Baseline data on intrinsic–extrinsic determinants of spatial distribution of flagship species helps wildlife managers develop their management strategies. Globally, large herbivores are in range contraction due to the expansion of human habitation. Of late, alien invasion is raising management concerns due to its detrimental effect on native biota. This study evaluating the determinants of spatial detectability and density distribution of blackbuck Antilope cervicapra, an endemic species of the Indian subcontinent, demonstrates the negative influence of Prosopis juliflora, an alien invasive, on the native blackbuck at three reserves—Point Calimere Wildlife Sanctuary, Guindy National Park and Sathyamangalam Tiger Reserve, Tamil Nadu, India. Using distance sampling technique, the study has surveyed blackbuck from 26 grid-based, spatially replicated line-transects between January 2018 and July 2019. Furthermore, 27 covariates related to climate, habitat and anthropogenic pressure were evaluated to determine their effect on spatial detectability and density distribution. Regression by Empirical Variable Selection showed that blackbuck spatial detectability and density distribution increase significantly with the extent of grassland, habitat openness and grass biomass, but decreases with Prosopis cover, shrub cover, percentage of woodland and distance to water, thus revealing their negative effect on the blackbuck. Besides, the Prosopis cover also decreases significantly the key positive predictors of the density distribution of blackbuck, namely the extent of grassland, habitat openness and grass productivity. Thus, the study concludes that the alien invasive species has a negative effect on the native blackbuck population. This raises the need for controlling or eliminating the invasive species in order to conserve, in the long run, the endemic blackbuck at the three reserves.

有关旗舰物种空间分布的内在决定因素和外在决定因素的基准数据可帮助野生动植物管理者制定其管理策略。在全球范围内，大型食草动物由于人类栖息地的扩大而范围缩小。最近，外来入侵由于其对原生生物群的有害影响而引起管理关注。这项研究评估了印度次大陆的一种特有种Blackbuck Antilope cervicapra的空间可检测性和密度分布的决定因素，证明了Prosopis juliflora的负面影响，是外来入侵者，在三个保护区（印度Calimil野生动物保护区，Guindy国家公园和印度泰米尔纳德邦的Sathyamangalam老虎保护区）的Blackbuck上。该研究使用距离采样技术，调查了2018年1月至2019年7月之间26个基于网格，空间复制的线样的Blackbuck。此外，还评估了与气候，栖息地和人为压力相关的27个协变量，以确定它们对空间可探测性和密度分布。经验变量选择的回归表明，黑草的空间可检测性和密度分布随草地的范围，生境的开放性和草木生物量的增加而显着增加，而随Prosopis的减少而降低覆盖率，灌木覆盖率，林地百分比和距水的距离，从而揭示了它们对blackbuck的负面影响。此外，Prosopis的覆盖率也显着降低了Blackbuck密度分布的关键正向预测指标，即草地的面积，栖息地的开放度和草的生产力。因此，研究得出的结论是，外来入侵物种对本地黑black种群具有负面影响。从长远来看，这就需要控制或消除入侵物种，以便长期保存这三个保护区的地方黑black。