Table 2.

Operational definitions of behaviors analyzed

Behavior	Description
Defensive behaviors
Defensive vocalizations	Calls consisting of shrill barks, shrieks and squeaks
Cower	Withdrawal to the periphery of the cage in a crouched or recoiled position with an upward directed gaze
Escape	Sudden movement/startle response, typically consisting of moving explosively from one side of the cage to the other
Social behaviors
Grooming-related behaviors	Subject presents for grooming, receives grooming from the conspecific or actively grooms the conspecific
Approach	Initiates social contact; moves body or head towards the conspecific
Mounting	Mounts the conspecific
Aggression	Makes threatening gestures (i.e. mouth threat, head or body lunge, cage shake) towards or hits, grabs or bites the conspecific
Play	In contact with the conspecific, includes chasing, wrestling and ‘rough and tumble’ behaviors
Withdrawal	Moves away from the conspecific when approached
General (non-social) behaviors
Locomotion	Walk, runs, climbs or jumps
Passive	Inactive, stays in one location
Distance between animals (scored in parallel with the above categories)
Social Contact	Non-incidental and consistent touch between subject and conspecific (can include grooming related behaviors, mounting, play or passive sitting when in contact with the conspecific)
Proximity	Subject sits or stands at arms length from the conspecific
Alone	Subject sits or stands isolated from the conspecific