SummaryWhite-bellied Heron Ardea insignis (WBH) is critically endangered, but we lack data on many aspects of its basic ecology and threats to the species are not clearly understood. The goal of this study was to analyse WBH foraging microhabitat selection, foraging behaviour, and prey preferences in two river basins (Punatsangchhu and Mangdechhu) in Bhutan which are likely home to one of the largest remaining populations of WBH. We also explored the relationship between the relative abundance of the WBH and prey biomass catch per unit effort within four foraging river microhabitats (pool, pond, riffle and run). Prey species were sampled in 13 different 100-m thalweg lengths of the rivers using cast nets and electrofishing gear. Riffles and pools were the most commonly used microhabitats; relative abundance was the highest in riffles. The relative abundance of WBH and prey biomass catch per unit effort (CPUE) also showed a weak but significant positive correlation (rs = 0.22). The highest biomass CPUE was observed in riffles while the lowest was found in the ponds. From the 97 prey items caught by the WBH, 95% of the prey were fish. The WBH mainly exploited three genera of fish (Garra, Salmo, and Schizothorax) of which Schizothorax (64%) was the most frequently consumed. This study provides evidence in support of further protection of critical riverine habitat and fish resources for this heron. Regular monitoring of sand and gravel mining, curbing illegal fishing, habitat restoration/mitigation, and developing sustainable alternatives for local people should be urgently implemented by the government and other relevant agencies. Further study is also required for understanding the seasonal variation and abundance of its prey species in their prime habitats along the Punatsangchhu and Mangdechhu basins.

中文翻译：

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影响不丹白腹苍鹭 (Hume, 1878) 觅食活动的生态和环境因素

摘要白腹苍鹭黄花梨(WBH) 极度濒危，但我们缺乏关于其基本生态学许多方面的数据，并且对该物种的威胁尚不清楚。本研究的目的是分析不丹两个河流流域（Punatsangchhu 和 Mangdechhu）的 WBH 觅食微生境选择、觅食行为和猎物偏好，这两个流域可能是剩余最大的 WBH 种群之一。我们还探讨了在四个觅食河流微生境（水池、池塘、浅滩和奔跑）内，WBH 的相对丰度与单位努力的猎物生物量捕获量之间的关系。使用投网和电钓设备在 13 个不同的 100 米 thalweg 长度的河流中对猎物物种进行采样。浅滩和水池是最常用的微生境；相对丰度在浅滩中最高。s= 0.22)。在浅滩中观察到最高的生物量 CPUE，而在池塘中发现最低的 CPUE。在 WBH 捕获的 97 个猎物中，95% 的猎物是鱼。WBH主要开发了三属鱼（加拉,鲑鱼， 和裂胸） 其中裂胸(64%) 是最常食用的。这项研究为进一步保护这只苍鹭的重要河流栖息地和鱼类资源提供了证据。政府和其他相关机构应紧急实施对砂石开采的定期监测、遏制非法捕捞、栖息地恢复/缓解以及为当地人民开发可持续的替代方案。还需要进一步研究以了解其猎物物种在 Punatsangchhu 和 Mangdechhu 盆地沿线主要栖息地的季节性变化和丰富度。