Monster, Myth or Lost Marsupial?
By Graham Joyner. Hayes UK and Thomas. $25.

Here are two very different books about searching for two very different types of "lost" animal. One is a global, coordinated and scientifically based search by scores of scientists for remaining individuals of 100 "disappeared" frogs of the numerous species whose populations have catastrophically crashed in recent years. The other is a meticulous one-man search through records seeking to confirm the existence of a mysterious creature – referred to variously as "yahoo" or "Australian gorilla" among other things – that purportedly lived until at least the late 19th century in our part of the world.

Moore is a professional wildlife photographer who, at the time of writing, was director of amphibian programs at Conservation International, a US-based NGO, though in his final powerfully argued chapter he seems to obliquely criticise their emphasis on "conservation for people's sake" and appears to be no longer involved with them. His book is a beautiful and unusual amalgam of well-explained science, passionate and reasoned advocacy, lyrical and evocative personal accounts (from childhood in Scotland to an emergency room bedside in Madrid to tropical rainforests at night) and handsome coffee table adornment. I love everything about it.

He skilfully sets the scene, building from his own involvement as an amphibian enthusiast since boyhood and moves on to describe the abrupt disappearance of whole frog communities across the globe from the 1980s on. One of the key strengths of the book is Moore's use of evocative stories from those who witnessed key events – including himself at times. He details succinctly the attempts to understand causes, which are still not totally understood, but which certainly centrally involve a skin-attacking chytrid fungus, interacting with climate change and habitat loss (though terrifyingly, many of the losses took place in pristine habitats). By 2010 at least 120 frog species were believed to be extinct, and that many again had not been seen in the last ten years; worse, nearly half of all species (some 3500 of them) were in serious danger of extinction. In the first decade of this millennium however, a few apparently extinct species made surprise reappearances, including the Golden Bell Frog in southern NSW.

These two facts led Moore to develop, in conjunction with the IUCN and under the auspices of Conservation International, a remarkable world-wide and widely publicised coordinated and targeted search for 100 frog and salamander species which had not been seen for at least 15 years. Thirty-three teams from 21 countries searched in remote and often damaged and dangerous places in Africa, Asia, the Americas and Australia. The book is the story of that research. Moore co-led teams to Colombia and Haiti and those stories are riveting, including night encounters with drunk teenage armed Colombian paramilitaries. The frogs are central to the story, but Moore is sharply empathetic to people and social issues, and his account of the environmental and cultural disaster that is Haiti is powerfully poignant.

In the event a remarkable 21 "lost" species were rediscovered, though all are at critically low levels; in addition new species were recorded. This is not a reason to relax, but it does mean that it's worth making efforts to protect what's left – all is not yet lost. The book concludes with a compelling chapter on our skewed views of what's worth protecting. Moore explains that most species-directed conservation money goes to just 80 species world-wide; most are large mammals, and none of them are any of the 3500 frog species poised on the brink of the precipice. It's not a reviewer's job to proselytise, but it is my job to urge you to read Moore's lucidly passionate discussion – and as a bonus you'll get some fabulous photos, especially of frogs but also of people and landscapes, and some excellent story-telling.

Joyner is equally passionate about his topic – he's been researching and writing on the one disputed animal for 45 years now – but his book isn't nearly as easy to read. In brief, he examines all available evidence from the 19th century on a series of reports from our general region on a supposed ape-like creature which he refers to as "yahoo" or "dulugal". (We are sternly warned in several places not to confuse the yahoo with the yowie, which apparently is a recent concept and utterly mythical.) He himself is entirely convinced that the yahoo existed, and indeed was a giant marsupial which surprisingly survived extinction until recently. The many rebuffs to his beliefs over the years however seem to have led him to a defensiveness throughout the book which contributes to the difficulty in reading.

An editor may have helped him eliminate this; a substantial number of words are dedicated to a sometimes turgid discussion of scientific philosophy in an attempt to discredit others' criticisms or simple lack of interest. Without a rigorous editor it is sometimes hard for a writer totally absorbed in his topic to be aware of the effect his absorption is having on his readers, though Joyner does actually suggest the entire chapter on possible etymologies of "yahoo" and "dulugal" "could, if considered too dense or obscure, be passed over by the reader". This is a brave and generous offer, but does not give one confidence; a better solution might to be to rewrite or omit such a chapter.

When I was young I pored over my father's copy of the mighty On the Track of Unknown Animals by Bernard Heuvelmans, reading the 700-odd pages two or three times – I am no enemy of cryptozoology. (Though I note that Joyner is offended that his book is catalogued by the Museum of Australia under that heading.) However Heuvelmans somehow made it all exciting and relevant and I'm afraid Joyner didn't achieve that for me, though maybe it was unfair to read this book after the previous one. That shouldn't stop you from reading it though if you're interested, and you certainly can't express an opinion on the yahoo without doing so.

* Ian Fraser is a local naturalist, broadcaster, natural history blogger and author, whose most recent book is Australian Bird Names; a complete guide.