Litter (zoology)

Puppy litter at 8 weeks old

Alitteris the live birth of multipleoffspringat one time inanimalsfrom the same mother and usually from one set ofparents,particularly from three to eight offspring. The word is most often used for the offspring ofmammals,but can be used for any animal that gives birth to multiple young. In comparison, a group ofeggsand the offspring that hatch from them are frequently called aclutch,while young birds are often called abrood.Animals from the same litter are referred to as littermates.

Litter

A species' average litter size is generally equal to one half of the number ofteatsand the maximum litter size generally matches the number of teats. Not all species abide by this rule, however. Thenaked mole rat,for example, averages roughly eleven young per birth and has eleven teats.

Animals frequently display grouping behavior inherds,swarms,flocks,orcolonies,and these multiple births derive similar advantages. A litter offers some protection frompredation,not particularly to the individual young but to the parents' investment in breeding. With multiple young, predators could eat several and others could still survive to reach maturity, but with only one offspring, its loss could mean a wasted breeding season. The other significant advantage is the chance for the healthiest young animals to be favored from a group. Rather than it being a conscious decision on the part of the parents, the fittest and strongest baby competes most successfully for food and space, leaving the weakest young, orrunts,to die through lack of care.

In the wild, only a small percentage, if any, of the litter may survive to maturity, whereas for domesticated animals and those in captivity with human care the whole litter almost always survives.Kittensandpuppiesare in this group.Carnivorans,rodents,andpigsusually have litters, while primates and larger herbivores usually have singletons.