尺度的栖息地利用情况，共调查了 92 个 13 平方公里的网格单元。我们使用基于似然的栖息地占有模型分析了由此产生的豺犬踪迹数据。这些模型明确解决了在实地调查中无法检测到豺犬踪迹的问题，以及在相邻小径段上检测到的踪迹之间可能存在的空间自相关问题。我们表明，传统的“存在与不存在”分析低估了豺犬栖息地占有量 60%或 8682 平方公里[幼稚=0.27；ψL(SE)=0.68(0.08)]，在景观中。通过估计检测概率[ p(t)(L)(SE)=0.12(0.11)]来解决不完美的踪迹检测问题对于可靠的估计至关重要。在估计保护区规模的栖息地利用概率时也发生了类似的低估[幼稚=0.39；Ψs(SE)=0.71(0.06)]。在景观尺度上，主要有蹄类猎物的相对丰度主要影响了豺犬的栖息地占有量。然而，保护区内的栖息地利用主要受到人为干扰的负面影响。我们的结果是首次对多个空间尺度上的豺犬占有情况进行严格评估，具有潜在的保护价值。本研究中使用的方法具有在其他物种、景观和保护区中以具有成本效益的方式评估空间分布和栖息地利用的潜力。
