From the introduction: The salsham'ai, or 'tree folk' as the humans sometimes call them, are a slender, half-high arboreal folk. They are born for life in the trees; their prehensile feet make them extremely agile climbers and all salsham'ai have a natural and instinctive ability to change their skin tones to blend in with the greens and browns of the forest. They live to about 40 human years old on average, with 50 being quite unusual.