The scent of love: Unlocking the power of fertile odour to boost ruffed lemur conservation

Zoos play a crucial role in contributing to lemur conservation via ex situ conservation breeding programmes, but mismatches between captive and wild environments can impact upon breeding success. We aimed to develop a novel scent enrichment based on female fertile odours to enhance welfare and breeding success of captive ruffed lemurs (Varecia spp.). We identified 12 volatile compounds from the anogenital odour secretions of a female red ruffed lemur (V. rubra) distinguishing the fertile chemical profile, using solid-phase microextraction and gas chromatography-mass spectrometry techniques as well as simultaneous choice bioassays, which we used to develop a biologically-relevant scent enrichment. We presented this enrichment to four zoo-housed groups of red ruffed and black-and-white ruffed (V. variegata) lemurs. We assessed the effects of the scent enrichment by combining behavioural observations with faecal endocrinology (measuring cortisol and testosterone). We found a significant increase of olfactory behaviours and a significant decrease of inactivity after presenting the enrichment. Faecal cortisol concentration also increased significantly, which could be indicative of sexual arousal rather than stress. We also found that sexual behaviours significantly increased and, crucially, mounting was triggered in males and two females became unexpectedly pregnant following our study. Faecal testosterone concentration increased but not significantly. Overall, we therefore argue that our newly designed scent enrichment has the potential to improve conservation breeding practices and success in zoo-housed ruffed lemurs.