The hidden speaker was positioned between two wooden rods -- one swabbed with a female's scent and the other 'unscented' -- so that the sounds and the scents came from the same location.
In general, the lemurs paid more attention to the sounds and smells in the matched trials in which the call they heard and the scent they smelled came from the same female, than in the mismatched trials when they heard one female and smelled another.
Both males and females spent more time sniffing and/or marking the scented rods in the matched trials than in the mismatched trials. Males also spent more time looking in the direction of a female's call when her scent was present instead of another female's scent.
The results held up whether the sounds and odors came from a dominant female or a subordinate one.
The ability to tell if the voice they hear corresponds to the scent they smell may help a lemur figure out if the animal producing the scent is still nearby, said Princeton graduate student and coauthor Ipek Kulahci.
Unlike shrieks, yips and wails, odors can linger long after the animal that made them has left the area.
This may explain why lemurs showed more interest in the matched cues than the mismatched cues, Kulahci added.
"If they detect a whiff of a familiar female and she's still within earshot she can't be far."
Herodotus, a male ring-tailed lemur living at the Duke Lemur Center moves toward the sound of a familiar female from a hidden speaker and marks a wooden rod rubbed with her scent (right). He also marks an unscented rod (left), but less frequently and for a shorter period of time.
(Photo Credit: Ipek Kulahci, Princeton University)
A ring-tailed lemur scent-marks a tree at the Duke Lemur Center. Olfactory signals and sounds from female lemurs can throw members of their group into a tizzy. But not all combinations of noises and odors evoke the same response. Ring-tailed lemurs respond more strongly when the scent they smell matches the voice they hear.
(Photo Credit: : Ipek Kulahci, Princeton University)
Source: Duke University