Community structure and habitat associations of lowland grassland birds in Nepal

Abstract

Somee of the remaining examples of Asian tall grasslands are found in lowland Nepal. They support aa rich, threatened fauna and are an important subsistence resource for local people. The grasslands aree cut and burned annually by local people and by staff of the protected areas. Little is understood off the implications of these practices for the grassland fauna. This thesis examines the avian diversity,, community structure and habitat associations of grassland bird species for their managementt and conservation. Whatt people call lowland grasslands, is in fact, an assemblage of diverse habitat types in itself. Spatio-temporall variations in bird communities are assessed with reference to different grassland types.. Royal Chitwan National Park and Sukila Phanta Wildlife Reserve both differ in the bird communitiess they contain. While the former possesses species that prefer tall moist grasslands at forestt edges, the latter shows bird communities that prefer short open grasslands away from forests. Grasslandd avifauna is largely dominated by sedentary resident species. Insectivorous birds are the mostt numerous of all forming the largest guild group. Most threatened species are breeding residents andd grassland specialists. The community is dominated by a large number of generalists and relativelyy few obligate grassland birds. Commonn Stonechat Saxicola torquata, Pied Bushchat S. caprata, Black Francolin Francolinus francolinusfrancolinus and several other species are found in grassland-like habitats showing thei nature.. Saxicola torquata was the most frequently observed bird species. Among the specialists, Striatedd Grassbird Megalurus palustris and Jerdon's Bushchat Saxicola jerdoni are associated with wett grasslands whereas Bengal Florican Houbaropsis bengalensis, Hodgson's Bushchat Saxicola insignisinsignis and Bright-headed Cisticola Cisticola exilis are associated with Imperata grasslands. Swamp Francolinn Francolinus gularis, Chestnut-capped Babbler Timalia pileata and Yellow-bellied Prinia PriniaPrinia flaviventris are found in tall moist grasslands such as Narenga, Saccharum and Phragmites. White-tailedd Stonechat Saxicola leucura prefers early successional Saccharum grasslands, whilst Grey-crownedd Prinia Prinia cinereocapilla and Pale-footed Bush-warbler Cettia pallidipes are partial too Themeda grasslands that grow on well-developed soils close to sal or mixed forests. Slender-billed Babblerr Turdoides longirostris, a bird restricted to Chitwan grasslands, is associated with Narenga orr Imperata-Narenga grasslands. Bristled Grassbird Chaetornis striatus is mainly found in Imperata andd Saccharum grasslands. Rufous-rumped Grassbird Graminicola bengalensis, a strict specialist of densee tall grasslands, is found in all grassland types, though it shows preference for moister grasslands. . Grasslandss are affected by several management regimes for example, fire, grazing, cutting etc. The rolee of fire is controversial and its long-term effect is not known at this stage. In tall moist grasslands,, it creates a mosaic of habitat that shows increased diversity and abundance, while in shortt dry grassland and those growing at forest edges it contributes to reduced diversity. The immediatee effect of cutting, ploughing and flooding in grasslands is reduced avian species richness. Heavyy cattle grazing is detrimental to many grassland specialists that prefer tall grasslands. The remainingg grasslands in Nepal are in a rapid successional phase, either towards hardier coarse grass speciess or towards forests that grow at the edge of grasslands. Additionally many of the grasslands aree deteriorating and are in degraded conditions as wildlife habitat. These fragmented and degraded grasslandss need urgent management steps for the conservation of declining grassland fauna and especiallyy for birds that have habitat requirements more at micro-level than larger fauna.