Aggressive Behavior - Biting & Nipping

The reason for this article is because the question of biting and nipping in the rat keeping community is generally brought up quite frequently for a variety of reasons.

It is unusual for rats to bite out of fear or aggression, but under certain conditions this can happen. Generally speaking it is rare to get a rat that was just born nasty, however this can occur. Rats that have a history of biting should never be used for breeding purposes, no matter how excellent their colour or coat is, the biting trait is generally passed on to the offspring.

The following are reasons that biting may occur and the reasons usually found to be the root of the cause.

Finger Nipping – Finger Nipping is a common problem in the rat community, partly due to a rats poor eye sight and because people feed their animals through the bars of a cage. This is not classified as true biting, but merely an accidental nibble. It is in eagerness to accept the treat that this occurs, the rats generally releases the nip as soon as the realisation sets in that a finger has been grabbed along with the food, although a hard nip may be felt it is unintentional on the rats part. This kind of nip rarely if ever draws blood as the rat would exert much more pressure with its teeth if the nip was intended to be a bite. While giving treats such as ice cream, yoghurt etc that may cover the fingertip, then it is understandable that the rat may not be initially aware that your finger is under all that yummy food.

There are some occasions where a rat will bite hard when a hand comes close, with or without food or a treat. Generally this is because the rat that has done the biting is not confident with your hand being so close. Fear of being grabbed is powerful in an animal that is on the bottom of the food chain(especially if they have not been handled regularly). The bite is the result of this particular animal feeling like it needs to protect itself from the “unknown hand” and not from plain aggression. Caution and patience must be given to a rat that has trust issues, with time and love they will learn to love you as much as you love them. Using a short word or comforting sound before offering food by hand can be a great tool to gaining this animals trust, this will give the rat time to understand what is about to happen and not react so defensively towards your offering. You know what your intentions are, but the animal has not yet learned to understand that, or may need to get familiar with the approach manner of a new human carer. Approaching an uncertain rat from above may trigger an instinctual need to protect themselves and because of this we recommend approaching any rat from the front. Natural predators approach from above (ie birds) so rats, even domesticated rats, maintain some of their instinct when it comes to things coming from above.

Female Rats – Female rats make excellent mothers, however, to be an excellent mother she needs to provide, not only warmth and food for her young but also protection from predators including her human family, not all mothers show this level of protection with people that they have strong bonds with. This biting behavior can begin during the final part of your females pregnancy, the behavior normally stops once the babies have been weaned and mum will return to her normal non-biting self. On rare occasions a female that is nursing young may deliberately go out of her way to attack humans. This behavior may not have been present previous to her pregnancy or with her previous owner (if the rat was acquired as an adult). Change of environment and hormonal changes that occur during pregnancy and nursing would appear to be the reason for this behavior. Again it is not recommended that you breed from this female again. It is important to still communicate with a pregnant or nursing female that is showing aggression. Talking to her and allowing her to seek you out while you are not invading her “space” will help with keeping a good relationship with the female.

Male Rats – Male rats unfortunately have the worst reputation when it comes to people’s personal thought on rats. Although most males are very affectionate and cuddly there are those that are considered by most people as just plain nasty!!. I am about to tell you that although some males can appear plain nasty, almost to the point of not being able to be rehabilitated, there is hope. Some male rats, when they reach sexual maturity will exhibit aggressive posturing and will attack other rats and people without the slightest amount of provocation. Their general demeanor is one of hunched posture, legs tucked under the body and motions in short strides, head held close to the body and their hair all puffed out to make themselves look bigger and stronger. They will scent mark anything and everything they go near, rubbing their body against any surface they can and may also stay in one spot for a short period and scratch vigorously with their front hands. Should they come into contact with bare human skin of any kind (hands, feet, arms etc), then this vigorous scratching will be the prelude to biting and ripping of skin. When another rat becomes the object of their aggression, then the attack will not stop no matter how bloody they become. They will inflict serious injury, and even possible death, on other rats, even if others have indicated full submission to them and will continue to fight with total disregard to their own injuries. This is the worst case scenario, it can occur, with some rats not reaching quite this level of aggression. The rats with this type of behavior issues are normally classified at just plain nasty, but in fact they have little to no control over it at all as it is generally cause by the body chemistry of that particular rat. The level of male hormone, testosterone, which is relatively high in males with these behavior issues, is the cause of their behavior. Rats displaying this behavior must be housed alone for their own and other rats safety. These rats will generally try to attack through cage bars so caution must always be used while working around the cage. A thick towel can be used to place over the rat to avoid being bitten while moving them to give you access to the cage for cleaning and food top ups etc. As the rat ages the body chemistry will slowly change, you will notice the aggressiveness become less, but this will take some time. Neutering your overly aggressive male in these circumstances is the only approach that is widely accepted within the rat keeping community, the effects of the neuter can normally be seen as early as 2-3 weeks after surgery as the hormone levels drop sufficiently for the rat to return to “pre-hormonal” behavior and you can consider intergrading him in with females, or back into a cage with males. Intergrading must be done slowly and cautiously, following the same rules of introduction as you would for newly acquired rats. We recommend that any signs of early hormonal issues be dealt with promptly (with a neuter) so that the male can stay with his group without having to be kept alone and re-integrated.

Additional Info – A well adjusted and well socialised rat should not bite no matter what age it is. Sometimes a recently acquired rat may bite out of fear or it may simply hide and indicate a reluctance to interact with its new family or other new cage mates. Once you get to know your new rat, you will notice the individual personalities of each animal differ greatly like those of humans. Some rats are outgoing, adventurous, playful, while others are more quite, subdued and inclined to snuggle up under you top and sleep close to you. Their personalities are influenced greatly from birth by their pecking order from most dominant to least dominant in the litter. When biting, or in most cases nipping occurs, then patience, understanding and gentle handling (with the aid of a bribe such as a tasty treat) will allow the rat to become use to you and trust you. Loud and sharp noises, such as those from young children or barking dogs, in their environment, will cause stress to the rat and make it difficult to handle. While working with a rat that is jumpy and unsure, it is best to find a quite area that is also escape proof and spend some quality time with your new friend.

Young female rats approaching sexual maturity do not show the same aggressive behaviors as males, but they can be the cause of more frequent fighting between the cage mates. It is not uncommon for young female rats to try to mount other females in their cage, often with resistance from the other rat or rats. This will often lead to fighting as they persist with attempts. They will soon grow out of this behavior as they mature fully.

Biting by both Male and Female rats can also be an indicator of pain caused by an injury, illness or when recovering from an operation, especially when the rat has always shown to be comfortable with you and has never bitten before. If there is no obvious reason for such action, then it will be worthwhile to have the pet examined by a vet as this can be a sign that something is going on internally with your rat that you have not yet detected with you fortnightly checks.

Rats have also been known to become aggressive when kept in cages too small for them. Please always ensure that your rat or rats have enough space to play, eat, toilet and sleep. Where a rats aggression is based on the size of the cage, the problem can generally be corrected with a larger space and some training in socialisation for your rat.

Pet rats do not bite unless there is a reason, and once the reason is known, an approach can be investigated to correct the behavior, making life for you and your little ones a lot less stressful and more fun.