Elevation and landscape change drive the distribution of a montane, endemic grassland bird

Abstract

Context Tropical montane habitats support high biodiversity and are hotspots of endemism, with grasslands being integral components of many such landscapes. The montane grasslands of the Western Ghats have seen extensive land‐use change over anthropogenic timescales. The factors influencing the ability of grassland‐dependent species to persist in habitats experiencing loss and fragmentation, particularly in montane grasslands, are poorly known. Objectives We studied the relationship between the Nilgiri pipit Anthus nilghiriensis , a threatened endemic bird that typifies these montane grasslands, and its habitat, across most of its global distribution. We examined what habitat features make remnant grasslands viable, which is necessary for their effective management. Methods We conducted 663 surveys in 170 sites and used both single‐season occupancy modeling and N ‐mixture modeling to account for processes influencing detection, presence, and abundance. Results Elevation had a positive influence on species presence, patch size had a moderate positive influence, and patch isolation had a moderate negative influence. Species abundance was positively influenced by elevation and characteristics related to habitat structure, and negatively influenced by the presence of invasive woody vegetation. Conclusions The strong effect of elevation on the highly range‐restricted Nilgiri pipit is likely to make it vulnerable to climate change. This highly range‐restricted species is locally extinct at several locations, and persists at low densities in remnants of its habitat left by recent fragmentation. Our findings indicate a need to control and reverse the spread of exotic woody invasives to preserve the grasslands themselves and the specialist species dependent upon them.

Using the area of habitat to assess the extent of protection of India's birds

“…Such over‐representation of the published ranges of eight species also causes their over‐representation in our calculations of AOHs. For example, Nilgiri Pipit is found only in the montane grasslands of Nilgiri and Palani‐Annamalai Hills (Lele et al, 2020; Robin et al, 2014). Its published range also includes parts of Biligirirangana Hills, Brahmagiri and Banasura Hills in the north and Ashambu‐Agasthyamalai Hills in the south.…”

Opportunities and challenges in using remote sensing for invasive tree species management, and in the identification of restoration sites in tropical montane grasslands

“…The montane grasslands of the Western Ghats contain at least 70 threatened grass species (Matthew, 1999) with 30 of these listed as endangered (Karunakaran et al, 1998). The shola grassland also supports an endangered ungulate (Nilgiri tahr, Nilgiritragus hylocrius; (Alempath, 2008)) and a threatened bird (Nilgiri Pipit, Anthus nilghiriensis; (Lele et al;Robin et al, 2014)). Additionally, there are at least 20 frog species that are restricted to these grasslands (Abraham et al, 2015;Biju et al, 2010;Princy et al, 2017;Vijayakumar et al, 2014).…”

Opportunities and challenges in using remote sensing for identifying grassland restoration sites and invasive tree species management in a global biodiversity hotspot

“…The montane grasslands of the Western Ghats contain at least 70 threatened grass species (Matthew, 1999) with 30 of these listed as endangered (Karunakaran et al, 1998). The shola grassland also supports an endangered ungulate (Nilgiri tahr, Nilgiritragus hylocrius; (Alempath, 2008)) and a threatened bird (Nilgiri Pipit, Anthus nilghiriensis; (Lele et al;Robin et al, 2014)). Additionally, there are at least 20 frog species that are restricted to these grasslands (Abraham et al, 2015;Biju et al, 2010;Princy et al, 2017;Vijayakumar et al, 2014).…”