Figure 2. Levels of grooming between resident animals and between resident and stranger animals.

According to the three conditions, the hourly distribution of grooming frequency is reported as follows: male-OUTmale (grooming interactions between males of the observed groups and outgroup males), male-INmale (grooming interactions between males of the observed groups during the visit of outgroup males), and male-BL-INmale (grooming interactions between males of the observed groups recorded in absence of outgroup males) (a). According to the three conditions, the hourly distribution of grooming frequency is reported as follows: female-OUTmale (grooming interactions between females and outgroup males), female-INmale (grooming interactions between females and ingroup males during the visit of outgroups), female-BL-INmale (grooming interactions between females and ingroup males recorded when the outgroup males were absent) (b). Solid horizontal lines indicate medians; length of the boxes corresponds to inter-quartile range; thin horizontal lines indicate range of observed values. Only statistically significant values are reported on the figure. Single asterisk (*): p<0.05; Double asterisk (**): p<0.01.