Table 1.
Description of behavioural patterns.
| Social interest | |
| Approaching: | The focal mouse moves directly towards the partner mouse until the distance between both is less than one body length (frequency). |
| Facial/body sniffing: | The focal mouse contacts the head/body of the partner mouse excluding the ano-genital region (duration). |
| Ano-genital sniffing: | The focal mouse contacts the ano-genital region of the partner mouse (duration). |
| Following: | The focal mouse locomotes after the partner mouse, while its head is directed to the latter’s backside. The maximum distance between the animals is one body length (duration). |
| Aggressive behaviour | |
| Chasing: | The focal mouse performs “following” at a fast running speed mostly subsequent to an agonistic interaction, while the partner mouse displays “fleeing”. The maximum distance between the animals is two body lengths (duration). |
| Attacking: | The focal animal contacts the body of the cohabitant with its mouth, making it react with winced movement of either single extremities, the tail or the whole body (not counted during escalated fighting) (frequency). |
| Escalated fighting: | Physical struggle between focal and partner mouse that usually involves kicking, wrestling and rolling over and over (active/passive individual not determinable) (frequency). |
| Defensive behaviour | |
| Avoiding: | The partner mouse performs “approaching” and the focal mouse moves away immediately (within 1 sec), thereby changing its speed or direction (frequency). |
| Fleeing: | The focal mouse moves away from the cohabitant at a fast running speed, mostly after the partner mouse has displayed an aggressive behaviour. Meanwhile it can perform leaps and jumps (duration). |
| Defensive upright posture: | The focal mouse rears up on its hind paws and keeps still, with the forepaws rigidly stretched out towards the partner mouse (only qualitative). |
| Threat behaviour | |
| Tail rattling: | The focal mouse makes fast waving movements with its tail (only qualitative). |
| Other behaviour | |
| Mounting: | The focal mouse places its forepaws on the back of the partner mouse and mostly performs pelvic thrusts (duration). Please note: mounting can be driven by sexual motivation but is also displayed in an agonistic context. As this could not be distinguished, it is listed as “other” behaviour. |
| (For descriptions of behavioural patterns see also)5,15,25–29. | |