We have a blackbird in our garden without tail feathers, do they have a function to help the birds balance? He seems to be using alternate wings now to maintain his balance. He can still fly but isn't as agile on the ground.
24 July 2012
Sent in by Julie Campbell, Southampton
A bird's tail is a wonderful tool with many different functions. As you've seen, a bird can fly perfectly competently without a tail, but a tail-less bird does kind of lack in 'finesse'. This is because the tail provides it with a rudder and a brake.
One cannot but admire a swallow in flight. The graceful silhouette, the tight twists and turns as it catches flying insects, the fast and accurate way it flies around a farmyard and into the building where it has built its nest - all made possible by the highly manoeuvrable deeply forked tail.
When you get a chance to watch a red kite or a buzzard on a thermal, watch the tail closely. While the rest of the bird hangs motionless in the air, the tail is almost constantly on the move. Tiny changes in the position of the tail ensure that the soaring or hovering bird stays on course, either spiralling up a thermal or leaving the thermal to glide over the countryside.
A spread-out tail increases the surface area of the flying bird significantly, making gliding a lot easier. This is why you see collared doves with all feathers spread out when they glide. Also, many birds dip and spread their tail as they approach a perch or the ground to make a graceful landing. I have watched tail-less birds, mainly fledglings, make rather comical landings as they fall forward being less able to control the forward motion when they stop.
This brings me to the next use for a tail - a means of balancing. Birds use the tail as a counter-balance as they land, and as a means of balancing when they walk/hop on the ground and when perching. Birds like woodpeckers and treecreepers have specially stiffened tailfeathers, and they use their tail as a prop, enabling them to perch and climb on vertical tree trunks.
Another function for the tail is in display - some species appear to use it as a posturing device when defending a territory, but it is mostly for showing off to potential mates. While tropicbirds have two long, slim tail feathers for the job which don't appear to interfere with the bird in any way, the extreme tail of the peacock must be quite a cumbersome appendage, especially as peacocks are woodland birds in their native range of the Indian sub-continent.
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