Rangelands and crop fallows can supplement but not replace protected grasslands in sustaining Thar Desert's avifauna during the dry season

Abstract

1. The Indian Thar Desert has lost much of its grasslands over the last few decades, mainly due to land-use change from pastoralism to agriculture. Expanding croplands and intensifying grazing pressures are popularly hypothesized to be the major drivers of biodiversity loss in the region. Our study aims to investigate the effects of contemporary land-use change on bird communities of the Western Thar Desert.2. We surveyed 59 randomly laid line transects in a ~2000 sq.km study area, to quantify parameters of bird community structure in three predominant land-cover types viz. protected grasslands, rangelands, and fallow croplands. Fieldwork for the study was conducted in the dry season (winter and summer) between December 2018 and April 2019.3. During winter, overall bird species richness and abundance was highest in protected grasslands followed by fallow croplands and rangelands. Protected grasslands also had a higher abundance of diet and habitat specialists. Compared to protected grasslands, density was lower in fallow croplands and rangelands for 35% and 10% of species, respectively. A majority of the negatively affected species were insectivorous grassland specialists.4. Contrary to the pattern in winter, overall bird species richness, abundance, composition, and guild structure in summer was similar across the three land-use types. Only one of the 17 analysed species had significantly lower density in modified land-use types.5. Overall, protected grasslands were the best habitat for birds and specifically important for diet and habitat specialists, more so during the winter. Rangelands and fallow croplands sustained most generalists at comparable densities but had severe negative impacts on specialist species.6. Synthesis and application: Our results point out that low-intensity agro-pastoral land-uses can supplement, but not replace, protected areas in conservation of Thar Desert's avifaunal diversity. This is in consonance with the idea of managing dryland habitats as agro-grassland mosaics with embedded protected areas, in order to reconcile human needs and biodiversity conservation at a landscape scale.