Table 1.

Predictor variables tested in the GLMMs. Model 1 refers to the GLMM shown in table 3, which tests sharing and non-sharing samples together (n = 79). Model 2 refers to the GLMM presented in table 4, using only food-sharing samples (n = 33). Model 3 refers to GLMM presented in table 5, contrasting food-sharing and grooming samples (n = 182).

model	name	score	definition	n
1,3	sex of subject	male	subject is male	46, 102
		female	subject is female	33, 80
1	age of subject	adult	age >15 years	51
		subadult	age ≤15 years	28
1	monopolizability of food	high	food clumped in one piece or cluster	37
		low	many food clusters, but single cluster is defendable by one individual	42
1	food share	yes	partners share food	33
		no	partners do not share food	46
2a	bond type	bond	sharers are bond partners	24
		non-bond	sharers are not bond partners	9
(2a)	CRIa	continuous	mean CRI over two consecutive quarters of the year	33
2a	kin relation	kin	sharers are kin-related	18
		non-kin	sharers are not kin-related	15
2a	sharing direction	receiving	subject receives food	20
		not receiving	subject does not receive food	13
2b	sex combination	F–F	sharers are both female	10
		M–F	one sharer is male, the other is female	14
		M–M	sharers are both males	9
2b	food category	meat	meat is shared	13
		not meat	non-meat resource is shared	20
3	behavioural context	control	resting or social feeding without food sharing	71
		groom non-bond	grooming with a non-bond partner	34
		groom bond	grooming with a bond partner	44
		food share non-bond	sharing food with a non-bond partner	9
		food share bond	sharing food with a bond partner	24

^aIn a control run of model 2a the continuous variable Composite Relationship Index (CRI) replaced categorical variable ‘bond type’ in model 2a (see Material and methods).