The grazing and wallowing habits of water buffaloes may have unexpected consequences when the animals are introduced to new, perhaps fragile environments. The presence of several thousand feral buffaloes on the coastal plains of northern Australia, for example, has become a very emotional issue among Australian environmentalists, some of whom foretell the complete destruction of the environment if the uncontrolled feral herds are not destroyed( It is not at all clear, however, that the buffaloes (which have existed in the area for 150 years) are causing the observed environmental degradation. Other possibilities include: fire, climatic stress, overgrazing, and a variety of farming, hunting, and other human activities, especially the use of four-wheel-drive vehicles. Thousands of wild pigs also share the area, along with crayfish that burrow into and weaken the levees that keep out the sea, something for which the buffaloes have been blamed).
Water buffaloes have larger hooves than cattle of comparable size and thus they compact the soil less. But buffaloes often live in damp, boggy areas where their feet may compact soft soils. Also, buffaloes are creatures of habit and, when able, they set up fixed points for drinking, feeding, defecating, wallowing, and sleeping. Between the points they wear sharply defined trails in the vegetation and soil.
Possibly the water buffalo's greatest environmental limitation is its propensity to build wallows. In hot climates every buffalo will wallow at some time during the heat of the day if water is available. When they can, buffaloes will make their own wallows, enlarging a mud puddle by rolling in it or even using their heads to flip water out of a drinking trough and muddying the ground nearby.
The pasture in the immediate area of the wallow is usually damaged by trampling and waterholes may become fouled, but buffaloes return to the same wallow day after day and do not build new ones indiscriminately. Thus, the muddied area is not a large proportion of the location in which they graze unless a large number of animals are confined in a small space(At Gainesville, Florida (possibly because of its subtropical but not hot climate), a herd of 52 buffaloes concentrated in a one-hectare field did not attempt to build a wallow at ale -Information supplied by H. Popenoe.) . In addition, man-made wallows can be dug at safe sites and the animals will use them. The problem of wallowing is therefore not generally a serious one.
Damage to Waterways
Because buffaloes often live near and enter water freely, they may cause erosion in ditches, river banks, canals, and levees. Also, their wallowing muddies the water, which may adversely affect some fish species and reduce the growth of algae. Buffaloes commonly urinate and defecate in the water, possibly creating a pollution hazard, although in most situations this contamination is likely to be minor.
The presence of this herbivore in natural waterways may reduce the number of water plants. Some plants are trampled, some eaten, and some underwater species are suppressed because the muddied water transmits less light. This (and several other of the buffalo's environmental effects) can be turned to advantage (see picture page 85) when, as often occurs, aquatic plants grow out of control and become obnoxious weeds.
Damage to Pastures
Water buffaloes have very strong jaws, and when forage is sparse they graze it close to the ground; this overgrazing can destroy a pasture. In addition, they eat virtually all available plant material (including many species that cattle shun), so that a densely stocked pasture can become completely defoliated. In northern Australia it has been found that, with time, buffaloes become accustomed to a given pasture, and unless fences are strong they will instinctively return to it until the forage has been depleted.
The buffalo's inclination to eat many plants can be used to improve the environment and suppress growth of coarse weedy species of plants. On the Sepik Plains in Papua New Guinea buffaloes are being used to graze and suppress sedges (Cyperus species), as a result, the more desirable Paspalum species are beginning to appear. At Mount Bundy in northern Australia native pastures are being improved on a commercial scale by overstocking them with buffaloes. The animals reduce or completely eliminate spear grass and other weeds-even those with thorns-and thus foster the survival and growth of introduced forage legumes such as stylo (Stylosanthes guianensis). In Sri Lanka buffaloes have been used to graze out the vigorous tropical grass Imperata cylindrica.
Damage to Trees
Buffaloes instinctively rub against trees (and walls and fences), eagerly browse leaves, and sometimes nibble bark, so they damage trees more so than cattle. In northern Australia it has been noted that each "family herd" of feral buffaloes selects one or two trees for rubbing against so that the rubbing damage is confined to them.
Rajapske, G., 1950. Death of illuk. Ceylon Coconut Quarterly, 1:7-9.
Tulloch, D. G. 1969. Home range in feral water buffalo. Australian Journal of Zoology 17:143-152.
Tulloch, D. G. 1970. Seasonal movement and distribution of the sexes in the water buffaloes in the Northern Territory. Australian Journal of Zoology 18:399-414.
Tulloch, D. G. 1975. Buffalo in the northern swamplands. Proceedings III of the World Conference on Animal Production. Theme 1, Paper 7.
Tulloch, D. G. 1977. Some aspects of the ecology of the water buffalo in the Northern Territory. In: The Australian buffalo-a collection of papers, edited by B. D. Ford and D. G. Tulloch. Technical Bulletin No. 18, Department of the Northern Territory, Animal Industry and Agriculture Branch, Australian Government Printing Service, Canberra, Australia.