Reproductive biology

Mating behavior varies according to whether the male and female of a sengi species are monogamous (for life) or solitary. Males of solitary species, or young males of monogamous species on their first mating run, go in search of rutting females of their particular species by sensing olfactory cues left in scent markings left by females in strategic spots. When a male and female of a solitary species have found each other, they stay together for several days, mate, then go their separate ways. Pair-bonded couples remain together as long as both are alive. They may be strictly monogamous or they may mate with other individuals while always reassuming the original pair relationship. Males take little or no part in direct care of the young.

A female sengi carries four or six mammae, depending on species.

The reproductive systems of female sengis, during mating, show polyovulation, in which anywhere from a dozen to 100 egg cells are released during ovulation, most of which become

The checkered sengi (Rhynchocyon cirnei) foraging in southeast Africa. (Photo by Tom McHugh/Photo Researchers, Inc. Reproduced by permission.)

fertilized by male sperm and begin cell division, but only one, two, or three fertilized eggs will implant in the uterus, while the rest are expelled. This may be a holdover from past ages when sengi ancestors bore larger litters, as do most mammal species in their size range.

After a gestation period of about 50 days, sengis are born in small litters of one, two, or rarely, three or four young, which enter the world precocial, i.e., with their eyes open, full coats of fur, and able to move about and explore within a few days, often a few hours, of birth. The mother leaves the infants alone most of the time, in a shelter separate from the parents' shelter, coming by only to nurse at fixed intervals, a behavior known as absentee parental care. After five days the mother starts feeding the young mashed insects that she stuffs in her cheek pouches, in addition to her milk.

In about two weeks, the young emerge from their shelter, effectively weaned and able to forage, although they will remain with the mother for three or four weeks, accompanying her as she forages. Eventually, within a month to two months after weaning, the young strike off on their own, or are driven from the territory by the parents, to establish territory of their own, reaching sexual maturity by 40-50 days. A female sengi may produce several litters per year.

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