Attracting the opposite sex is not the only reason some birds have elaborate head ornamentation. Avoiding things that might bump your head in the dark is also important, at least for crested and whiskered auklets 鈥� seabirds famed for their decorative head feathers.
Charles Darwin suggested that elaborate display feathers were involved in sexual selection, and subsequent experiments confirmed his idea. In fact, elaborate feathers may have first evolved for touch sensing, with sexual selection coming later, says of Memorial University in St聽John鈥檚, Newfoundland, Canada, who did the research with , now at the University of British Columbia in Vancouver, Canada.
Crested and whiskered auklets nest in hollows on rocky islands in the remote northern Pacific Ocean. To see if their elaborate headdresses helped the birds make their way through the rocks to their nests at night, Jones and Seneviratne went to the Aleutian Islands, captured wild birds and put them in a darkened maze 鈥� but first they taped down some birds鈥� decorative feathers.
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Head banging
Infrared camera recordings (see video) showed that whiskered auklets () bumped their heads nearly three times more often if their long head feathers were taped down. Crested auklets (), suffered similarly with their crests taped down, but adding an artificial crest to the naturally unadorned least auklet () 鈥� which also nests on the islands but in more open areas 鈥� didn鈥檛 help these birds avoid bumps. Moreover, Sereviratne says, 鈥渂irds with longer crests had greater difficulty in navigating inside the maze鈥� when their crests were taped down.
The evolutionary origin of the birds鈥� elaborate head feathers supports the idea that their first job was sensing, says Seneviratne. He adds that the auklets鈥� crests evolved from filoplumes, long hair- or thread-like feathers that lack normal feather structures and are attached to pressure-sensitive cells so they can detect touch. In many birds these feathers are hidden by larger contour or wing feathers, but in the auklets they stick out proudly where they can detect obstacles.
The paper 鈥渋s an interesting and probably a valid interpretation,鈥� says ornithologist Alan Brush at the University of Connecticut. He notes that some birds that catch insects on the wing have facial bristles thought to help them collect prey.
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