Text Box: Some birds may well live for over 80 years Older than us!! (BBC sciences and nature -May 2009)

Text Box: Unlike humans, birds do not go grey or develop wrinkles. If their outward appearance does not change, how can we tell their age? In most cases ringing provides data on lifespan and longevity. Natural clues to the precise age of a bird are few and only serve to chart survival into adulthood - not beyond. Small birds replace distinctive juvenile plumage with that of an adult within months of being born. After this, their looks do not alter. Larger birds take several years to reach maturity during which time they grow progressively more adult-like feathers. Brown juvenile gannets acquire white plumage resembling their parents' through a series of moults over a five-year period.

  

 

 

 

 

 

 

Text Box: The only known change in appearance linked to old age occurs in captive drake wildfowl. For some bizarre reason geriatric males develop female features, a trait never noticed in free populations. In the wild, because of the overriding mortality from shooting, it is difficult to estimate the natural lifespan of ducks and geese. For example, based on ringing recoveries, most shot teal are between one and three years of age. Comparatively few reach ten years or more: an age structure shown by non-quarry species such as barnacle geese (with 30 per cent of individuals in protected populations aged ten and over).  

 

Text Box: Safeguarded from predators, disease and other life-threatening factors, birds in captivity can outlive human owners. So far, the record goes to a sulphur-crested cockatoo in London Zoo, which was over 80 years old when it died in 1982. In the real world it is a different story. By and large, the smaller the bird the more eggs it lays and broods it raises in an attempt to reproduce itself.