The Evanescent Bouquet of Individual Bear Fingerprint

SIMPLE SUMMARY: The evanescent chemical communication is conveyed by peculiar signals, namely pheromones. These are produced by a particular gland and are mixtures of signals that are physiologically essential to life and together constitute characteristic signatures of both species and individuals. This communication is ancient, and is little studied in mammals, mainly due to the difficulty of identifying the molecules. In this study, we collected the entire bouquet of wild bear putative pheromones from all production sites and analyzed the entire raw extract to profile the individual, species, and sex fingerprint. Our study allowed us to take a step forward, compared with the few papers in the literature, in the study of the complexity of the chemical communication of a solitary endangered species. ABSTRACT: The evanescent and invisible communication carried by chemical signals, pheromones, or signature mixtures or, as we prefer, the pheromonal individual fingerprint, between members of the same species is poorly studied in mammals, mainly because of the lack of identification of the molecules. The difference between pheromones and the pheromonal individual fingerprint is that the former generate stereotyped innate responses while the latter requires learning, i.e., different receivers can learn different signature mixtures from the same individual. Furthermore, pheromones are usually produced by a particular gland, while the pheromonal individual fingerprint is the entire bouquet produced by the entire secreting gland of the body. In the present study, we aim to investigate the pheromonal individual fingerprint of brown bears in northern Italy. We collected the entire putative pheromone bouquet from all production sites in free-ranging bears and analyzed the entire crude extract to profile the individual fingerprint according to species-, sex- and subjective-specific characteristics. We were able to putatively characterize the brown bears’ pheromonal individual fingerprints and compare them with the partial pheromone identifications published by other studies. This work is a step forward in the study of the complexity of chemical communication, particularly in a solitary endangered species.