"Wildlife," "natural," "wild" and "free" are terms that are loaded with meaning, redolent with atmosphere. They are words that may transport you mentally to the tundra, patrolled by polar bears, to the acacia-dotted African savanna across which herds of buffalo, gazelle, elephant and giraffe roam, or to the cathedral stillness of a Borneo rain forest, where gibbons hoot their dawn chorus and great orange apes move methodically in four-limbed brachiation. "Wildlife," "natural," "wild" and "free" are words that, for me, conjure up everything that is not tamed, domesticated, trapped or tethered by man.

Yet that is something of a romantic dream these days, so widespread is our human (though often inhumane) influence. Whatever those words conjure up for you, they are likely to suggest something far removed from the increasingly urbanized human environment that more than half of us live in.

I traveled recently with an octogenarian, during whose lifetime the human population has grown from less than 2 billion to more than 6 billion. During that same lifetime what was once wild has steadily disappeared, traded in for agriculture, development and urban sprawl. It is not just that wild populations or even species have disappeared, but that the very places where they used to live have been overwhelmed and obliterated.

Yet even as our population expands, an increasing number of people are seeking solace and relief from their busy, crowded lives by taking time out in "nature," or in what they believe is "nature." For many, just knowing that there is something natural "out there" is something of a relief.

The ecotourism business is dependent on this urge to experience what remains of our natural world. Lest you think that this type of travel is limited to a special few, consider that many individual national parks around the world now receive more than a million visitors each year, while some top 3 million. The global movement of ecotourists can certainly be counted in tens if not hundreds of millions of people.

Those people long to experience nature, even if only for a brief part of their year, and a huge industry is growing to serve their needs, but who is regulating the service? Who is there to say, exactly, what is wild, natural or free? Who is there to ensure that the very places ecotourists are attracted to remain wild or natural?

In reality, ecotourists are consumers of a service that they must take on trust. The people providing that service, which is dependent on places such as national parks or national nature reserves managed by government departments, are usually highly motivated and dedicated naturalists, sometimes even scientists.

An increasing number of private consortia, however, realize that the lands surrounding such parks and reserves are ideal places to establish private reserves catering to ecotourism. This is not a bad thing, as it increases the area of land receiving some degree of protection from development, and in some cases creates what amounts to a buffer zone around the original reserves.

These private areas are found under different names: game reserve, game park, game lodge, hunting lodge and so on, depending on their location and their purpose. Their aim is to show visitors wildlife, so many are fenced to keep the wildlife in and visible.

As development, agricultural or urban, spreads, nature retreats. As nature retreats, natural areas around the world become islands of natural habitat in a sea of development. Many of these islands of habitat are, in fact, fenced. The fences keep animals in the "natural" areas and out of the human areas.

It is an interesting concept, isn't it, nature fenced in. Humans fenced in would consider themselves within a prison. When I was growing up in rural England, much of "nature" was already restricted to nature reserves.

Nevertheless, I recall a childish dislike of safari parks. Safari parks seem merely an extension of the zoo concept, where the land area is larger, the animals have more room in which to roam and a number of species, minus their predators, are allowed to mix. Zoos are not my favorite places; after all, most are merely prisons for animals where the visitors are not relatives, but gawking humans.

Admittedly, from the individual animal's perspective life in a safari park is better than in a zoo. It is, however, still confined, and so the safari park is merely an open prison. While the species are what we might call wild (i.e. not domesticated), and while some of the animals may have been born in the wild and then captured, they can not by any stretch of the imagination be considered to be "living wild" while within a safari park.

The distinction between a safari park and the wild is an easy one to grasp in Europe or America. After all, the species in the safari parks are not indigenous, being African animals. Visitors are immediately aware, no matter how attractive the surroundings are, that what they are seeing is a collection of captive animals in what is for them an unnatural setting. It sounds contradictory to say it, but although they are "wild animals," they are not "wild."

Perhaps at this point I should clarify what I mean by wild. "Wild" implies that an indigenous animal is living free, as part of a free population, in a region where the species has arisen without human intervention. This is a complex way of avoiding the circular argument of saying that wild animals are animals that live naturally.

Translate the safari park concept to Africa, though, and what you have is much more ambiguous. After all, the animals may be indigenous to that part of Africa, they may have even been born in the wild, but they have been moved to a particular area for commercial reasons.

Imagine another scenario. A national park has been designated in an area of natural habitat, but unfortunately some of the species originally there were exterminated by hunters some decades ago. With changes in attitude, it is now practical and reasonable to reintroduce such species from other areas. So while the gazelles in the national park may be wild, the cheetah that now preys on them may have been reintroduced, returned to the wild, in a wild area from which it had disappeared.

Such places exist. The reintroduction of species that have disappeared from an area is now a frequent part of conservation or ecological restoration activity. The purpose is clearly nature conservation.

Elsewhere, private land that was once used for farming has been allowed to revert to natural bush or grassland, but all larger wild animals are absent. All have to be imported or reintroduced from the wild, and so economic justification comes into play.

The rub now is that when one sees a creature roaming an apparently natural area, it is almost impossible to know if it is truly wild, creating a moral dilemma for ecotourists, who are motivated by "nature," and the companies serving their needs, who are motivated by economics.