Be careful what you eat (Image: Ferrero-Labat/Ardea)

AFRICAN vultures are starting to follow their Asian cousins on a deadly downward spiral.

Munir Virani and colleagues at the National Museums of Kenya, Nairobi, have reported that vultures in and around the Masai Mara National Reserve have suffered a population crash of over 50 per cent in the last 25 years (Biological Conservation, DOI: 10.1016/j.biocon.2010.10.024). Over the same period the number of livestock farmers near the park soared. The pattern of vulture deaths suggests their main threat comes from the farmers, who leave dead goats laced with the toxic pesticide Furadan to kill hyenas and lions.

In south Asia, griffon vultures have been driven to near-extinction by consuming accidentally poisoned cattle carcasses – cows that had been treated before death with drugs that happen to harm vultures. Because vultures range widely and eat communally, only 1 per cent of cattle need to be poisoned to affect the whole population. This makes the use of deliberately poisoned carcasses in Africa even more of a threat to the scavengers.

The irony, says Chris Bowden of the UK’s Royal Society for the Protection of Birds, is that if the poisoned carcasses eliminate vultures, it will help the hyenas and lions that the farmers are trying to eliminate to flourish. That’s because there will less competition for the carrion normally eaten by the birds.