The Wing-Sac Odour of Male Greater Sac-Winged Bats Saccopteryx bilineata (Emballonuridae) as a Composite Trait: Seasonal and Individual Differences

Abstract

Male Saccopteryx bilineata possess a sac-like organ for the storage and display of odoriferous secretion in their front wing membrane. Since males use the scent in agonistic and courtship activities, and compose it from different secretions of distinct sources, like saliva, urine and gland secretion, we hypothesized that multiple information is encoded in the male scent-profile. We expected that the odour profile of males varies seasonally, giving information on male reproductive status. In addition, the odour profile ought to vary between individuals, thus providing the possibility for individual recognition. We repeatedly collected samples from wing-sac liquids of 20 male S. bilineata in five Costa Rican colonies during the mating and non-mating season. Samples were analysed by gas chromatography coupled to mass spectrometry to compare wing-sac contents. Wing-sac odours included various substances such as carboxylic acids, terpenoids and aromatic compounds. Male scent profiles varied (1) between seasons in the relative amount of tetradecanoic and octadecanoic acid, and (2) between individuals in the relative amount of two species-specific substances. These results suggest that the wing-sac liquid of male S. bilineata is indeed a composite trait and may be useful for the simultaneous transfer of multiple information.