When we think of sexual selection in birds we usually think of colour, song and their associated displays, but what about scent? A functional sense of smell has been exhibited by every bird that has been tested, yet the study of chemical signalling in birds has been historically neglected (Hagelin et al. 2003, Roper 1999). It has now been shown that some species of seabirds display olfactory discrimination capabilities, suggesting that scent may provide valuable information as to the quality of prospective mates and also be used as an inbreeding avoidance mechanism (Mardon & Bonadonna 2009).
The Blue Petrel (Halobaena caerulea) has been shown to prefer the odour of its mate and other conspecifics than that of itself (Mardon & Bonadonna 2009). This odour recognition and preference could serve many functions but it has been suggested that it may be used to facilitate genetically based mate choice (Mardon & Bonadonna 2009, Zelano & Edwards 2002). Olfactory signals from urine or body odours have been associated with certain genotypes in many species of vertebrates, meaning that chemical signalling may be also playing a role in mediating mate choice in birds (Mardon & Bonadonna 2009, Singh 2001).
The Crested Auklet (Aethia cristatella) emits a tangerine-scented odour during the breeding season that is thought to be used as a method of chemical communication (Hagelin et al. 2003). Throughout the courtship period both sexes emit this odour and frequently engage in 'ruff sniff' displays where individuals rub their beaks in the nape feathers of display partners, the region where the tangerine odour is the strongest (Jones & Hunter 1993). The fact that this scent is only produced, and 'ruff sniff' display only occurs in the breeding season, provides strong evidence that birds are using olfactory cues in the process of sexual selection (Hagelin et al. 2003).
So next time you admire the striking colouration of a bird, or listen to a beautiful melody of birdsong, consider that there is often more to birds than meets the eye or ear. I have shown you throughout the blog so far how more well known and studied visual and accoustic-based cues can often be associated with sexual selection. These alone result in a huge variety of intriguing and incredible morphological and behavioural traits, but with olfactory cues thrown into the mix, yet another layer of complexity is added to the wonderful world of birds!
 |
| The Blue Petrel (Halobaena caerulea) may be using olfactory cues to facilitate genetically based mate choice. Image sourced from https://oceanwide-expeditions.com/to-do/wildlife/blue-petrel. Viewed on 18th April 2017. |
The Crested Auklet (Aethia cristatella) emits a tangerine-scented odour during the breeding season that is thought to be used as a method of chemical communication (Hagelin et al. 2003). Throughout the courtship period both sexes emit this odour and frequently engage in 'ruff sniff' displays where individuals rub their beaks in the nape feathers of display partners, the region where the tangerine odour is the strongest (Jones & Hunter 1993). The fact that this scent is only produced, and 'ruff sniff' display only occurs in the breeding season, provides strong evidence that birds are using olfactory cues in the process of sexual selection (Hagelin et al. 2003).
 |
| Crested Auklets (Aethia cristatella) engaged in a 'ruff sniff' display where individuals rub their beaks in the nape feathers of display partners, the region where the tangerine odour emitted is the strongest. Photo by Lars Petersson http://www.hbw.com/ibc/species/54074/photos. Viewed on 18th April 2017. |
So next time you admire the striking colouration of a bird, or listen to a beautiful melody of birdsong, consider that there is often more to birds than meets the eye or ear. I have shown you throughout the blog so far how more well known and studied visual and accoustic-based cues can often be associated with sexual selection. These alone result in a huge variety of intriguing and incredible morphological and behavioural traits, but with olfactory cues thrown into the mix, yet another layer of complexity is added to the wonderful world of birds!
References
Hagelin, J.C., Jones, I.L. & Rasmussen L.E.L. 2003, "A tangerine-scented social odour in a monogamous seabird", Proceedings of the Royal Society of London. Series B: Biological Sciences, vol. 270, no. 1522, pp. 1323-1329.
Jones, I.L. & Hunter, F.M. 1993, "Mutual sexual selection in a monogamous seabird", Nature, vol. 362, no. 6417, pp. 238-239.
Mardon, J. & Bonadonna, F. 2009, "Atypical homing or self-odour avoidance? Blue Petrels (Halobaena caerulea) are attracted to their mate's odour but avoid their own", Behavioral Ecology and Sociobiology, vol. 63, no. 4, pp. 537-542.
Singh, P. 2001, "Chemosensation and genetic individuality", Reproduction, vol. 121, no. 4, pp. 529-539.
Hagelin, J.C., Jones, I.L. & Rasmussen L.E.L. 2003, "A tangerine-scented social odour in a monogamous seabird", Proceedings of the Royal Society of London. Series B: Biological Sciences, vol. 270, no. 1522, pp. 1323-1329.
Jones, I.L. & Hunter, F.M. 1993, "Mutual sexual selection in a monogamous seabird", Nature, vol. 362, no. 6417, pp. 238-239.
Mardon, J. & Bonadonna, F. 2009, "Atypical homing or self-odour avoidance? Blue Petrels (Halobaena caerulea) are attracted to their mate's odour but avoid their own", Behavioral Ecology and Sociobiology, vol. 63, no. 4, pp. 537-542.
Roper, T.J. 1999. "Olfaction in birds", Advances in the Study of Behavior, vol. 28, pp. 247-247.
Singh, P. 2001, "Chemosensation and genetic individuality", Reproduction, vol. 121, no. 4, pp. 529-539.
Zelano, B. & Edwards, S.V. 2002, "An MHC component to kin
recognition and mate choice in birds: predictions, progress, and
prospects", The American naturalist, vol. 160 Suppl 6, no. 6, pp. S225.
I’ve never really considered olfaction to be an important sense in birds, so I found this quite fascinating. Both examples you have given are of seabirds. Are there examples from other species that are not associated with the marine environment?
ReplyDeleteYes there are, but it does seem to be an area that has not been as well studied as other cues used for sexual selection. Intraspecific chemical communication has been found to occur not only in seabirds but also in budgerigars (a species of parrot). Recent studies are suggesting that many species of passerine songbirds may be using there sense of smell in many more ways than we previously thought. The primary exocrine gland in most birds is the uropygial gland, or preen gland, which is located above the base of the tail and secretes a substance called preen oil. This oil serves many functions such as repelling predators or parasites, but may also play a role in assessing prospective mate quality. A very interesting subject that still very little is known about!
Delete