In a state with a per capita GDP of roughly £820 ($1,120) a year, reviving Manas has cost IFAW an estimated $2.5m (£1.9m) so far. Menon says it has been worth it. As "mega-herbivores", rhinos indicate the health of the Manas grasslands: their presence suggests the habitat is in good ecological condition, providing water, clean air and carbon sequestration. Grassland regeneration has also helped conserve species like the endangered pygmy hog and the world"s rarest bustard, the Bengal florican.