olfactory environment. During scheduled cleanings, it might be wise to leave at least some perches untouched until the next scheduled cleaning.

Reproduction and Development

Unlike other primates, prosimians have a primitive bicornuate uterus and, with the exception of the tarsier, have diffuse rather than hemochorial placentation. Breeding patterns vary from extremely narrow seasonal to a seasonal breeding. Gestation varies from as short as 2 months in mouse lemurs to 6 months or more in lorises, indrids, and tarsiers.

True lemurs typically have brief, distinct breeding seasons. Males might fight one another during this time. Gestation lasts 4–4.5 months. Infants develop rapidly but might nurse for 4–6 months. Most mothers carry young infants, but gentle lemurs might ''park" infants on a branch while feeding nearby. Whereas most species breed in social groups, the mongoose lemur (Eulemur mongoz) and red-bellied lemur (E. rubriventer) breed as single pairs.

Dwarf and mouse lemurs are usually found alone, but males seek out ovulating females. It is believed that males need olfactory or other contact with females to reach optimal breeding condition. Males constantly mark any clean surface during breeding, and excessive sanitation of cages interferes with breeding by the male. Females build nests where the young are born; Mirza builds a leafy nest, and the others nests in tree holes. As many as four infants can be born in a litter, but females abandon or cannibalize their young if cages are moved or cleaned while infants are in the nest. The vaginal openings of females often "seal" between estrus cycles. Gestation ranges from 2 to 3 months.

Obesity interferes with reproductive cycling in sifakas (Propithecus ) and precautions to regulate calorie availability might be necessary with these animals. Singleton births are the rule, and care should be taken to keep periparturient females in warm environments because newborns have very thin hair and chill easily. Sifakas are the only lemurs whose birth period occurs in winter in the Northern Hemisphere. Other adult females and juveniles might interfere with newborns, so it is advisable to separate periparturient females for up to a week. It is, however, desirable to maintain visual and olfactory contact with other group members. After a week, mother sifakas will not allow other group members to steal or harm their infants. Fathers might at times carry infants but should be allowed to do so only if an infant can actively rejoin its mother. Weaning of infants occurs at 3–4 months. The gestation for Propithecus is 170 days.

An aye-aye male might join a female for a few days at the time of ovulation and even sleep on or near her nest, but he otherwise remains at a distance. After a 5.5-month gestation, an infant will remain in the nest for nearly 2 months unless its mother carries it in her mouth to a new nest location.

Galagos can take 2 or 3 years to resume breeding after being moved north of the equator. Galagos are less seasonal than lorises, but the vagina in both can seal

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