Amity Institute of Forestry and Wildlife, Amity University, Noida, Uttar Pradesh, India.
Conservation Genome Resource Bank for Korean Wildlife (CGRB), Research Institute for Veterinary Science and College of Veterinary Medicine, Seoul National University, Seoul, Republic of Korea.
PLoS One. 2021 Dec 8;16(12):e0259805. doi: 10.1371/journal.pone.0259805. eCollection 2021.
Diurnal raptors show a wider distribution compared to other groups of birds including passerines, woodpeckers, and seriemas, but occur at lower-than-expected densities. Estimating the precise abundance is essential to achieve conservation goals but the methods used to estimate the populations of birds need to be appropriate to arrive at meaningful conclusions. We compared the two survey methods: roadside point count and strip transects, for estimating species richness and abundance of raptors in the arid landscape of Rajasthan. Roadside point counts and roadside strip transects were done on 50 transects between December 2019- February 2020 (with an average length of 20 km and a total distance of 3000 km) to assess the species richness and abundance of raptors. A total of 2954 observations of raptors belonging to 35 species were recorded using both methods. Mann Whitney U test result showed no significant difference in species richness and abundance estimates between both methods (p = 0.206). The point count method yielded a higher relative abundance of 2.79 individuals [10 km2]-1h-1 than the 1.90 individuals [10 km2]-1h-1 obtained during the strip transect. Also, the number of unidentified species were less for point counts. Extrapolation values indicated that both the methods do not differ much for the detection of unsampled species. The choice of survey method depends on the objectives of the study, but our results favor the use of point counts rather than strip transects to survey raptors in open habitats. The information generated from this study is expected to provide the most efficient method to study the abundance and distribution of raptors in similar landscapes.
与雀形目鸟类、啄木鸟和蛇鹫等其他鸟类群相比，日行性猛禽的分布范围更广，但它们的密度却低于预期。估计准确的丰度对于实现保护目标至关重要，但用于估计鸟类种群的方法需要适当，才能得出有意义的结论。我们比较了两种调查方法：路边点计数法和样带法，以估计拉贾斯坦邦干旱景观中猛禽的物种丰富度和数量。2019 年 12 月至 2020 年 2 月期间，在 50 条样带上进行了路边点计数法和路边样带法的调查（每条样带平均长度为 20 公里，总距离为 3000 公里），以评估猛禽的物种丰富度和数量。使用这两种方法共记录了 35 种猛禽的 2954 次观察结果。曼-惠特尼 U 检验结果显示，两种方法的物种丰富度和数量估计值没有显著差异（p=0.206）。点计数法的相对丰度为 2.79 只[10 公里 2] -1 h -1，高于样带法的 1.90 只[10 公里 2] -1 h -1。此外，点计数法记录的未识别物种数量较少。外推值表明，这两种方法对于检测未采样的物种差异不大。调查方法的选择取决于研究的目的，但我们的结果倾向于使用点计数法而不是样带法来调查开阔生境中的猛禽。本研究产生的信息有望为研究类似景观中猛禽的数量和分布提供最有效的方法。
