A Little Cat Biology Lesson

Why are so many kittens born in the spring?

According to the many sources, female cats are “seasonally polyestrous”. That means they have multiple cycles during their breeding season, but that season can be influenced by the amount of daylight.  Since days are shorter during the Pennsylvania winter, females are less likely to go into heat from November until late January.  Then they will cycle every 1-2 weeks until a cat gets pregnant. The gestation period for kittens is about 63 day so the first kittens will arrive in late March.  Litters on average consist of 4-6 kittens. A female cat can go back into heat as early as 2 weeks after giving birth and can have 2-3 litters a year!

Unfortunately, artificial light can lessen the impact of the seasonal cycle, especially for colonies in well-lit areas like parking lots. Heat cycles of unspayed Indoor cats are also not usually affected by diminishing daylight.  Thus, “Kitten Season” never truly ends.

Why do some litters have kittens that don’t look alike?

Cats are induced ovulators, which means they need to mate to be able to release eggs from their ovaries. It can take three to four mating sessions within a 24-hour window for them to ovulate. During this period, they may mate with multiple tomcats and it’s possible for a single litter of kittens to have multiple fathers.

What are the characteristics of a female cat in heat?

Signs often include yowling and other unusual behaviors such as rubbing against things, raising their rear end in the air, spraying, and exhibiting the desire to go outside and find a mate. Sometimes females can appear more loving and other times females can be more aggressive during this cycle. Spaying a cat will eliminate these behaviors. Female kittens can reach sexual maturity as early as 4 months old.  There are no health benefits to allowing a cat to have a litter before spaying. In fact, spaying eliminates the possibility of developing uterine or ovarian cancer and greatly reduces the chance of developing mammary cancer. Spaying also prevents pyometra which is a uterine infection that if fatal if untreated.

Neutering a male cat also has benefits. Male cats will decrease or stop spraying and fight less, resulting in fewer bite and scratch wounds and lessening the spread of FIV and FeLV. They also tend to become calmer/friendlier and stay closer to home, no longer wandering looking for a female in heat.  The risk of testicular cancer is eliminated, and chance of prostate disease decreases.

If you need help with a colony you are feeding, there are many TNR groups like us to help. If cost is an issue, Low-Cost Spay/Neuter Clinics are available. Check our resource page.