so do requirements for housing and living space. There are agile leapers and slow climbers, predominantly arboreal and mainly terrestrial prosimians. There are insectivores, highly specialized leaf-eaters, bamboo-eaters, fruit-eaters, and omnivores. Some species occupy tree holes or build nests that are used as general sleeping quarters or primarily for the care of infants. Some prosimians give birth to twins or small litters, whereas the norm for most species is a single offspring. Some prosimians resemble bats in having ultrasonic calls, and some species have very complex vocal repertoires. A few species even exhibit periods of torpor resembling hibernation. Almost every prosimian species has its own distinctive life style. Some live in large groups, others in small groups; some travel alone, some in pairs. Most prosimians scent-mark and urine-mark their surroundings, others also mark with feces. There might be a greater diversity of scent glands on various body parts in prosimians than in any other mammal, and the ability to maintain scent marks in their environment appears to be important for the general well-being of prosimians.
Despite the enormous diversity of prosimians, a few general comparisons between prosimians and other primates can be made. Prosimians are less inquisitive, less restive, and less destructive to their environment than other primates; the only exception is the aye-aye, which will gnaw through structures. Prosimians are the primates farthest removed from humans, and there is much less likelihood of disease transmission between humans and prosimians than between humans and other primates. In fact, no case of a transmission of a zoonosis from prosimian to human could be found in a search of the literature.
In contrast with other primates, which (with the single exception of the night monkey, Aotus) are diurnal, prosimians are primarily nocturnal. Only among the lemurs are there some diurnal forms. Some are also crepuscular (active only at dawn and dusk), a few are cathemeral (being sporadically active throughout the 24-hour cycle), and a few display some flexibility in circadian rhythms. The captive maintenance of prosimians must take these patterns into account. Some institutions might wish to maintain reverse light cycles by using regular room lighting at night and low levels of red illumination during the day so that caregivers can observe them during their active period.
The Duke University Primate Center has had the most comprehensive experience in the care of prosimians of any institution in the United States and is the largest captive prosimian colony in the world (Bennett and others 1995). The committee's recommendations are based largely on successful experiences at Duke.
Prosimians can be kept safely in a wide variety of cages and enclosures, ranging from multihectare outdoor habitat enclosures, corrals, and large indoor