Tangerine Ruff ‘n’ Sniff: new clue to bird social behaviour

Scientists believe they have opened the door to an overlooked area of bird behaviour – the use of social scents. The basic assumption is that vision and hearing are the main senses that birds use to signal each other, e.g. the colour of plumage; the sound of birdsong. This is questioned by new experimental evidence observed in the Crested Auklet, an arctic seabird.

Research by scientists at Swarthmore College and elsewhere, published in Proceedings B, explored the Crested Auklets’ frequent “ruff-sniff” displays during courtship, where individuals place their bills in the nape feathers of a mate, a region that emits a strong tangerine-like scent.

The citrusy smell of Crested Auklet feathers only occurs during the breeding season. Research showed that the birds were repeatedly drawn to the scent of natural feathers and to the chemical components that make up the auklet’s characteristic odour. The seasonal “ruff-sniff” display, may perhaps act as a useful mechanism to obtain odour information about a potential mate.

Dr Hagelin, one of the paper’s authors, said: “Although odours are a common form of communication in every other vertebrate animal, the possible use of scent to convey social information is an exciting addition to the study of avian behaviour.”

All birds have a functioning sense of smell. There is abundant evidence that birds frequently recognise and respond to odours in their immediate environment when they find food or navigate from place to place. Odiforous feathers are also surprisingly widespread in birds and readily detectable to humans, even though our noses are not as sensitive. . Despite this intriguing evidence, studies have never closely examined the response of birds to their self-produced scents before.

The Crested Auklets are highly social birds and their striking “ruff-sniff” displays are a good place to start. The seasonal display is linked to a part of the body that exhibits a seasonal odour. It may be that other birds also use social odours. For example, mutual preening is a subtle but common behaviour between mates of many species that could result in the transfer of chemical information. For the moment, Dr Hagelin believes that the Crested Auklet’s preference for its tangerine scent could alter how we interpret social behaviour in birds. “Our results provide support for an entirely new mode of signalling in birds, that of chemical communication. It is a means of interpreting bird behaviour that is just beginning to be realised,” she explained.