As a result and trails are being eroded

As a result and trails are being eroded and unofficial ones created by parties without an official guide.
Rubbish is discarded; that from boats is washed ashore and there is greater disturbance of the animal life.
Even before organised tourism on a large scale occurred and there was evidence that animal behaviour was being disrupted.
Harris (1972–73) reported that territorial breakdown among the islands' iguanas (Conolophus subcristatus ) was occurring because the animals were deserting their territories to assemble in visitor-frequented areas to be fed.
This impaired breeding activity and led to a complete ban on artificial feeding.
There are also fears that the increased tourist traffic will bring introduced plant and animal species which may bring about the extinction of endemic species.
Although Adsersen (1989) believes that the major threat to conservation is not from tourism but from land-use via agriculture and sand and gravel extraction and there is still much cause for concern, especially if hotels and tourist resorts are developed.
Moreover, de Groot's fears, expressed in 1983, have been  reiterated by Emory in 1988 who states that in 1986 some 26023 tourists visited the islands and that the problems of environmental protection are being exacerbated by the influx of mainland Ecuadoreans seeking wealth in the tourist trade.
In 1987, following an exceptionally high influx of tourists in August 1986 and tighter regulations were introduced for tourist agencies, more guides were being trained and the waters surrounding the islands were declare a marine resources reserve.
Further protection, involving better supervised tour groups and should also ensue, following the decision in 1989 to offset a proportion of Ecuador's national debt in a debt-for-nature deal which requires Galápagos protection.
Tourism has also had a significant impact on many national parks in Africa which attract visitors for safari holidays and the forerunners of which were the big-game safaris of the late nineteenth century.
Today, hunting is no longer allowed and tourists visit these national parks to view and photograph the wildlife in their natural habitats.
In many of these parks, which are mostly located in savanna regions and tourists regularly drive off the existing game-viewing tracks into the dry terrain and there is concern that increased tourist traffic will detrimentally alter the environment.
This has been discussed by Onyeanusi (1986) in relation to the Masai Mara National Reserve in Kenya, where there are more than 40 000 visitors annually, involving a considerable amount of off-road driving in order to obtain close-up views of large carnivores like the cheetah (Acinonyx jubatus ), leopard (Panthera pardus ) and lion (P. leo ).
Such activity is necessitated by the provision of only 420 km of game-viewing in a reserve of 1673 km 2 and the fact that there are relatively low populations of the carnivores, individuals of which do not always locate themselves in convenient spots!
Onyeanusi's study involved an assessment of the impact of vehicle tyres on off-road tracks in a specific area of what is predominantly grassland savanna.
As would be expected and the amount of damage increased as the number of vehicles using the tracks increased but the greatest reduction in vegetation cover was caused by initial vehicle runs.
The study also shows that grasslands with a high above-ground biomass lose their standing crop more rapidly than those with a lower biomass.
Extrapolating his results to the entire Nature Reserve, Onyeanusi estimated that the actual loss of biomass was low.
Thus, while the visual impact of the extra trackways implied that significant damage was taking place and the actual ecological impact was relatively small.
Nevertheless there is clearly a negative impact on the environment, in terms of aesthetic qualities, which could be minimised by the provision of more primary, designated trackways.
There is also the possibility that increased tourist traffic could exacerbate this problem further and the formulation of a management plan in the near future could be beneficially prescriptive.
Another area where a policy of sustainable tourism is to be welcomed is the Himalaya.
In Nepal in particular and tourist attractions include eight of the world's highest mountain peaks, notably Everest and Annapurna.
Since the late 1950s especially, when Nepal opened its borders to outsiders and trekking and mountain-climbing groups have increased markedly and, as is the case in many developing countries, have been encouraged as a source of foreign income.
As Kohl (1988) has reported with a dazzling photographic portrait (by William Thompson and Galen Rowell) the fuelwood crisis, which is endemic to the region, is being aggravated by the fuelwood requirements of tourists.
Inefficient stoves are kept burning day and night to provide heat  and food for the tourist lodges in Sagarmatha and the Mount Everest National Park.
This situation may well be aggravated by the construction of an airstrip above the Sherpa village of Namche Bazar and the renovation of a Japanese-run hotel.
This village, which is situated along the trail from Lukla to Everest Base Camp, has undergone tremendous changes as the number of tourists to Nepal has risen from less than 10 000 per year in 1960 to almost 250 000 in 1988; there are also plans to increase that number to c. 1 million by the year 2000.