Mad cow regulations deprived vultures of carcasses to feed off, reversing revival of European populations, say researchers
Giles Tremlett, guardian.co.uk 30 Nov 09;
Europe's carrion-guzzling vultures should be allowed to return to their old jobs as nature's waste managers, according to scientists who say the birds are suffering as they increasingly depend on being fed by people.
Stringent regulations brought in because of mad cow disease in 2002 meant the carcasses of dead cows, as well as sheep, goats and other livestock, could not be left in the open. Carrion was crucial part of the vultures' diet, but the birds now do much of their feeding at managed carrion centres set up by authorities.
The change means a gradual, decades-old revival of vulture populations around Europe is grinding to a halt. Vultures fed by humans find it harder to reproduce and farmers complain some have taken to attacking live animals.
"The effects of this policy include a halt in population growth, a decrease in breeding success, and an apparent increase in mortality of young age classes," a group of Spanish researchers said in a letter to Science magazine.
Population growth has flattened out over the past decade after two decades in which vultures, which had been systematically poisoned by farmers, had flourished. The number of griffin vultures in Spain, for example, increased from 3,500 pairs to 18,000 between 1979 and 1999.
Last year 20,000 pairs were counted but there is evidence that populations have begun to decline rapidly. One observatory near Segovia, central Spain, reported a 40% drop over five years. Another observatory in La Rioja, northern Spain, reported an 80% drop, and says local vultures have stopped reproducing completely.
Spain, which is home to 90% of Europe's griffin, cinereous and bearded vultures, has asked the European Union to relax the ban on leaving dead livestock where they fall. "For centuries there was no problem in leaving carcasses out," said Juan Antonio Gil, of Spain's Bearded Vulture Foundation. "The vultures cleaned them up."
"Now carcasses have to be collected and disposed of centrally, with all that means in terms of costs and the energy used," he said. Rather than spend money on tractors, trucks and diesel fuel, he said, the task could be done for free by vultures.
"The most efficient and ecologically friendly way to dispose of carcasses it to let the vultures do the job," he said.
