Horns 'have sheep ramifications'

Soay lambs can be left vulnerable if they grow horns too big

Having an early advantage in life is no guarantee of success, Edinburgh scientists studying wild sheep on St Kilda have found.

Male Soay lambs which grow big horns and so would be expected to be the strongest as adults are more likely to die if their first winter is harsh.

Young rams which put lots of energy into growing big horns may be the most vulnerable to extreme cold and hunger.

Edinburgh University experts are studying Soay sheep on Hirta, St Kilda.

Matthew Robinson, of Edinburgh University's school of biological sciences, who led the study, said: "Young rams are taking a gamble by putting lots of energy into growing horns, which may pay off if their first winter is mild.

"However, if the winter is a difficult one, lambs with big horns are most at risk."

Researchers monitored the wild sheep over a 17-year period for the study, funded by the Natural Environment Research Council, the Wellcome Trust, the Biotechnology and Biological Sciences Research Council and the Royal Society.

The findings, from the universities of Edinburgh and Cambridge and the Macaulay Institute in Aberdeen, are published in the journal Current Biology.