SLIMBRIDGE, ENGLAND — `IN a way, I'm a simpleton - with one or two bright ideas that have ruled my life and which have not let me down.'' Sir Peter Scott does rather like to cut himself down to size. In the face of his achievements as elder statesman among naturalists, as founder-member of the World Wildlife Fund, founder of Britain's Wildfowl Trust, as president of various conservation groups, as highly popular naturalist-painter, as diarist, filmmaker, author, traveler-extraordinary, scuba diver - not to mention his Olympic bronze as a yachtsman in 1936 and his success as British gliding champion in 1963 - his self-assessment as ``simpleton'' does seem more than a little wide of the mark.
On the other hand, there is no doubt that this engaging man is a quite straightforward person, motivated by an uncomplicated fascination for wildlife which he has found a remarkable variety of ways to share with others. He is a popularizer.
At Slimbridge on the estuary of the River Severn he has, since 1946, set up a waterfowl reserve - with branches in other parts of Britain - that has the world's largest and most varied collection of waterfowl, wild and tame. It has proved to be enormously attractive to tourists, and equally successful as an educational resource.
Eighty this year, Sir Peter says as he chats in his studio, he still swims enthusiastically every morning in the pool his wife, Philippa, gave him, and although he discounts the rumor that - as one of the world's most devoted lovers and protectors of all kinds of waterfowl - he actually has webbed feet himself, he is shortly to leave on yet another of many coral-reef swimming vacations. He no longer scuba-dives, but, snorkeling on the surface, he observes and draws almost as much of the ``astonishingly rich ichthyofauna'' as before. ``In a good swim, in a hour, I would expect to get over a hundred species of fish.'' To him, fish are like ``underwater birds.''
Looking out of a vastly wide picture window over the home-made stretch of water nicknamed ``Swan Lake,'' which bursts with bird life, he still paints far into the night. His exhibitions in London are sellouts. His activities and energies remain prodigious - though in this interview he didn't mention his determination, expressed in his 1966 autobiography, ``to be the first octogenarian on the moon.''
For years, Sir Peter has been an effective campaigner for the cause of world conservation. His strongest tool is not public hand-wringing (though he's not against that, on occasion), but enjoyment. ``There's a lot of enjoyment in the world. ... I've always thought that one of the most wonderful human activities is going out and looking at nature. ... I like to do it with my water birds - and I get enormous pleasure from it. And a lot of other people do, too.
``That seems to me to be one of the basic things - that if you can get human beings sharing in enthusiasm, you can cross all kinds of difficult barriers.''
He's aware, of course, that different cultures make for such barriers, and that many countries in the world are far busier scrapping with their neighbors than giving the slightest thought to conservation. But just think what would happen, he argues, if the ``overlay'' of outrage that has surfaced because of Salman Rushdie's ``The Satanic Verses'' were instead channeled against humanity's destruction of the environment, pollution of the atmosphere, depredations on wild animals and plants. ``Then we would be getting somewhere!''
What he favors most are the sorts of organizations ``which come out of people's love of nature. ... I mean people who are enormously enthusiastic about butterflies and this kind of thing. ... This is terribly important, because this is coming out of love....''
Such organizations encourage people, he goes on, to ``get interested in the beauty of the thing, and then [they] begin to see the intricacy of it, and that begins to turn them into wanting to be scientific about it....''
He's realistic about the difficulty of interesting people at subsistence level in anything other than their own survival. But he doesn't believe that money should exclusively be funneled toward starving humans. ``I don't think it's an either-or situation. ... I mean, we've got to do both.'' Plants - tropical rain forests, for instance - are terribly important. ``This is what people have only just begun to realize, that global climate is what we're talking about. And global climate is going to be very decisive in whether our own species survives at all.''
He takes comfort in the fact that at last ``you're no longer regarded as the lunatic fringe'' if you talk about such concerns. ``For years, you know, nobody would listen.'' Now even the Conservatives in Britain (and, as one, he isn't proud of his party's record in this respect) show some signs of environmental concern.
HIS own campaigns have been both small and large. He is against the extinction of any species, period - from whales to mice, against extinction of even the smallest species. We simply don't know, sometimes, just how important to the ecosystem even the most insignificant creature is, he says. He has effectively rescued the Hawaiian goose from extinction by breeding it in captivity at Slimbridge.
On a larger scale, one thing he would like to be remembered for is his insistent proposal that the Antarctic become the first ``World Park.''
With its earlier family connections (his father was explorer Robert Falcon Scott, who lost his life in the Antarctic when Peter was 2), this part of the world has come to mean something very special to him. In his diaries he wrote: ``Imagine a continent as big as North America with one small town and a few scattered villages, most of them empty in winter.'' That's the Antarctic.
``Some pollution has already reached the Antarctic,'' he says, ``but not very much yet. And the Antarctic on the whole is pretty pristine.
``And of course it is also amazingly beautiful.''