Supplementary Material for: Do Common Marmosets (Callithrix jacchus) Use Scent to Communicate Information about Food Resources?

Many animals use olfactory cues to signal information about food resources; however, this particular use of scent has received little attention in primates. Common marmosets (Callithrix jacchus) are exudativores that gouge bark to elicit exudate production and frequently deposit scent marks at gouge holes. We conducted preliminary tests of the hypothesis that common marmosets use olfactory cues to communicate information about exudate value, with more desirable resources targeted for marking. We performed choice experiments on two captive male marmosets. The animals were presented with: (1) a urine scent-marked and unmarked food resource, and (2) a high and low value food resource (i.e., greater/lesser food volumes). Marmosets placed more scent marks on high, compared to low, value food resources. Animals also spent more time gouging, removed more bark and more frequently revisited high versus low value food resources. Lastly, scent-marked foods were gouged more often than unmarked foods. Our findings support the hypothesis that marmosets use scent marking and olfaction to convey information about food resources, although verification in a larger sample is needed. Nonetheless, the demonstrated link between food value and scent marking suggests that olfactory signals may aid marmoset foraging decisions.