With their hunched posture and baldheads, vultures are associated with death. But they are the unsung cleanup crew in Africa. Without them diseases would spread and the Maasai Mara Reserve with smell like a slaughterhouse. But in the last 30 years even African vulture species have declined by over 80%. Pastoralists angered by attacks on their cattle by lions lace the carcasses with poison. 60 % of vulture deaths have been due to poisoning. Follow a team trying to save them during the annual wildebeest migrations.