Obituary;John Thorbjarnarson;

John Thorbjarnarson knew he could not end men's fear of crocodilians, hard-wired since hominids first ventured down from the trees into swamps that seethed with them. But in his 20-odd years working for the Wildlife Conservation Society he did more than anyone else to try. He commended the grace of their straight, silent swimming, their camouflage mottlings of yellow, grey and olive green, and the jewelled beauty of new, damp hatchlings no bigger than the span of his hand. He stressed their cultural importance, even magic: the dragon of China, bringer of good fortune, and the water god of ancient Egypt who made the grasses green. He extolled their niceness, snapping them as they basked companionably on warm mud or on a favourite bank of long grass, the forefoot of one embracing the back of another. Most crocodilians, he reminded people, preferred to dine on fish or molluscs rather than farmers. Most were sensitive, even shy.

He also warned the world how scarce they were. Before he began to catalogue them as a postgraduate, drawing up in 1988 an action plan to save them, all 23 species of crocodilians were threatened or declining. Their numbers had been destroyed by man's hatred and the handbag trade. Only a few years ago, exploring the Brazilian Amazon, Mr Thorbjarnarson found black cayman (“a very pretty creature, actually”) hunted indiscriminately, like fish. Patrolling the mouth of the Yangzi in 1997, where swamps had been turned into urban sprawl or rice fields, he counted only 120 Chinese alligators still in the wild. Here he began an intensive strategy of egg-collecting, captive rearing in the Bronx Zoo, and release. To his delight, the alligators from the Bronx remembered what to do.

Crocodilians, he explained, were much more like birds than snakes. They built nests he had to hunt for, poling his punt along sandbanks to find their holes or poking in the forest debris under the trees: a thin, laconic, clear-eyed figure as quiet and unobtrusive as the creatures he was trailing. He watched them brood their young, listening for the cheeps that announced the eggs were hatching and carrying the young to water. The Nile crocodile rolled its eggs gently in its teeth to help them hatch. In the WCS labs at the Bronx Zoo he would pull the papery, blood-pink shell from a hatchling and announce: “It's his birthday!” with a father's pride.

Massaging a cayman

Reptiles were never frightening to him, only fun. The little spectacled cayman, mysterious in its glass case in his boyhood bedroom, or so super-still, sitting on his head like a tiny allosaurus with its cool claws in his hair; the pet boa constrictor, in beautiful reticulated loops, swimming across the family pool; the snakes from the bog behind his house in suburban Norwood, New Jersey, where he would spend whole days squelching and hunting. He retained that obsessiveness and excitement, never growing out of them. His college thesis was on the spectacled cayman; he lived in Gainesville, Florida, where alligators sun on the paths; his favourite work involved drifting, by torchlight, in a silent punt among the vegetation mats of the Mamirauá in Brazil or the llanos of Venezuela, with crocodilians darkly all about him, or looping them up on a six-foot pole to take DNA samples from them and massage their scaly necks. It was while looking for dwarf cayman in Uganda in February that he seems to have contracted the malaria that killed him.

He had made a start on his rescue plans, but barely. Thanks to him, the Chinese alligator and the Orinoco crocodile were just beginning to recover; but the Siamese crocodile and the “amazing” slim-nosed gharial of India were still right on the edge. He struggled to persuade people who lived alongside crocodilians to see them not as pests, but as friends. He tried to train the locals to collect eggs carefully for a cash reward; to hunt and kill only adult males, under legal quotas, and leave the breeding females; to act as stewards of creatures that were precious and useful. Foreign governments usually supported him, but seldom produced much funding.

Primal fear, too, was hard to eradicate. When a farm duck was taken at night, or a swimmer disappeared, a crocodile or alligator would usually be blamed. In the popular mind they became huge beasts, invisibly inhabiting any murky stretch of water. Mr Thorbjarnarson would repeat that they were not like that. Most riverine accidents had nothing to do with them. And the only giant crocodile he knew of was the mythical kyunpatgyi, after which he was nicknamed by friends in Burma, which with the help of several beers could be seen swimming round a local island and surely with a smile.