Buffaloes love mud. It keeps them cool and protects their delicate skin from the sun. When the squelchy stuff is scarce, they dig down to reach groundwater and make their own.

The tireless churning of one herd on Lantau, the largest island in Hong Kong, has turned a parched field into a swamp full of lush green floating plants. It is a haven for insects and birds, including white egrets that perch on the buffaloes' backs. Many Hong Kongers cherish these animals and the photogenic touch they add to the island's largely undeveloped wilderness. But some would prefer to get rid of them.

Water buffaloes are not indigenous to Hong Kong. They were introduced to the territory when it was a British colony, probably from Southeast Asia, to work as beasts of burden in the rice paddies. In the 1970s the animals were abandoned — along with the fields — as rural people gave up farming for jobs in towns.

Today, around 120 feral buffaloes live in Hong Kong, alongside 10 times as many of their bovine cousins, brown cows. The cows roam widely but the buffaloes are confined to small wetlands on the south coast of Lantau and in the northwest New Territories, an area of the Chinese mainland that falls under Hong Kong's jurisdiction.

The cows and buffaloes are classified by the government as "stray," not as a protected species. That means the government is supposed to impound them. But it prefers not to have to take on the burden of looking after them.

So it sterilizes the animals and tries to keep them away from places where they might cause harm. The buffaloes are generally docile, but they are huge and have big horns, which the bulls use when battling each other for dominance.

Randy Yu, a local politician, said many of his constituents grew up with the animals and so have "mixed feelings" about them. Although they are fond of them, they find them a nuisance and complain that the government is not doing enough to control them.

Rural groups propose relocating the animals to Tai A Chau, an uninhabited island near Lantau that was a former refugee detention center. Yu said some should be sent to the islet on a trial basis. The government is not keen: Tai A Chau is not a good bovine habitat and monitoring their welfare there would be bothersome. Urbanites who regard the animals as part of Lantau's rustic charm want them to stay, too.

Some of those who would prefer that the animals be removed are motivated by more than just concern about the damage they cause. Some Hong Kong villagers (only men) enjoy historical rights to build houses on their ancestral land. But zoning laws make it difficult for them to do so on farmland.

The government said it is all for preserving Lantau's paddy-turned-mudbaths. But it also wants to find land where homes can be built to ease the territory's shortage of housing.

Eventually, the buffaloes may have to abandon their idyll.