Auklets and penguins:

Birds use feathers 'to touch'

by Matt WALKER

Birds may use their feathers for touch, using them to feel their surroundings just as cats use their whiskers.

The revelation that feathers have this hitherto unknown function comes from research on auklets, birds that sport prominent plumes on their heads.

Auklets with bigger crests, that stick out further, bump into things less.

A wider analysis suggests that numerous birds, from parrots, penguins, pheasants and hummingbirds, also use their feathers to feel their way.

Details of the discovery are published in the journal Animal Behaviour.

Many species of bird sport elegant long feathers, either crests, beards or whiskers that adorn the head and face, or striking tail feathers.

Many of these feathers are thought to have a sexual function, being used to advertise a bird's virility to potential mates.

But Dr. Sampath Seneviratne of the University of British Columbia in Vancouver, Canada and Professor Ian Jones of Memorial University in St. John's, Canada suspect they may also have a tactile function.

Bumping heads They explored why a group of birds called auklets have evolved such elaborate head feathers.

Within the genus Aethia, a number of species have different shaped feathers, but both males and females tend to look the same. The birds usually breed in dark, rocky crevices.

The researchers placed individual auklets into a dark experimental maze, designed to resemble a natural crevice, and recorded how often they bumped into things.

Both crested and whiskered auklets bumped their heads 2.5 times more often if their feathers on their heads had been artificially flattened.

Also, "without the aid of the crest, naturally long-crested individuals had more head bumps than short-crested individuals," Dr Seneviratne told the BBC.

The two ornithologists then conducted a wider comparative analysis: checking which bird species sport long ornamental feathers against their lifestyles and where such birds live.

What emerged was a striking pattern.

"Birds that live in complex, cluttered habitats and are active at night tend to have a greater probability to express such facial feathers," says Dr Seneviratne.

"We found a highly significant correlation for the observed trend." Penguins to parrots The pattern held true across all non-passerine birds, which comprise about half of all bird species. The researchers did not include passerine, or perching birds, in their analysis.

That means that various species of penguin, parrot, cormorant, owl, hummingbird, kingfisher, woodpecker and game birds such as partridge and pheasant, may all use certain feathers for touch.

Such species have facial feathers variously called crests, beards, whiskers, rictal bristles and orbital plumes.

Dr. Seneviratne and Prof Jones suspect that similar feathers, such as the long streamers found on birds of paradise or the pin and forked tails of other species, and even protruding feathers on some birds' wings, may fulfil a similar function.

Biologists have long wondered and debated why birds have long ornamental feathers.

Many do so for camouflage, as a warning to startle predators, or to advertise their prowess.

For example, "long facial feathers are generally thought to be 'sexy ornaments' used to seduce choosers and for assessment of the presenter," says Dr Seneviratne.

Cat's whiskers but while such feathers may have acquired these functions, their original purpose may have been to provide a similar function as a cats' whiskers or a blind person's cane.

By providing sensory feedback to a bird about its environment, such feathers can provide a distinct advantage, particularly to birds living in dark or crowded environments.

"Birds living in complex habitats are likely to encounter greater density of objects or clutter that they have to avoid." So such feathers could help birds avoid bumping into burrow ceilings, tree branches and undergrowth.

Feathers around the face would prove especially useful, as they might stop a bird damaging vital organs, such as eyes, eardrums, nostrils and bill.

"We describe the first comparative evidence for this widespread but entirely overlooked sensory function of long facial feathers.

"We argue that this provides a hitherto missing explanation for the origin of ornamental feathers," says Dr. Seneviratne.

- BBC