Is the population of the Critically Endangered White-bellied Heron in Namdapha Tiger Reserve, India, declining?

Abstract

The Critically Endangered White-bellied Heron Ardea insignis is a large-bodied, range-restricted, piscivorous bird found in the Himalayan mountains. With fewer than 60 individuals remaining globally, regular monitoring efforts are required to understand the conservation status of this rare species better. Here, we present the results of river surveys from 2017 and 2023-24 for the White-bellied Heron in an important protected area, the Namdapha Tiger Reserve, in Arunachal Pradesh. The encounter rate in 2017 was 0.55 herons per km, however; we did not detect the bird during intensive river sampling in the same stretches in 2023-24. This area within the reserve was once a stronghold for the species and they currently appear to be declining or locally extinct. Given the declines within this Protected Area, the drivers for the same need to be determined. While repeated monitoring of rivers has helped reveal this decline, locating and conserving stretches of river utilised by the remaining individuals away from the core zone is now critical. [Supplementary material for this article can be found at https://doi.org/xxx]