Behavioural Correlates of Lemur Scent-Marking in Wild Diademed Sifakas (Propithecus diadema) in the Maromizaha Forest (Madagascar)

SIMPLE SUMMARY: Many animal species use body odours and secretions to communicate with conspecifics. In this study, we observed wild lemurs (diademed sifakas) to understand how and where they deposit scent marks, and whether rank and sex influence the scent-marking behaviour. We found that lemurs deposit their scent marks by rubbing different parts of their bodies, and that the deposition pattern varied according to both sex and social status of the individuals. In particular, we observed that dominant individuals often deposited glandular secretions along with urine when marking, and that the most common areas for marking were the anogenital and chest regions, with chest rubbing being more frequent in dominant males. Males also showed longer and more complex scent-marking sequences compared to females. Moreover, we found that lemurs preferred tree trunks and marked at a similar height, regardless of age or sex. Our results suggest that this species uses a mix of glandular secretions and excreta to increase the probability of signal detection by conspecifics. ABSTRACT: Scent-marking through odours from excreta and glandular secretions is widespread in mammals. Among primates, diurnal group-living lemurs show different deployment modalities as part of their strategy to increase signal detection. We studied the diademed sifaka (Propithecus diadema) in the Maromizaha New Protected Area, Eastern Madagascar. We tested whether the scent-marking deposition occurred using a sequential rubbing of different body parts. We also tested if glands (i.e., deposition of glandular secretions) were more frequently rubbed than genital orifices (i.e., deposition of excreta) by comparing different kinds of rubbing behaviour. We then investigated if the depositor’s rank and sex affected the sequence of rubbing behaviour, the height at which the scent-marking happened, and the tree part targeted. We found that glandular secretions were often deposited with urine, especially in dominant individuals. The probability of anogenital and chest marking was highest, but chest rubbing most frequently occurred in dominant males. Markings were deposited at similar heights across age and sex, and tree trunks were the most used substrate. Males exhibited long and more complex scent-marking sequences than females. Our results indirectly support the idea that diademed sifakas deploy a sex-dimorphic mixture of glandular secretions and excreta to increase the probability of signal detection by conspecifics.