Assessing the population of grey peacock-pheasant (Polyplectron bicalcaratum) in a Southeast Asian conservation landscape
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Publication Details
Author list: Thunhikorn S., Grainger M.J., McGowan P.J., Savini T.
Publication year: 2016
Journal: Raffles bulletin of Zoology (0217-2445)
Volume number: 64
Start page: 302
End page: 312
Number of pages: 11
ISSN: 0217-2445
Languages: English-Great Britain (EN-GB)
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Abstract
The rate of biodiversity collapse in Southeast Asia is amongst the highest in the world, and averting species extinctions in the region is now a global priority. Here we estimate the density of the threatened grey peacock-pheasant (Polyplectron bicalcaratum) in the pristine sub-montane evergreen forest of Huai Kha Khaeng Wildlife Sanctuary, Western Thailand, where poaching is low. In our density assessments, we compared four commonly used survey methods: (a) triangulation using fixed listening posts; distance sampling using both (b) line transects and (c) point transects; and (d) camera trapping using the single season Royle-Nichols heterogeneity model, to assess which one is the most appropriate for population estimation in such a loud-calling terrestrial bird species. Species density was estimated between 14.69 and 22.97 birds km-2 depending on the method used. The use of auditory records to compensate for low visual detection of this cryptic species might explain the higher estimates when compared with those reported for other populations. When comparing different methods point transects and triangulation provided similar density estimates, with point transects appearing to be the most effective method due to their precision and the clear analysis protocol, while density estimates provided by triangulation depend on species specific knowledge, thereby hampering translation of detections into a population estimate. Line transects appeared to overestimate density and presented logistic difficulties in these mountainous locations, although its suitability for the survey of larger areas might render it appropriate in flat terrains. Camera trap analysis gave the widest confidence interval and suffered from complications in selecting models with realistic assumptions and delineation of the sampling area. ๏ฟฝ National University of Singapore.
Keywords
Population estimation, Triangulation
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