Magazine article Geographical

Questions and Answers

Magazine article Geographical

Questions and Answers

Article excerpt

IT'S A BIRD'S LIFE

Q: We often hear that life expectancy for men and women is increasing. Has any research been done into the changing longevity of animals and birds, and if so, what are the findings?

A: While many of us are aware of the reasons behind our increasing longevity, we are less familiar with changes in the life expectancy of birds and animals. Because many birds and animals do not live for very long, researchers talk about annual survival rates rather than longevity, since this is a more useful measure. Research has shown that survival rates for some species are increasing, while those for many others are decreasing (sometimes dramatically). A range of factors influence survival including predation risk and disease. For many species, human exploitation of the world's resources has caused survival rates to fall by reducing food availability and by altering the balance within delicate ecosystems. Even the annual survival rates of familiar species like the Song thrush and House sparrow have been found to be declining.

Mike Toms, RSPB

A: Research into the changing longevity of animals and birds suggests it is those features that help an animal evade predators, or survive if the environmental conditions become harsh, that will make its species evolve a longer lifespan. Previous research had suggested that it might be an animal's metabolic rate that determined its lifespan, but this was superseded by the theory of effective body maintenance and repair, as it was realised that birds and some mammals (including humans) lived for much longer than their metabolic rate indicated.

Frank Muscat, Malta

STORMY WATERS

Q: Why is the Black Sea so called and how did it get its name?

A: The Black Sea's name was not derived from the colour of its water, but rather because it is more stormy than its southern sea cousins. Its name in the Greek language was originally Pontos Melas, which translates as `inhospitable sea, unfriendly sea'. …

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