Nesting habitat selection and challenges of conservation of the vulnerable Lesser Adjutant Leptoptilos javanicus (Horsfield, 1821) in the Chitwan National Park, Nepal

Manukala Rijal,Jagan Nath Adhikari,Bishnu Prasad Bhattarai

doi:10.2478/orhu-2021-0003

Abstract

Abstract The nesting ecology and conservation threats of the Lesser Adjutant (Leptoptilos javanicus) were studied in the Chitwan National Park, Nepal. We located nine nesting colonies during the nesting season. The number of nests was highly positively correlated with tree height, diameter at breast height and canopy cover. The uppermost canopy of the trees was the most preferred nesting place. Storks preferred to nest in compact colonies on large, widely branched trees with thin foliage cover, such as Bombax ceiba, and also nearby the foraging grounds such as wetlands and grasslands. Storks mostly preferred to nest in Bombax ceiba, but if this tree was not available, they nested in other trees, such as Shorea robusta, Ficus racemosa and Terminalia alata. During the breeding season, 180 adults, 76 nests and 88 chicks were recorded, where the highest number of chicks was recorded near the Sauraha area of the Chitwan National Park. Most of the colonies were far from human settlements, which suggest that human disturbance could be the major determinant of nesting habitat selection in this area. The wetlands nearby human settlements are either overexploited in terms of mass collection of the storks` prey species by people or disturbed highly due to presence of a large number of people. These empirical findings suggest that conservation of Lesser Adjutant mainly rely on the protection of mature Bombax ceiba trees and the reduction of human disturbance and of the collection of stork prey animals from foraging areas.

Highlights

Lesser Adjutant Leptoptilos javanicus (LA) is widely distributed in the Indian subcontinent its breeding areas are mostly restricted to smaller patches compared to its non-breeding sites
The LA is common in southern lowland Nepal, but it has been recorded in larger numbers in and around protected areas, such as Chitwan National Park (CNP), Koshi Tappu Wildlife Reserve (KTWR) and a few in the western Terai regions (Baral 2005, Poudyal & Nepal 2010, Karki & Thapa 2013, Baral et al 2020)
Understandings of nesting ecology and conservation challenges are crucial for management and conservation of threatened bird species like the LA

Summary

Introduction

Lesser Adjutant Leptoptilos javanicus (LA) is widely distributed in the Indian subcontinent (de Silva et al 2015) its breeding areas are mostly restricted to smaller patches compared to its non-breeding sites. The colonies of LA most likely occur in farmlands and swampy areas for foraging, their nests are found on trees higher than 30 m far from the foraging grounds (Karki & Thapa 2013). LA is listed globally and nationally as vulnerable (Inskipp et al 2016, BirdLife International 2017), because it has a small and declining population owing to habitat loss and degradation, hunting and disturbance (BirdLife International 2017). This species has not yet been listed as a nationally protected bird species by the National Parks and Wildlife Conservation Act of 1973 in Nepal (DNPWC 2020b). LA becomes mature for breeding around three to five years of age and pairs can be seen only during the breeding season (July–October) (Baral 2005, Sundar et al 2016, 2019)

Methods

Results

Discussion

Conclusion