I think that we can break this down into 3 headings (1) kitten play-fighting (2) dominant males or females in a group and submissive cats (2) grown-up siblings who have become independent and no longer regard each other as siblings.
Kitten play-fighting
The question in the title probably refers most to sibling kittens play-fighting. This is rough-and-tumble and it can get quite aggressive. Some kittens will complain by screaming at the aggressor. In this way it is said the kittens know where the limits are to their play fighting. I have a video I made at A1 Savannahs which amply demonstrates this behavior. These are F1 and F2 Savannah cats. They are more athletic and alert than typical domestic cats because of their wild cat inheritance which is one or two generations removed. It explains the screaming 😎.
This is social play and often it is inhibited or modified versions of behaviour patterns typically seen in aggressive encounters between independent cats who are strangers to each other (in defending territory – play-fighting) and alternatively during predation (play-hunting). It seems, to me, that kittens are practising their skills in respect of establishing their home range and defending it against strangers. That’s why you see kittens often bouncing around sideways in the crab-walk in presenting the largest possible area of their body to their imaginary aggressor.
During the first 3 weeks of social play at 4-7 weeks of age, 3 or more kittens might usually be involved in bouts of play. As they mature, they tend to play-fight in pairs. This form of social play peaks at about 9-14 weeks of age.
Social play escalates more often into aggressive interactions after 10-12 weeks of age. And at about 14 weeks of age social play declines and is replaced by what is called ‘object play’. Object plays occurs when kittens develop their eye-to-paw coordination and play with small objects and toys.
When the kittens have been weaned and rehomed, they might direct their desire to play-fight with their new owner or other companion animals in their new home.
The adult cat, treated as a kitten by their owner, sometimes feels the need to play with the human companion and it often means aggressive play with biting. It is play nonetheless but the owner might consider to be an aggressive attack.
Dominant males or females in a hierarchy
There appears to be no ranking hierarchy in domestic cats but you will see dominant cats behaving more aggressively than the others in a social group. It seems to me that if in a group of siblings, one becomes dominant they may impose their will on the other siblings through what is called resource guarding and control. In doing this the behaviour will seem antagonistic and some people may interpret this as siblings fighting.
Independence
When siblings are truly independent, they would normally, if they were wild cats, leave the natal home range to find their own territory to establish and defend. Typically, in the wild cat species, the male cats travel further and establish larger territories than the females who tend to set up home near the natal range and may even stay within their mother’s range. But at this stage if there are 2 male siblings establishing their home range they may come into conflict and at that time the fact that they are siblings will not inhibit their behaviour to maintain their territory.
If a cat owner keeps a litter of cats to adulthood and within that litter there are 2 male cats, they will need to find a home range within a very small space namely a house or even perhaps an apartment. Normally a male domestic cat might enjoy many acres as their home range and therefore to be limited to a space the size of a room is going to be difficult and there may be friction between 2 male siblings in trying to carve out their own space and defend, one against the other.
Of these 3 headings, there’s no doubt in my mind that observers may mistake the social play aspect of their lives as pure fighting because it entails a lot of fighting – in training for the real thing – but there’s a cap on how far they go in their aggression. And, as mentioned, we see this in adult cats when playing with their human caregiver. A cat might nibble their caregiver’s hand in play but it won’t be a full-blown aggressive bite.
P.S. Human children, particularly boys, like to play-fight a lot. It is the same thing I guess; instinctive training for the real thing when they are adults.
Below are some more pages on feline play.
