EDWIN WAITA A wildlife conservation group is trying to dissuade herders in central Kenya from poisoning cattle carcasses to target predators because vultures often end up being harmed and not lions. Poisoning is one of the chief causes of death for Kenyan vultures. Four of the East African nation's eight vulture species are critically endangered. One of those, the hooded vulture, has seen its population plunged by nearly 90% over the past 45 years, said scientist Darcy Ogada of The Peregrine Fund conservation group. Herders usually poison carcasses because they hope lions will return to the kill. Sometimes they do,…