Assessing the Status of the Critically Endangered White-bellied HeronArdea insignisin north-east India

Abstract

<jats:title>Summary</jats:title> <jats:p>The White-bellied Heron <jats:italic>Ardea insignis</jats:italic> 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.</jats:p>

Drivers of Taxonomic, Phylogenetic, and Functional Beta Diversity of Himalayan Riverine Birds

“…Elevation is an important driver of riverine bird diversity (Manel et al, 2000). Interestingly, at elevations above 300 m in the E Himalaya, the beta diversity patterns were consistent and showed a relatively lower species turnover at elevations below 300 m. In the E Himalaya, the lowermost elevations are characterized by higher anthropogenic disturbances, resulting threats such as lower forest cover, and boulder and sand mining (Srivastava et al, 2002;Menzies et al, 2021), which likely contribute to the lower species turnover in the lowland elevations. Anthropogenic activities negatively impact specialist bird species resulting in the persistence of generalist species that are able to withstand habitat changes (Sinha et al, 2019a) likely resulting in lower turnover in the more modified, low elevation riparian habitats.…”

“…It has high biodiversity value as recognized by its four biodiversity hotspots, 60 ecoregions and 330 important bird areas (Myers et al, 2000). Riverine areas in the Himalaya harbor the highest diversity of specialist riverine birds in the world, among which several species are of conservation concern (Buckton, 1998;Sinha et al, 2019a;Menzies et al, 2021).…”

“…All species' nomenclature follows the Clements Checklist by the Cornell Lab of Ornithology (Clements, 2007). For more details on the field survey design, please see Menzies et al (2021) for the E Himalaya and Sinha et al (2019a) for the W Himalaya.…”

“…The differences in species richness and environment offer an excellent opportunity to determine the role of environmental filtering (vis-à-vis other factors) in driving beta diversity patterns. While studies in the W and Central Himalaya have examined species-habitat relationships (Manel et al, 1999;Buckton and Ormerod, 2008;Sinha et al, 2019a,b), studies from the E Himalaya remain restricted to few studies providing species-specific information (Menzies et al, 2021). Hence, our understanding of the drivers of regional community composition and beta diversity patterns of river bird assemblages remains limited (Manel et al, 2000;Buckton and Ormerod, 2008).…”

Ecological and environmental factors affecting the foraging activity of the White-bellied Heron Ardea insignis (Hume, 1878) in Bhutan

“…Apart from dams and exposed power lines, we have also encountered numerous locations where dredging of sand and gravel from the riverbanks is carried out for commercial as well household consumption in our study area. Uncontrolled sand and gravel mining in the river systems is a serious threat not only to globally threatened species (Menzies et al 2020) but also native fish and biotic communities (Kanehl andLyons 1992, Koehnken et al 2020). Also, construction of access roads and storage sites for sand mining leads to further fragmentation and loss of the riverine vegetation (Kondolf et al 2007, Kumar andKumar, 2014), which is crucial for the nesting and roosting of WBH (Khandu et al 2020a(Khandu et al , 2020b.…”