Sex lives of grey seals boosted by warming climate

It's an ill climate change that blows nobody any good, or so seals have been discovering. For global warming has been making them hot in more senses than one.

Research shows that warmer temperatures and reduced rainfall have dramatically improved their sex lives, strengthening them genetically and thus improving their prospects as a species.

A nine-year study by researchers at Durham and St Andrews universities just published by the Royal Society, the country's top scientific body, shows that climate change is allowing many more males to seal the knot, as it were, and is giving females a much greater variety of sexual partners.

Grey seals living off the Scottish coast gather on remote islands to mate each October and November. Traditionally, the dominant males are the only ones to score, each lording it over a harem of 10 to 15 females, which they guard jealously against other suitors.

In the past, they have found this easy, as their harems have always clustered close to them. However, the research - on the island of North Rona, 50 miles north of the Outer Hebrides - shows that global warming is changing all that.

Autumn on the island has normally been wet and windy, but less rain is now falling as the climate warms up, leaving fewer pools of fresh water for the seals to drink and use to cool off. So the females have to go further to reach them.

This takes them out of the area guarded by the dominant males, allowing the weaker, subordinate ones a look in. As a result, the number of males fathering pups has gone up by 61 per cent in the driest years. This, in turn, is increasing and strengthening the genetic diversity of the population.

Dr Sean Twiss, of Durham University, says: "The effects of climate variation on temperature and rainfall has widespread implications for many species, as there are very few animal populations whose mating patterns, and levels of polygamy, are not intimately linked to resource distribution.

"These findings show that climate change - while endangering many species - could also help to increase the genetic diversity of some of them, giving a leg up (or over!) to males who would not normally be so successful."