Death is a part of life on the Mara. Each summer, 500,000 Wildebeests perish along the treacherous migration from the Serengeti in Tanzania to the Mara in Kenya. And with the death come the scavengers, none more important than the vulture. But the birds that once feasted on that misfortune, the janitors that clean the grassy plains, are collapsing — part of a broader decline in vulture populations that throws ecosystems out of whack and illustrates how far reaching the effects of poaching, poisoning and other human interventions can be. “The overall global picture for vultures is abysmal,” said Dr. Darcy Ogada, the Assistant Director of Africa Programs at The Peregrine Fund. “Does this story echo that of the canary in the coal mine? Sure does.” In the first major study of the 30-year decline of pan-African vultures, Dr. Ogada and other scientists found that populations of eight species of vultures had declined an average of 62 percent. Seven of those species had declined at a rate of 80 percent or more over three generations, according to the study, published this summer in the journal Conservation Letters. In some parts of Africa, vultures are targeted by poachers who poison carcasses hoping to kill the birds so they will not circle overhead and signal park rangers. A vulture can spot a dead elephant in less than 30 minutes. It can take a poacher more than an hour to hack off ivory tusks. No vulture, no advanced warning. Here in the Mara, the vultures are not directly targeted but are the unintended victims of poisoning meant to kill large carnivores, like hyenas, in an effort to protect livestock. Across Africa, the threats to wildlife are myriad, but much of the attention is focused on the stately animals of the savannah, like lions and elephants. Vultures do not make for pretty postcards, and local authorities are already stretched thin trying to protect the iconic animals that tourists come to see. “Everyone forgets about the Ugly Betties of this world,” said Dr. Munir Z. Virani, who directs the Africa and South Asia programs for The Peregrine Fund. “We are told all the time by the authorities that they are so busy working to protect elephants and rhinos and other animals that when it comes to the vultures, they are exhausted.” Anthony Ole Tira, who is Masai, was raised on these lands and is now the co-owner of the Matira Bush Camp in the heart of the reserve, stood by a river crossing and pointed to scores of rotting carcasses. One week earlier, 900,000 Wildebeests, long in the face and often short on luck, had plunged headlong into the river in a panic. Thousands were trampled to death. That was normal. The rotting remains are not. “Ten years ago, this would have been cleaned by now,” he said. “There are a lot of places along the Mara River that are not as clean as they once were because there are not enough vultures.” Researchers say they have seen what happens to an ecosystem when the vultures disappear. In 2000, Dr. Virani was dispatched to India. Vultures were dying in great numbers but no one knew why. “Everywhere I went, there were dead vultures,” he said. “But everywhere, their remains were in good condition.” The initial hypothesis was that some type of infectious disease must be behind the deaths. Soon it became clear that the killer was manmade. A painkiller widely used to treat livestock was poisoning the birds that fed on their carcasses. One carcass with the painkiller in its system could poison hundreds of birds, and by 2006, when the painkiller was officially banned, the vulture population had already declined by 97 percent, Dr. Virani said. Over the same period, there was a drastic rise in cases of rabies, with feral dogs taking advantage of the decline in vultures and often spreading disease to humans. Dr. Virani described apocalyptic scenes, with wild hordes of dogs numbering in the thousands, scavenging the remains of the beasts. Estimates vary, but some put the feral dog population in India now as high as 25 million. Roughly 36 percent of the world’s rabies deaths - the majority of them children — now occur in India, according to the World Health Organization. The battle against the virus is costing the government billions of dollars. Over tens of millions of years, vultures have evolved into the most efficient cleaners in the natural world. Because of their highly acidic gastric juices, they can eat flesh infected with a variety of diseases without getting ill. When the vultures feast on diseased meat, picking the carcass clean down to the bone, the threat of wider infection ends. But once the vultures are cleared from the skies, they are very hard to bring back. Dr. Virani explained that vultures, despite their powerful digestive systems, are fragile. Within the first four weeks of their lives, 50 percent of newborn vultures who leave the nest will die. “They are naïve,” Dr. Virani said. Many fall from their nests. Others succumb to natural causes. In the first year of life, vultures have an extraordinary 90 percent mortality rate. If they survive, they do not become sexually mature until their fifth year. Even then, their reproductive rate is low. In Arizona, Utah and California, The Peregrine Fund and its partners have been working for years to bring back the critically endangered California Condor, which by 1987 was almost completely wiped out by lead poisoning, with fewer than two dozen birds left. Nearly three decades later, there are around 400, fewer than half of them in captivity. In Africa, Dr. Virani hopes that the population decline can be halted and reversed before it reaches the kind of critical situation found in India and other parts of the world. “It is not too late,” he said. The Peregrine Fund has started a program with the Masai to change attitudes about using poisons. They supported a young Masai man, Eric Ole-Reson, to study at Clemson University, and he has since returned to work with other Masai. There are few things more important to the Masai than their cows. “The movable bank,” Mr. Tira calls them. When a cow is killed by a lion or other predator, it is a threat to a family’s livelihood. So the Masai will poison carcasses in the hope of killing the killers. Inevitably, vultures come to feed and die. Ole Sairowa, 67, a village elder, said that the use of poisons actually started two decades ago when the government provided “a dangerous white powder” to kill feral dogs. A decade later, he started to notice fewer vultures. “Now we are worried they are not coming back,” he said. Mr. Sairowa was recruited by Dr. Virani and the Fund’s Kenyan Director, Kabir Dhanji, to play a part in a short educational film about the unintended dangers of using poison, “Empty Skies,” that will be shown in villages across the Mara. Mr. Tira and his 9-year-old-son, Selian, also star in the film. Mr. Sairowa said that when he was a boy, they would sing songs to the vulture. Long been prized for their ability to see into the future, the appearance of a vulture could be a good or bad omen, depending on the context. The song asks the vultures to stay away until a cow meets its natural end, at which point they are promised a tasty feast. Conservationists are working to find other ways to help the Masai protect their cows, testing a system of solar-powered flashing lights to ward off predators at night. But other threats remain. Dr. Virani cited the intensive effort to bring electricity to power-starved communities across Africa through the construction of wind farms and power plants as another effort that, if not carried out carefully, could endanger vultures and other large birds. For now, the vultures - which in flight look every bit as majestic as the beloved eagle — continue to play their role in the natural drama that unfolds during the migration. On a recent morning, as first light broke over fields of red oat grass on the savannah, a female lion let roar. A male lion returned the call, and the hunt was on. By the time it was over, five wildebeests had met their end, their carcasses obscured in the tall grass. It only took a few minutes for vultures to begin circling overhead. First two, then a dozen, then scores. They waited until the lion began walking away before swooping in and perching near the carcass. The vultures pounced. In 20 minutes, the bones had been picked clean. It seemed efficient. But Mr. Tira said the job used to be accomplished much faster, by many more vultures. “In five minutes, they would be done,” he said. “If the vultures continue to disappear, can you imagine? This whole, beautiful place will become on stink pit.”