Table 2.

Behaviors scored in home-cage observations and air-horn tests.

Behavior	Measure	Definition
Approach	Frequency	Move to within 10 cm of infant
Solicit	Frequency	Position body directly above or against infant and/or attempt to pull infant onto body
Carry	Duration	Infant has all four limbs on any part of female's body
Reject	Duration	Rub, pull, or otherwise try to force juvenile off body (excludes biting)
Inspect	Frequency	Push face against or toward infant and/or use hands to investigate infant (excludes grooming)
Lick	Frequency	Common usage; lick any part of infant's body
Vocal threat (erh-erh)	Frequency	Low-pitched, staccato chattering; performed in the context of offensive or defensive aggression (Epple, 1968; Stevenson and Poole, 1976)
Attack	Frequency	Lunge at or pounce on infant aggressively
Bite	Frequency	Direct biting motions towards infant
Cuff	Frequency	Swift, superficial blow, scratch, or push performed aggressively
Bristle strut	Duration	Arching posture and/or strut locomotion and/or general piloerection
Scratch self	Frequency	Common usage; direct scratching toward any part of body
Autogroom	Frequency	Use hands and/or mouth to pick through own fur, mouth, or other body part
Long-call (phee)	Frequency	Long, high-pitched, whistle-like contact call; most commonly performed during separation from a familiar groupmate(s) (Epple, 1968)
Chirp	Frequency	Any tsee, tsik, twitter, or chirp vocalization; associated with high arousal; may be used as alarm/mobbing calls (Epple, 1968; Cross and Rogers, 2006)
Ngä (infant)	Frequency	Infant emits relatively low-pitched, atonal, infantile squeal; associated with distress or used as a contact call
Locomotion	1-min scan	Engaged in locomotion or other whole-body movement
Proximity	1-min scan	Any part of female's body is <10 cm from infant
Suckling	1-min scan	Infant's mouth is on female's nipple and/or infant's face is in vicinity of female's nipple