Rats can reproduce rapidly, with each adult female producing an estimated average of 40 offspring annually when conditions are ideal.
Rats have an exceptionally high reproductive output that can present problems if your home becomes overrun with rats, leading to an infestation that quickly spirals out of control if action is not taken immediately.
Rats are polygynandrous
Rats are polygynandrous, meaning they mate with multiple males to increase genetic diversity and decrease the chances of unfertilized eggs. Rats use this strategy in order to increase reproductive success.
Female rats will typically ovulate every four to six days, releasing some mature eggs into her ovaries. When she goes “on heat”, signs may include ear wiggling, back arching and intense vibrating of her body during mating dance (matting dance = excessive vibrating of body parts).
Monogamous rats typically pair for only one breeding season. Thus, monogamous species of rodents have lower rates of fertility.
Orians’ polygyny threshold model proposes that females choose polygyny when they see males who offer superior resources for her offspring, creating resourced-based polygyny where males compete to obtain territories with these resources.
They mate with multiple males
Rats can produce up to 2000 offspring annually if left unchecked, according to Rentokil’s interactive project that visualizes this fact and warns of their rapid reproductive rate, warning against how quickly their numbers could spiral out of control if unchecked.
Female rats typically reach sexual maturity at four months old while male rats usually do at three to six months. Male rats mark their territory during mating season by excreting tiny drops of urine that contain lipocaliene molecules – this sticky molecule helps establish territorial claims on its territory.
Female rats that are in heat will demonstrate various behavioral cues to signal to male rats they are ready for mating, including opening their vagina to gape, their ears vibrating slightly and arching their back.
Female rats typically give birth to anywhere from five to ten pups at once in one or two hour cycles, usually without complications or missteps during labor.
They have a high rate of fecundity
Rats can produce over half a billion offspring in just three years if given enough food and shelter, an alarming statistic which could spell disaster in your home if there is an infestation of rats.
Understanding rat reproduction is crucial to effective control. By decreasing their resources needed for breeding, you can halt their reproduction and prevent an infestation from becoming out-of-hand.
Female rats reach sexual maturity ready for reproduction as soon as their estrous cycle has completed its four phases – proestrus, estrus, metestrus and diestrus – with ovulation occurring near the end of metestrus.
They can re-conceive immediately after giving birth
Rats are polygynandrous, meaning they mate with multiple male rats at once. After giving birth, female rats can often reconceive within 48 hours after giving birth – an ability known as polygynandrous mating.
Female rats in labor may hunch or squeak during contractions. She may try to clean herself as the time of birth approaches; this can be stressful, so make sure she has somewhere safe to give birth.
An aquarium or large plastic bin makes a suitable birthing chamber and early nursery, provided there are no bars or surfaces where babies could become stuck and potentially suffocate.