Task: Question Answering
Input (English): Passage: The birds lived in forests at both montane and lowland elevations – they are thought to have moved seasonally, living at higher elevation in summer and descending to lower elevation in winter. Huia were omnivorous and ate adult insects, grubs and spiders, as well as the fruits of a small number of native plants. Males and females used their beaks to feed in different ways: the male used his bill to chisel away at rotting wood, while the female's longer, more flexible bill was able to probe deeper areas. Even though the huia is frequently mentioned in biology and ornithology textbooks because of this striking dimorphism, not much is known about its biology; it was little studied before it was driven to extinction.
The huia is one of New Zealand's best-known extinct birds because of its bill shape, its sheer beauty and special place in Māori culture and oral tradition. The bird was regarded by Māori as tapu (sacred), and the wearing of its skin or feathers was reserved for people of high status. 
Question: What are thought to have moved seasonally, living at higher elevations in summer?
Output (English): Huia.