Do Rats Eat Their Babies?
Yes in many of the species of rats it has been seen that the mother rat kills and eats their own babies. This phenomenon is termed Cannibalism in Rats. Rats commonly eat their babies and this situation occurs primarily due to the various maternal stress-related symptoms, disturbance around parturition, problems with humidity regulation, or due to the various other disturbances in the rat colony as a result of various environmental pressures.
Now it is also to be noted that all mother rats of the same colony or species will not always eat their babies.
Only under certain conditions of stress and confusion, there will be some mother rats that may get confused due to their various behavioural patterns leading them to kill their own babies.
It has been also reported that when the mother is hungry or devoid of sufficient nutrients during her time of pregnancy then chances are very high that she may give birth to unhealthy or deformed pups.
During such a case if an unhealthy deformed pup is born then the mother may opt to typically kill and consume it. rather than nursing it under stress.
Many researchers believe that various rat species like many of the other rodents due to their complex behaviour pattern are often seen to ignore, kill, and even feed on their newly born pups (babies). The primary reason for this is an interruption or disturbance of mothering behaviour.
Many researchers believe that such a disturbance of mothering behaviour is mostly due to Postpartum Depression, during which a rapid drop in the hormones of the mother occurs which leads to various unconditional physical, emotional, and behavioral changes just after giving birth or within 14 days or so after giving birth.
So, Postpartum Depression (PPD) leading to a disturbance around parturition is also one of the major reasons leading to the killing of the pups and eating them by their mom.
Some mothers may also think that there’s no sense in spending energy or resources which is very limited in their surroundings in raising the pups. This can also lead to the rats eating their own babies.
Why Do Rats Eat Their Babies?
The reason why rats eat their own babies can fall under the following major causes. The first cause is the lack of infant care in rats. The second reason is the limitation of food resources. And, the third cause is rats’ wicked behaviour.
Cause 1: Lack of infant care in rats
According to epigenetics studies, it has been seen that there occurs a huge change in a Glucocorticoid Receptor (GCR) gene leading to gradual demethylation in that gene if a mother rat properly cares for her babies during their initial growth stages. This makes the gene highly active and making the pups survive and respond well in stressful conditions.
And, those pups that were not given much attention do not express the GCR gene. As in them, this gene remains highly methylated and inactive and so leading the pups to respond poorly to the various stressful conditions.
So, from such epigenetics studies, it has been observed that mother rat’s care of her babies can highly influence their health. And, those pups that are devoid of care mostly during the first week of growth and development are more prone to disease, unhealthiness, and being killed by the mom for food.
Also that during the various environmental stress situations like high vibration and noise conditions in the surroundings, poor humidity regulation, poor ventilation or air conditioning, and also due to the various disturbances around parturition leading to the dip in their hormones like oxytocin can lead to the rats eating and killing their babies.
Also due to fear of potential predators or new invading males in their colony, due to urgent need to escape from that habitat, disturbance by noise or rough handling can also lead to various complex behavioural patterns in rats causing neglection of the young ones.
Also, if a mother rat can’t nurse her cubs or find food for them, and so, as a result, if one of her cubs dies, then she’ll most likely eat it immediately. This will provide her with food nutrients in the diet along with the benefits of removing the dead bodies so that no potential predators are attracted to their burrows.
It has been also seen that those female rats who were bred for the first time, sometimes get panic by seeing their newly born babies and get confused by considering the pups as foreign bodies. This causes them to go under stress leading to killing and eating the pups.
Sometimes if anybody touches the pups, a foreign smell will be there on the body of pups, and so the mother can also get confused and eat them. Such cases are reported in laboratories and genetically modified rats a lot.
It is to be noted that in rats, the mother-infant bond formation is strengthened by various social stimuli between the pups and the mom. Such as tactile stimuli and ultrasonic vocalizations (USVs) from the pups to the mother, and feeding and tactile stimulation from the mother to the pups leads to mother-infant bond formation.
Oxytocin is the hormone that plays a key role in such mother-infant bond formation. So, Postpartum Depression (PPD) leading to a disturbance around parturition can cause a huge dip in the oxytocin hormone in the mother’s blood which can lead to the mother showing a lack of infant care and eating of her pups.
Cause 2: Limitation of Food Resources
In many of the rats, there has been observed that the mother takes less care of those infants that are born immature or unhealthy. While she is much more likely to take care of the healthy ones.
In general, those infants that are born healthy and mature will take a time period of anywhere between 18 to 21 days to leave their mother’s milk.
So, this time period of 18 to 21 days includes the period of nursing the pups by the mom and their eventual weaning at the end.
But, in the case of immature unhealthy pups, nursing and weaning time can vary anywhere between 28 days to 32 days or even more.
So, it has been observed that due to the limited resources in the environment and also due to the various ecological pressures there is less involvement of the mother in taking care of immature infants because it will need more food resources, nourishment time, and nutrition for the mom to deliver the infant with enough milk for an extended period of time, which can also lead to change in mothers annual life cycle routine.
Under such conditions, mother rats can show a complex pattern of behaviour leading to the killing and eating of those immature and unhealthy pups and making themselves devoid of affective involvement with their pups.
Cause 3: Rats’ wicked behaviour
Mother rats are also seen feeding and licking the little hairs or bristles growing from the face or snout of the pups. An extensive feeding of such a type can also go on to ear or toe chewing of the pups, and from there to total killing and feeding of the pups.
Perinatal learning and recognization of maternal odour are required for the pups to approach the mother and attach to her nipples for nursing purposes.
And mother rats are sometimes seen choosing not to milkfeed their pups due to their various complex behaviour resulted from the various stressed situations.
Females begin breeding as soon as they are five weeks old. They enter into their heat phase approximately after every three weeks, and during this time they can mate 500 times in 6 hours.
Another thing is that their resulting pregnancy usually lasts for about three weeks or so, and the litter size typically ranges from 6 to 20 pups per birth.
So, it has also been seen that they don’t bother much about the pups, especially the new bred females who are almost new to giving birth.
So, under such a condition they can show complex behavioural patterns like ignoring the pups, killing them, eating them alive, not breastfeeding them, etc.
Also that, during situations of the scarcity of food the rats (both males and females) can also opt to fight with one another and killing the young pups in the nest for feeding on them.
It has been also known that rival rat packs can compete against each other for areas where there is food. So rats from another pack can also attack the young pups and feed on them during the time when there is less amount of food available to them.
Also, if anyhow the young pups die, then rats are also known to eat their dead bodies to prevent the smell of rotten corpses from attracting predators to their place.
When she is stressed, she may also choose to clean and lick her babies hardly and instinctively and keep them warm very often. Although this can initiate the bonding process between the mom and babies, but doing this in a very hard, rapid, and instinctive way to these small ones can sometimes kill them and so later on, the mother may choose to feed on them.
EXPLAINED: About Cannibalism in Rats
The phenomenon of eating of one animal by another animal member of the same species is called Cannibalism in zoology.
According to evolutionary biology, Cannibalism aids to serve as a prominent mechanism in order to control the population of a particular species in the ecosystem.
Here, if we talk about Cannibalism in rats, it is to be noted here that rats kill each other under various circumstances and feed on them.
Most often the young ones are killed by their mom or other invading rats for food purposes.
While it has been also noticed in the wild that the dominant males may kill the females and feed on them if they reject mating with the males or during the time when food is scarce.
The cause of this Cannibalism by the mother is not known with exact certainty, but yes, maternal hormone imbalance may play an important role in this case.
Also, reasons like maternal stress-related symptoms, disturbance around parturition, problems with humidity regulation, the improper surrounding temperature, scarcity of food, malnutrition, etc. also play a key role here in Cannibalism in rats.
In the most simple words, if we say, Cannibalism in rats and other rodents is very frequent to occur during drastic conditions like less availability of resources such as food, shelter, proper habitat, territory, etc. as a way to regulate population numbers.
Now, it has also been reported that mothers may selectively cannibalize their malformed offspring in order to have enough room and resources available for the well-formed offspring to survive.
How to stop rats from eating their babies
There are various possible ways to stop rats from eating their babies. but yes, none of these techniques work 100% in solving the problem well:
1. It has been seen that rats in the labs breed best when the temperature inside the room is between 17°C to 26°C, and the humidity level is between 40% to 60%. Such conditions can cause very little to no Postpartum Depression (PPD) conditions in the mother and so can avoid cannibalization of the pups.
2. It is always suggested that we limit the handling of both the pups and the mother and let them stay under their own custody, reduce noise and vibrations around their habitat, limit bright light conditions, and also limit any other smells around their habitat. These won’t cause the mother to cannibalize the pups under stress.
3. A foreign smell on the pups can confuse the mother, so we must always avoid touching the pups with bare hands or it may confuse the mother into thinking that the pups are foreign bodies resulting in her killing and feeding on the pups.
4. In the labs, we must ensure that lights are not used very often and that researchers and technicians do not enter the mouse room during the dark cycle. This will work the best in maintaining the light-dark cycle and so reducing the risk of Cannibalism.
5. It has been seen that the very best way to keep rats and their pups together when a consistent and uninterrupted light-dark cycle of 14-hour light/10-hour dark cycle or 12 light/12 dark cycle is commonly maintained. This will aid them to breed in the best way possible typically in the lights off duration making them think that it is night and so there will be fewer chances of killing the pups and feeding on them due to breeding and nurturing stress.
6. Sometimes due to scarcity of food, proper nutrition, lack of proteins, etc. they go under stress and so cause cannibalism. So. it is best suggested to provide them with a balanced protein diet with at least 13 g of protein per 100 g of food contents providing well-balanced nutrients.
7. Also by offering extra environmental enrichments such as extra bedding, a shack/house, tunnel, or paper tissues to the pregnant mother rat can also result in decreased cannibalism rate and so decreased pup mortality and increased pup maturity very soon.
How do rats react to dead rats?
Rats do use a variety of techniques like using high-frequency sounds and their sense of smell to communicate with each other. By doing so, they become very closely attached to other rats and so can very well recognize their own family members.
Rats are social animals, so they are often seen to getting depressed if left alone or when their mates die in their rat family.
They may enter into deep grief and suffering due to the loss of their friends or mates. This can be seen when they totally stop taking care of themselves, and their pups sometimes, and also they stop grooming each other while in grief.
They may even refuse to eat food they used to love, or they may not react at all thus lacking to take care of themselves in sudden grief. This has been reported in the various wild researches that were being conducted on rats.
Such, situation of sadness lasts for only about 3 to 4 hours maximum as reported. And that they may find various ways to get rid of the dead bodies of their dead mates. One such way is cannibalism.
So yes, in many of the stress conditions they may choose to eat the carcasses of the dead rats following the way of cannibalism.
This will help them to get the nutrition in the case of scarcity of food, or can even help them to get rid of the various potential predators who may be attracted to their burrows following the smell of the dead rotten bodies.