slopes, between 800 and 1,600 meters elevation. Above 2000 meters the sclerophyll forests transition to the high-elevation ericoid thickets, which are considered a distinct subalpine ecoregion. Fauna Endemic species include a number of birds, reptiles and mammals including the Alaotra gentle lemur (Hapalemur alaotrensis) and a number of shrews, tenrecs, and rodents. The subhumid forests were formerly home to the island's distinct megafauna, including giant lemurs, some of them larger than modern gorillas, the elephant birds (Aepyornithidae), and giant tortoises. The Sambirano mouse lemur (Microcebus sambiranensis), Sambirano woolly lemur (Avahi unicolor), and Sambirano fork-marked lemur (Phaner parienti) are endemic to the Sambirano region. The ecoregion is home to several endemic and limited-range species of birds. The rufous-headed ground roller (Atelornis crossleyi), grey-crowned tetraka (Xanthomixis cinereiceps) and forest rock thrush (Monticola sharpei) are largely endemic to the ecoregion. The yellow-bellied sunbird-asity (Neodrepanis hypoxantha), Madagascar yellowbrow (Crossleyia xanthophrys), and cryptic warbler (Cryptosylvicola randrianasoloi) are native to the subhumid forests and to the higher-elevation ericoid thickets. The Madagascar serpent eagle (Eutriorchis astur), short-legged ground roller (Brachypteracias leptosomus), Madagascar red owl (Tyto soumagnei), and Pollen's vanga (Xenopirostris polleni) live in both the subhumid forests and the lowland moist forests. The brown emu-tail (Bradypterus brunneus) lives in the lowland and subhumid forests and the ericoid thickets. Lake Alaotra and its wetlands were once home to two endemic water birds, the Madagascar pochard (Aythya innotata) and Alaotra grebe (Tachybaptus rufolavatus). Both have disappeared from the lake. The Alaotra grebe is thought extinct, and the Madagascar pochard was thought extinct until a small population was sighted at Lake Matsaborimena. Two dry forest species, Coquerel's coua (Coua coquereli) and Schlegel's asity (Philepitta schlegeli) also inhabit the humid forests of Sambirano. Threats and conservation The central highlands are the most densely populated region of Madagascar, and includes the country's capital and largest city, Antananarivo. The highlands' population is growing. Madagascar's high plateau forests have been altered by humans in most places. There has been extensive slash-and-burn activity by native peoples in the central highlands, eliminating most forest. Other impacts include land clearing for agriculture, overexploitation, introduced species, and pollution. 7.68% of the ecoregion is in protected areas. Protected areas include: Marojejy National Park Isalo National Park Ranomafana National Park Andohahela National Park Andringitra National Park Lokobe National Park Montagne d'Ambre National Park Befotaka Midongy National Park Tsaratanana Strict Nature Reserve Ambatovaky Special Reserve Ambohijanahary Special Reserve Ambohitantely Special Reserve