• aggression;
  • dominance;
  • enrichment;
  • male effect;
  • oestrous related;
  • pheromone;
  • scent marking;
  • territorial;
  • volatiles

Pheromones are substances secreted to the outside of the body by an individual and they are used for communication between animals. Pheromones can code for species, subspecies, sexual identity, age and reproductive status, as well as motivational state. Animals also use learned olfactory cues to recognize group membership, kinship and individuality. Pheromones from ♂♂ can enhance reproductive functions in ♀♀. This biostimulation may have great potential to support reproductive management as it could hasten sexual maturity, induce ovulation and reduce post-partum anoestrus and mating. In contrast, ♂-directed oestrous-related signals from ♀♀ exist in many species. These could be used as excellent analytical indicators to predict the receptive period of a ♀. Pheromones may also signal the dominance status of ♂♂. In zoo situations where there is no competitor for the ♂ and, thus, no ♀ mate choice, a complete cessation of reproduction is often observed. To stimulate the presence of another alpha ♂ the confrontation of ♀♀ with odoriferous material of an alien ♂ may reinitiate mating activities. To reduce stress, fear and neophobia in zoo animals scenting enclosures with pheromones can lead to a significant improvement in animal welfare. In many cases, olfactory stimuli were successfully integrated into enrichment programmes in zoos designated to stimulate reproduction or naturalistic behaviour.