was phased out from the park as far back as 1983. Constraints The Siberian crane, which formerly lived throughout the entire Indo-Gangetic plains of India, is reported to be no longer found in the area. Its absence has been attributed to hunting by nomadic tribes along the species' 5,000 mile migration route from Siberia to Bharatpur. Some 2,500 cattle and domestic water buffalo were allowed in the area up until November 1982 when grazing was banned. Predictably, the ban led to a buildup of local resentment, resulting in an attempted forced entry into the park. Police opened fire and eight people were killed: tensions still remain high. The absence of grazing is causing management problems as vegetation, principally Paspalum distichum, a perennial amphibious grass, blocks up the channels. The Rajasthan government has rejected a proposal from the Bombay Natural History Society to allow limited grazing, since this would conflict with the law. Furthermore, recycled nutrients from the large quantity of dung deposited by livestock probably supported considerable numbers of insects. The presence of some 700 feral cattle within the park is cause for concern as they compete with wildlife for valuable forage. Larvae of the Lepidopteran Parapoynx diminutalis has also been a serious pest, and considerably inhibited the growth of Nymphoides cristatum during June–July 1986. High levels of pollutants in Ajan Bund are believed to be responsible for the increasing number of piscivorous birds seen in a dazed state and unable to fly. Fewer birds were recorded in 1984 than in previous years. Four sarus cranes and 40 ring-necked doves were found dead outside the park during 1988 and early 1989, possibly due to pesticide poisoning, and a study of the impact of pesticide use in surrounding areas on the park has been initiated in addition to studies on heavy metal contamination. Disturbance from visitors can be a cause for concern, especially during December and January when visitors come to see the cranes. A non-native water hyacinth Icornia species was introduced in 1961, and has now proliferated to the extent that it is blocking the artificial waterways and filling the impoundments. This is significantly altering the habitat for many bird species, and is a serious management problem. Attempts to control the species have been ineffectual to date. Tourism and visitor facilities By virtue of being one of the best bird watching sites of Asia, more than 100,000 visitors come to