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Last Updated: Thursday, 3 November 2005, 18:35 GMT
Climate response risks to nature
By Richard Black
Environment Correspondent, BBC News website

Puffin with its beak full of fish.  Image: BBC
Many species are shifting at an inappropriate rate, and this must in the end be detrimental
Marcel Visser
Some animals are responding to climate change in ways which could threaten their survival, a new study finds.

Scientists showed that migration and breeding of the great tit, puffin, red admiral and other creatures are moving out of step with food supplies.

The researchers say the rapid pace of climate change, together with pressures on habitat, make it difficult for species to adapt.

The study is published in the Royal Society's journal Proceedings B.

A large number of studies in recent years have shown that the behaviour of plants and animals is changing in response to climatic alteration.

Birds are migrating at different times, flowers and larvae are emerging earlier, and fish and insects are moving into new ranges.

The key question is how much this matters - whether these changes impair the prospects for these species, or whether they are appropriate adaptations which will ensure survival.

Marcel Visser, from the Netherlands Institute of Ecology in Heteren, and Christiaan Both, from Groningen University, have trawled through more than 50 research papers to find examples where it is possible to measure the suitability of how a species responds.

Eat or be eaten

"We wanted to find species for which we have some sort of yardstick to assess how much they should be responding," Professor Visser told the BBC News website.

"For example, we know that great tits are changing their behaviour because of the availability of food, so that should be the yardstick here; but there might also be instances when issues such as predation are more important."

Visser and Both identified 11 cases with an appropriate yardstick, and found that in eight of these the species in question is either responding more or less than would appear to be optimal.

Caterpillars are the staple food for infant great tits; and as the emergence of caterpillars in the European Spring is getting earlier, so, logically, should the time at which great tits lay their eggs.

In fact, one population that has been extensively studied, at Wytham Wood in the UK, has brought its egg laying forward, but by too much. By contrast, another population at Hoge Veluwe, in the Netherlands, is laying at the same time as in previous years.

Neither of these responses appears to be the best available for the bird.

In North America, the wood warbler has not adapted its migration pattern to the earlier emergence of caterpillars in its breeding ground; and in the Netherlands, the honey buzzard is also failing to exploit the earlier appearance of wasps which it eats.

The red admiral butterfly, however, is arriving on the UK's shores earlier from its winter grounds in north Africa; but the staple food of its larvae, the common nettle, continues to flower at the same time each year.

Loss of synchrony

The reasons why these species do not appear to be adapting optimally are unclear.

They may be unable to, they may not be subject to a pressure large enough to induce change, or each may be subject to several pressures pushing them in contradictory directions.

Whatever the explanations, Marcel Visser believes his findings sound a clear warning.

"The conclusion must be that many species are shifting at an inappropriate rate, out of synchrony with their food sources, and this must in the end be detrimental.

"The point has often been made that temperatures have increased before in the Earth's past; but the rate now is 100 times greater.

"And whereas in those times there were large areas of natural habitat, now it's much more difficult for animals to change or migrate; plus there's loss of genetic diversity, habitat fragmentation - it's just much more difficult for species than 1,000 years ago."

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