KITENGELA, Kenya (Reuters) - A short distance from the slums and skyscrapers of Nairobi, Naanyu Ntirrisa pulls thorn bushes around her Maasai village to keep out marauding lions that have killed a cow and two sheep.
"We are doing our best to be vigilant," she says.
Across a river from the village, tourists in Land Rovers photograph giraffes munching on acacia thorns, with the city's towers visible in the distance.
They are enjoying the charms of Nairobi National Park, the closest of its kind to a capital city in the world, where visitors can grab a quick safari during a business trip and airlines even take stopover passengers out for a game drive.
Airliners making their final approach fly over vultures wheeling in the sky and zebras browsing with antelopes.
The scene on the Athi plains south of the Kenyan capital is typical of the Maasai lands stretching hundreds of miles to the Tanzanian border.
The park hosts one of the largest concentrations of the rare black rhino in Kenya and lions and even cheetahs can still be seen -- with a bit of luck.
Yet, where plains were once black with thousands of wildebeest on the scale of the famous Maasai Mara migration further south, scarcely a hundred now roam.
The pressure of human expansion is posing a deadly threat to the park, Kenya's oldest, and has led to bad-tempered rows between wildlife organizations, Maasai groups and a microfinance institution trying to help slum dwellers.
The most passionate dispute focuses on a clutch of red roofs sprouting on the windswept plains south of the park, where wild animals and Maasai herdsmen roam.
They mark the first stage of a township where 10,000 residents from Nairobi's huge, squalid slums will live. The town is the brainchild of Ingrid Munro, a Swedish woman who has devoted her life to helping Kenya's poor.
Munro runs Jamii Bora, Kenya's largest microfinance institution. After winning five years of legal battles, Jamii Bora began construction of Kaputiei town last May.
An alliance of the government Kenya Wildlife Service, conservation NGOs and one Maasai group vows to continue the battle, saying the town will destroy the traditional way of life in the area, increase crime, pollute water supplies with sewage and block the corridor by which animals enter the park.
Most of the animals roam on the much bigger plains and come into the park through the open southern boundary for water in its 12 dams during the dry season, but their route is increasingly restricted by fences and settlement.
Munro fiercely rejects the arguments of her opponents, saying the corridor was blocked years ago by palatial houses and fences put up by rich Kenyans and flower, poultry farms and eucalyptus plantations that soak up the scarce water.
"We have owned the land for six years and have never seen a wildebeest," Munro scoffs, denying that the town is even in the corridor. "The truth of the matter is that the migration in and out is not there any more."
She adds: "Some of those who are against us live on the border of the park in huge mansions with private air strips and swimming pools."
But Inge Burchard, of the Friends of Nairobi National Park society says the town "will strangle the park." The group pays compensation for livestock killed by wild animals under a successful scheme to protect predators.
"Maasai will be outnumbered. wildlife and livestock will be poached, crime will increase," Burchard said.
James Turere, chairman of a Maasai group based around the sprawling nearby town of Kitengela, said: "The people who decided on this project, they have killed our future."
"This will make the local community into a minority, it will disenfranchise the community economically, politically and environmentally," said Maasai landowner Ogeli Makui, who administers a scheme paying herders to keep the ranges open.
"We still shed tears when they talk about it."
Deputy warden Richard Chepkwony agrees about the threat to the park. "If they build so many houses they will block the corridor. It is definitely going to be a big problem because it will reduce the (animal) dispersal area."
However, other Maasai in the area of the new town like the project and say Turere is not representative of local people.
"We all support the town because of development and employment," said Joseph Kepiro, leader of the Kisaju Maasai community of 500 families that has joined Jamii Bora to access its loans and support.
Munro angrily rejects claims that the town will create tribal conflict between Maasai and other tribes from the slums "Nonsense, absolute nonsense," she said, adding that the town will be a model for a society free of ethnic tensions.
Jamii Bora is building a milk cooling plant for the Maasai and helping the women to sell their beadwork to retailers.
Even the wildlife conservation community is divided over how to protect the park, with some believing that keeping the corridor open is a pipe dream.
Richard Leakey, a prominent white Kenyan and former head of the KWS, told Reuters: "I don't think a corridor is a realistic option. Development has gone too far."
Leakey says the only way to save the park is to fence it and keep a certain number of animals inside.
But Burchard, the KWS's Chepkwony and many others, including U.S. ambassador Michael E. Ranneberger, say the migratory corridor must be kept open and the 117 sq km (45 sq mile) park is too small to sustain itself.
"If we fence the park we are going to cut off the majority of the animals, they will sweep the park clean. Then what will happen?" Chepkwony asked.