SummaryThe White-bellied Heron Ardea insignis is currently known to be restricted to Bhutan, Myanmar, and north-east India. This ‘Critically Endangered’ species is under threat from the ever-changing river systems, primarily due to anthropogenic pressures including the large number of proposed hydropower projects. We report results of the first systematic, large-scale river survey for this species in the states of Arunachal Pradesh and Assam in north-east India with the aim of establishing its evidence-based distribution and assessing the severity of threats on the river systems in the region. We conducted river surveys along all seven major river basins in Arunachal Pradesh (October 2017–March 2018) and one in Assam (January 2019) along with 200 key informant surveys from 23 localities across the region. We encountered the White-bellied Heron six times in only three of 81 sites surveyed. Three interviewees reported observing the herons in three new localities, but we did not have a direct observation of the birds in any new sites. From field observations during the river surveys as well as the interview results, we found that certain fishing methods, garbage, and sand/gravel mining could be potential reasons for restricted occurrence of the White-bellied Heron in the region. Hunting is also a threat that prevails across the region. Our study calls for governmental commitment for the protection of the species and its vulnerable ecosystem and focussed research on understanding the anthropogenic impacts on the heron.

中文翻译：

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评估印度东北部极度濒危的白腹苍鹭 Ardea insignis 的状况

摘要白腹苍鹭黄花梨目前已知仅限于不丹、缅甸和印度东北部。这种“极度濒危”物种正受到不断变化的河流系统的威胁，主要是由于人为压力，包括大量拟议的水电项目。我们报告了在印度东北部阿鲁纳恰尔邦和阿萨姆邦对该物种进行的首次系统、大规模河流调查的结果，目的是建立其基于证据的分布并评估对印度河流系统威胁的严重程度该区域。我们在阿鲁纳恰尔邦（2017 年 10 月至 2018 年 3 月）和阿萨姆邦的一个主要河流流域（2019 年 1 月）对所有七个主要河流流域进行了河流调查，并对来自该地区 23 个地区的 200 名关键知情人进行了调查。在接受调查的 81 个地点中，我们只遇到了 6 次白腹苍鹭。三位受访者报告在三个新地点观察到了苍鹭，但我们没有直接观察到任何新地点的鸟类。从河流调查期间的实地观察和访谈结果中，我们发现某些捕鱼方式、垃圾和采砂/砾石开采可能是该地区限制白腹鹭出现的潜在原因。狩猎也是该地区普遍存在的威胁。我们的研究呼吁政府承诺保护该物种及其脆弱的生态系统，并将研究重点放在了解人为对苍鹭的影响上。从河流调查期间的实地观察和访谈结果中，我们发现某些捕鱼方式、垃圾和采砂/砾石开采可能是该地区限制白腹鹭出现的潜在原因。狩猎也是该地区普遍存在的威胁。我们的研究呼吁政府承诺保护该物种及其脆弱的生态系统，并将研究重点放在了解人为对苍鹭的影响上。从河流调查期间的实地观察和访谈结果中，我们发现某些捕鱼方式、垃圾和采砂/砾石开采可能是该地区限制白腹鹭出现的潜在原因。狩猎也是该地区普遍存在的威胁。我们的研究呼吁政府承诺保护该物种及其脆弱的生态系统，并将研究重点放在了解人为对苍鹭的影响上。