Fig 1.
Photographs of stone and shell tools with tool surfaces labeled: P—points, E—Edges, and F—faces.
The use of shell tools was scored as either point or face only.
Table 1.
Behavioural and material components of Burmese long-tailed macaque tool use.
Table 2.
The hammering classes and tool-use action patterns of Burmese long-tailed macaques.
Fig 2.
Our data indicated differences in behavioural elements across hammering classes in average a) bout duration, b) number of strikes, c) strike rate, and d) size.
Panel e) shows that the proportion of bouts exhibiting smooth recoil, the use of both hands, the use of precision grips, striking towards a different plane, and seated posture differed across hammering classes as well. Letters are used to denote statistical significance. Each letter groups bars into non-significant groups within each analysis, and thus significantly different bars to not share letters. Error bars represent one standard error of the mean.
Table 3.
Means and standard deviations for all variables for each hammering class.
Table 4.
Results of Kruskal-Wallis H and Mann-Whitney U tests for differences between hammering classes.
Fig 3.
A comparison between use on sessile and unattached foods within both face and edge hammering classes showed differences in behavioural elements across food types within edge hammering, and less so in face hammering.
Edge hammering on sessile food resembled axe hammering as c) strike rate was faster, d) tools used were smaller, and e) a higher proportion of bouts exhibited smooth recoil, precision grips, and striking towards a different plane. Face hammering on both food types resembled pound hammering, except in panel e) face hammering on sessile foods had a higher proportion of bouts with smooth recoil than on unattached foods. Asterisks indicate significantly different bars. Error bars represent one standard error of the mean.
Table 5.
Means and standard deviations for all variables when face and edge hammering were carried out on sessile and unattached food types.
Table 6.
Results of Mann-Whitney U tests for differences within face and edge hammering when carried out on sessile and unattached food types.
Table 7.
The number of individuals observed to use each hammering class and action patterns from scan samples, the percentage of the population that this constitutes, and average percentage of individuals’ tool-use scans in which each pattern was recorded.
Fig 4.
Scan sampling indicated differences in the proportion of point, face, or edge hammering used across five groups.
Letters are used to denote statistical significance. Each letter groups bars into non-significant groups within each analysis, and thus significantly different bars do not share letters. Error bars represent one standard error of the mean.