Scientists believe they have discovered the biggest migration of wild animals on Earth, with an aerial survey revealing vast herds of gazelle and antelope on the move in southern Sudan in a region which had been assumed to have been denuded of its wildlife by years of civil war. The Wildlife Conservation Society, together with the autonomous government of South Sudan, announced at a press conference in New York yesterday that a study of the area's fauna had revealed an abundance of antelope, particularly of white-eared kob, in breathtaking numbers. Flying over an area of about 590,000 sq kilometres, scientists witnessed a column of animals in their seasonal migration through grasslands and swamps that was 50 miles (80 km) long and 30 miles across.

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They estimated the population of the white-eared kob - a chestnut coloured and medium-sized antelope - at about 800,000. Add to that other species including the topi and the Mongalla gazelle, and the total number of migratory animals is put at 1.3 million, approaching the scale of one of the world's greatest natural events, the Serengeti migration of wildebeest and zebra across east Africa. "This could represent the biggest migration of large mammals on Earth," said Michael Fay, a field scientist with the WCS, who conducted the survey. "I have never seen wildlife in such numbers, not even when flying over the mass migrations of the Serengeti."

The discovery of wildlife in such gigantic numbers astonished Dr Fay and his fellow conservationists, because the Serengeti migration, which occurs between July and October each year as a way of avoiding the impact of the dry season, was considered to be unrivalled. The findings also came as a happy surprise as the region's long-running civil war had been assumed to have led to environmental devastation. An aerial survey was last carried out in 1982, a year before fighting erupted between the Sudan People's Liberation Army and government forces backed by Arab militias from the north. The fighting lasted for more than two decades and claimed 2 million lives.

In 2005 a tentative settlement was reached between the warring parties which has led to autonomous status for the government of South Sudan, and calm has returned to the area with its population of about 11 million. A referendum is to be held on independence in four years' time. In January, a team led by Dr Kay set out to find out what had happened to the wildlife they had not been able to study for 25 years. Despite the natural richness of the territory, sandwiched between the Sahara and a belt of tropical forests, they expected the worse: there is a long and sorry history of the devastation wrought by poachers and armies during Africa's many wars.

But as soon as the plane was up over the grasslands, at the start of 150 hours of flying, their hearts lifted. Dr Fay said: "If you were a gold miner and hit a vein of gold, like we found in kob, you would have found El Dorado." In addition to the gigantic herds of kob, they produced estimates of 250,000 Mongalla gazelles, a small tan and hite antelope with a black stripe on its flank; 160,000 topi, or tiang, a horned antelope; as well as reedbuck and ostriches. The review of the wilderness's state of health was not universally positive. In the south-west of the region up to 90% of species had been lost.

"We saw no buffalo where in 1981 there were estimated to have been 60,000 and only one group of elephants was sighted, where some 10,000 had been estimated to roam in the past," said Paul Elkan, head of the WCS's programme in southern Sudan. The south-western zone is particularly prone to poaching, whereas the eastern area is protected to some degree by the natural barrier of the Nile and by its swampy terrain. In other parts, zebra populations also appear to have been wiped out. The animal used to number up to 20,000 in the Boma National Park, in the south-east corner of the autonomous region, but were not visible to the survey planes.

The Wildlife Conservation Society, which has numerous global outreach projects but also runs the zoo in Manhattan's Central Park, now wants to build on the survey findings to preserve the extraordinary wildlife that they found. It is calling for the creation of an international conservation mission to protect it. Under the scheme, former fighters with the Sudan People's Liberation Army would be retrained into wildlife activists, managing a network of parks and encouraging environmentally-friendly practices among local villagers.

The project would be called the Sudano-Sahel Initiative, and it has been modelled on work done in the Congo basin, another abundant ecosystem under enormous pressure from civil war and conflict over natural resources. In the case of southern Sudan, the natural resource that most poses a threat to the wildlife is oil. Since the end of hostilities, oil companies have begun to show increasing interest, and several permits have been handed out for exploration - right in the middle of the migratory path of the antelope.

The Serengeti journey
The discovery of the gigantic migration in southern Sudan pits it against one of the wonders of the natural world, the twice-yearly Serengeti migration: Every June, nearly 2 million herbivores begin marching northwards from the Tanzanian part of the Serengeti plain towards the northern hills in Kenya, following the rains to avoid the dry season. Every October, once the higher pastures have been fully grazed, they make the reverse journey back to the now green pastures of the southern Serengeti. The journey is about 700 miles in each direction and the enormous herds include 1.4 million wildebeest and 200,000 zebra and gazelle.

The experience of migration begins when wildebeest are just a few months old. Many animals fall from exhaustion or are picked off by predators during the journey. The most perilous part is the crossing of the Mara river where many are taken by crocodiles, or lions waiting for them on the other side. It had been assumed that the Serengeti migration was unparalleled. But the revelation that there are herds of white-eared kob in southern Sudan in numbers that scientists believe may even exceed the wildebeest herds has challenged that.
(Por Ed Pilkington, The Guardian, 13/06/2007)