Table 2.

Ethogram of aggressive behaviours adapted from Stewart et al. (2008)

Behaviour	Detailed description
Aggressive biting1	Biting any part of another sow (except vulva), but not as a part of head thrust
Vulva/anogenital region biting	Biting the vulva/anogenital region of another sow whilst chasing her
Head knocking1	Ramming or pushing another sow with the head (with or without biting)
Fighting1	Mutual pushing parallel or perpendicular, ramming or pushing of the opponent with the head, with or without biting in rapid succession. Lifting the opponent by pushing the snout under its body
Chasing2	Moving rapidly in pursuit of another sow
Threat2	Being in head-to-head contact with another sow
Avoidance2	Sow actively withdrawing in response to head-to-head threat of another sow

¹‘Contact’ aggressive behaviour

²‘Non-contact’ aggressive behaviour