Following on from the diversity of eggs from a couple of weeks ago.. here’s a little blog about the fluffy, streamlined, colourful and perfectly designed world of feathers!
Feathers have been used by humans for hundreds of years as fashion statements, writing implements, pillow stuffings and in every kid’s arts and crafts basics box… but what about their intended purpose, and on their intended owners?
Feathers are unique to birds. Think about that for a second. Since the first feathery dinosaur (previously thought to be the archaeopteryx, but now science’s thinking is that feathers may have been found on species earlier than this, but not fossilised terribly well), birds have retained these specialised structures to enable them to fly, keep warm, attract a mate and camouflage themselves from predators. There are no other groups of animals alive on the planet today with feathers, other than birds, how crazy is that!
Some birds possess feathers specially designed for silent flight: like owls. Their feathers have bizarre serrated edges that break up the air flow and reduce drag, and therefore turbulence, which creates the usual ‘whoosh’ noise when a bird flies past you. Because of this, owls have become specialised hunters capable of sneaking up on their prey (photo below).
Other birds use their feathers for less mechanical reasons, preferring instead to waft, shake, jiggle or fluff their feathers up to attract a mate! The most fabulous example of that are of course the birds of paradise, which come in a myriad of exotic colours and ostentatious patterns. There is a famous outtake of David Attenborough attempting to do a piece to camera about the Greater bird of paradise, which is displaying very loudly above his head! Its bright yellow flank plumes fluffed up, spreading its wings in an arc and hopping about calling magnificently on the branch.
Displays of this extravagant variety are to attract a female and to out-compete other males in their territory, and what a display! Some birds of paradise have taken this ostentatious display to the very extreme, such as the long tailed widowbird or the ribbon tailed Astrapia… which have evolved such disproportionately long tails due to female sexual selection pressures, that they struggle to fly long distances with this feathery baggage! Females will therefore choose the males which are able to support their own weight!
Another bizarre, almost counter-intuitive bit of feather adaptation is showcased by the only non-waterproof diving bird: the cormorant. You heard it right! A diving, fish eating, water visiting bird lacks waterproofing feathers! But there is a method in this evolutionary madness: when cormorants dive for fish, they need to be able to sink to the appropriate depth, and waterlogging themselves makes them heavier, and reduces air bubbles which would bring them back to the surface. That’s why you will often see cormorants with their wings spread open like a pterodactyl on shorelines and on posts, drying themselves out after a morning fishing!