Lesser Adjutant Leptoptilos javanicus Horsfield, 1821 (Ciconiiformes: Ciconiidae) in the dry lowlands of Sri Lanka: distribution, ecology, and threats

Abstract

The Lesser Adjutant Leptoptilos javanicus is a globally threatened species of stork; in Sri Lanka, it is a scarce resident breeder, and the largest bird in the country, yet the population status and ecology of the species is poorly understood.  This study tracks the stork’s spatial distribution and habitat use within the island, along with aspects of its ecology.  Data was collected via field sampling and questionnaire surveys, over a period of five years across the lowlands of the country.  The bird was observed 184 times, with numbers per sighting ranging from 1–17 individuals.  The species’ distribution was restricted to dry lowlands (rainfall <2200mm, elevation <300m).  The bird showed preference for savannah/woody savannahs, dry mixed evergreen forests, permanent wetlands, and croplands, and was prominently found within protected areas.  Lesser Adjutants were generally solitary, except in the driest months of the year (i.e., August–September and March–April), which are probably the two breeding periods of the bird in Sri Lanka.  Except for an abandoned nest, no active nest was found.  Habitat loss and fragmentation, hunting pressure, agricultural intensification, and development projects were identified as potential threats faced by the species, which varied in magnitude across the country.