A critically-endangered species of deer, which has taught itself to walk using only two legs for fear of sinking in the floating biomass of Loktak lake here, is on the verge of losing its last home in the world, warn experts.

Made up of continuous floating biomass vegetation, the Keibul Lamjao National Park (KLNP) situated inside the lake is the only remaining natural habitat of the 'Sangai', also known as the 'dancing deer' for its unique artistic manoeuvring abilities inside the fragile swamp.

However, negotiating the world's only national floating park located 53 km from here in Bishnupur district is getting dangerous for the brow-antlered deer, whose population is estimated to be less than a hundred.

"Not only has the size of the biomass or 'phumdies' been decreasing over the last few years but its buoyancy and thickness is also getting reduced by the day. The chances of 'Sangais' getting drowned have increased manifold as the capacity of the KLNP to support its weight has decreased," environmentalist R K Ranjan told PTI here.

At places the 'phumdies' have become as thin as one metre. If a Sangai steps on it in search for food or shelter, the 'phumdy' might not be able to sustain its weight leading to its drowning, he says.

This has also restricted the mobility of the elegant deer, increased in-breeding, and made it compete with other wildlife for food, admits Manipur's deputy conservator of forests L Joykumar Singh.

Inside the park spread across an area of 40 sq km, the area deemed safe for 'Sangai' is restricted to merely 9.5 sq km. .

According to the last census conducted by the Wildlife Institute of India in 2008, the mean population of the deer, once declared extinct, has fallen down to an alarming 92.

Ecologists blame the changing nature of 'phumdies' on the hydrological changes in the eco-system which occurred after the water level in the lake was kept at a higher level for NHPC's hydro-power project.

"This increase in water levels has brought the 'phumdies' farther away from the ground making it difficult to draw nutrients from the river bed and support vegetation," N C Talukdar, director of Institute of Bio-resources and Sustainable Development, says.

He warns that with rising temperature due to global warming will lead the biomass to decompose quickly and further reducing its thickness.

Another critical issue for survival of this deer species is pollution in the lake water.

"Besides complicating birth, pollution might result in deformities among the deer. They might even acquire genetic defection, says wildlife expert Kh Shamungou.

A report by Wetlands International holds the inflow of pesticides, chemical fertilisers and domestic sewage as responsible for the deterioration of water quality.

The blocking of the water outlet at Ithai barrage has further aggravated the situation as the freshwater lake is now no more than a water reservoir wherefrom the pollutants can't flow out.

Besides the deteriorating health of the wetland, poaching and encroachment along the KLNP area is also a major concern.

In 2010, six poachers were arrested from Khorda after they had laid a big net to trap the animal, say wildlife department officials.

Over the years, Sangai is also struggling to find food for itself after invasion by a plant known as 'para' grass.

"Para grass expands very quickly and prevents the growth of other plants. The species is invading fast and the more area it covers the less food will be left for Sangai," warns Ranjan.