Signaling across the senses: a captive case study in pair-bonded red-bellied lemurs (Eulemur rubriventer) at the Duke Lemur Center, NC, USA.

We provide a preliminary case study in red-bellied lemurs (Eulemur rubriventer) to illustrate a multimodal approach to understanding communication strategies within a species with obligate pair-bonds. From June to August 2012, we observed and analyzed signaling behaviors across three established red-bellied lemur pairs at Duke Lemur Center (Durham, NC, USA). Our aim was to assess how individuals combine signal modalities to communicate with pair-mates, and to determine whether these strategies vary by time of day, sex, or pair. We analyzed rates of occurrence of touch (allogrooming, mutual grooming, physical contact, and huddling), scent (scent marking and allomarking), and sound (close-distance contact calls) using Wilcoxon rank sum and exact binomial tests. Time of day impacted rates of occurrence across signal modalities, with higher rates of combined signaling within each modality occurring earlier in the day (p < 0.03). Across time periods, all pairs used auditory signals most frequently, followed by olfactory signals, and finally tactile and tactile-olfactory signals (p < 0.01, all comparisons). In fact, auditory signals frequently overlapped the olfactory signaling modality, and travel rarely occurred without accompanying vocalizations. However, red-bellied lemurs spent the highest percentage of their observed time in tactile signaling bouts (on average, 19.5% of total observed time across pairs). Males and females participated equally in most signaling behaviors (p > 0.1), with the exception of scent marking, which males used more frequently (p < 0.01). The results of this study will aid in developing methods and hypotheses to determine how wild red-bellied lemurs communicate to form, maintain, and advertise their pair-bonds.