Predicting current and future habitats of Adjutants under climate change for implementing strategic conservation measures in South and Southeast Asian landscapes

Abstract

The storks (Ciconiiformes: Ciconiidae) represent a captivating avian group distinguished by their heavy-wading nature, long legs, elongated necks, and robust bills. The South and Southeast Asian region boasts the most diverse population of storks, necessitating immediate conservation efforts to preserve their habitats and shield them from the escalating threats of global warming. Within the genus Leptoptilos, three distinct species exist, two of which—the Greater Adjutant (Leptoptilos dubius) and the Lesser Adjutant (Leptoptilos javanicus)—have garnered attention as threatened according to the IUCN Red List. Nevertheless, recent strides in localized conservation efforts have prompted the tagging off these imperiled species to the ‘Near-Threatened’ category, citing population upswings. However, the assessment overlooks the crucial aspects like ramifications of climatic shifts and anthropogenic-induced habitat fragmentation. Hence, this study endeavors to assess climatic impacts via an ensemble approach to species distribution modeling. The findings unveil alarming trends for both adjutants across South and Southeast Asia. The Greater Adjutant (GA) is projected to undergo a severe decline of over 95% across all future scenarios (SSP245 and SSP585 in both time periods) from its current suitable extent of 38,686 km2, which represents only 5.91% of its total extent. On the contrary, the Lesser Adjutant (LA) experiences a spatial relocation towards Southeast Asia under the SSP245 and SSP585 scenarios, resulting in a decline of over 20% from its present suitable range of 239,490 km2, which accounts 22.59% of its IUCN range. Furthermore, the resulting habitat fragmentation, propelled by climatic alterations, is severe, with the GA losing numerous viable patches entirely and the LA experiencing fragmentation in its habitat. Furthermore, given the overlapping ranges of both adjutant species, the current scenario yields a niche overlap value of 0.370. Therefore, the present study advocates for the reassessment of both GA and LA, urging their IUCN assessment under threatened category. Furthermore, strategic conservation measures are proposed in this study, involving local communities, non-governmental organizations, and governmental entities, to safeguard these remarkable avian species.