Ecological niche modelling reveals an elevated threat status for the Nilgiri Pipit (Anthus nilghiriensis)

Abstract

South India’s Western Ghats are a global biodiversity hotspot and an area of conservation concern with numerous endemic species. There is an urgent need for accurate threat assessments for these species, including the Nilgiri Pipit (Anthus nilghiriensis). The Nilgiri pipit is endemic to the montane grasslands of the Western Ghats, and has experienced recent rapid habitat declines. Here, we characterize the climatic niche of this species using environmental niche modelling, and use these models to estimate its range and threat status. Using the Maxent modelling algorithm and presence data from surveys by expert observers, we find that the Nilgiri Pipit is strongly sensitive to higher temperatures. We project the best-performing models to the last glacial maximum and find evidence that the species had a considerably larger range under that climatic regime. We estimate that the extent of suitable available habitat is no more than 436 km² even using the most conservative threshold. Based on this result, and the documented decline in and fragmentation of its habitat, we recommend that the species be uplisted to “endangered” on the IUCN Red List, from its current status of “vulnerable”. Finally, we compare these results to models based on identically processed eBird data, and find that eBird data produce larger estimates of suitable habitat: we, therefore, recommend caution in the interpretation of environmental niche models based on eBird data.