By Jennifer Copley (Last Updated 12 May 2011)
The ability to produce a litter of kittens fathered by more than one tom cat is called superfecundation. A female cat in heat attracts many different males. If she has a particular preference, she will only mate with one tom, waiting for him to recover after prior matings rather than seeking the attentions of other males while he is incapacitated. But many female cats will accommodate a broader circle of admirers, so their ova may be fertilized by the sperm of various males. The result is a diverse litter of kittens that look very different from one another. Superfecundation is particularly likely to occur in urban and suburban areas where cats have higher population densities, which increases the number of male respondents to the call of a female cat in heat.
In addition to the potential for superfecundation, some female cats will actually go into heat and be impregnated while already pregnant, a phenomenon known as superfetation. In this case, a mother cat may simultaneously carry two litters at different stages of development. The less developed litter may be born prematurely along with the more advanced litter, which usually results in death for the premature kittens, but if they’re lucky, they manage to hang on for the full term and are born 2-6 weeks later. This places a significant burden on the nursing mother, because she suddenly has a lot of kittens to cope with all at once, though many cats manage to deal effectively with these large, staggered litters.
See the Pregnant Cats and Kittens Page for information on caring for pregnant cats, kitten development week by week, kitten training, kitten care, and more. For a full list of cat articles, see the main Cats page.
Reference: Morris, D. (1987). Catlore. London, UK: Jonathan Cape Ltd.