The Book of FrogsBy Tim HallidayUniversity of Chicago Press, 2016Frogs, the subject of Tim Halliday's glorious, magnificent new behemoth of a book from the University of Chicago Press, live all over Earth's land regions except in the cold centers of the poles. Their order, Anura, comprises over 7000 species and takes up over 80% of the whole roll-call of amphibians. They originated nearly 300 million years ago, colonized lakes, estuaries, marshes, and soggy soil all over a far more aquatic world, and filled the Paleozoic air with the raucous untuned symphony of their calls while dinosaurs ruled the land, sea, and sky. They survived the extinction of those dinosaurs and many other species so much more impressive than themselves, and they have been a part of human cultural life as long as humans have had a cultural life. The ancient Egyptians, seeing the rebirth of frog populations that always accompanied the flooding of the Nile, gave a frog's head to their goddess of fertility; in the Middle Ages, frogs were key ingredients in half the medical nostrums known to groping folk medicine; in the 1970s, a frog was one of the Western world's most popular entertainers. There are many senses in which something called The Book of Frogs could only be accused of overreach.Wisely, Halliday chooses to stick to the basics. His enormous book – a big, beautiful hardcover filled with color photos – follows a close-focused remit, giving a one-page snapshot of some 600 species of the world's frogs and quickly filling in the rough outlines of their distribution, life cycle, natural habitat, behavior, and conservation status.That last is particularly important; for the last 30 years, frogs have been making news headlines – for all the wrong reasons. At first mysteriously, and with increasing speed, frog numbers have been cratering, with dozens and dozens of species going extinct before field researchers were even agreed there was a systemic problem. Fossil records for such fleshy, delicate creatures are necessarily rare, but even so, it's safe to say more species of frogs have disappeared in the last 100 years than in the last 100 million years, and this ought to sound a very loud warning-claxon. Not just because frogs are marvels of Nature, although they are, and not just because the sudden disruption of anything previously stable is alarming, although it is, but mainly because of where frogs tend to squat in the larger picture of the ecologies.With a few dramatic exception (we'll get to them shortly), frogs are not only easy to eat but extremely smart to eat. They have no armor plating, no talons, no barbed tails. They can't fly or race away. And relative to their size, they tend to be packed with meat. They are blobs of easily-found, easily-caught protein; the once-familiar old stereotype of a trap consisting of a box propped up on a stick was invented for the poor dimwitted members of Anura. It's one of the reasons they tend to reproduce so effusively.The animal kingdom has always taken note. Frogs are utterly defenseless – and sinfully tasty – as tadpoles, and they aren't exactly stegosauruses as adults, with the result that they very often form an all-purpose delicatessen for the species around them. Just as a vast plant superstructure is supported by the mighty pollination efforts of the humble bee, so too a vast ecological buffet rests on the egregious edibility of the frog. A sudden, drastic drop-off in frogs is a sure bellwether of even more dire changes to come.Scientists have been strenuously researching that drop-off in order to determine in what precise ways mankind is to blame, and in the meantime, there is Halliday's book, with page after page of frog after frog in all their gooey, goggle-eyed glory.The Book of Frogs, produced by Ivy Press in the UK, features a frog on every page (some are called toads, but it turns out “the distinction between frogs and toads is biologically meaningless” – who knew?). There's a world map in the upper corner of each page, showing the distribution of the frog in question; there's a quick breakdown of the frog's adult and larval habitat and a note about its conservation status, ranging from “least concern” to “critically endangered;” there's a short description of the beast, a lovely black-and-white drawing of it by Sandra Pond, a close-up photo to highlight details, and, in the book's mesmerizing master stroke, there's also a life-sized photo of each frog, from the ones as small as your fingernail to the ones as big as a fat Guinea Pig. It's a stunning cavalcade, ranging from dull and knobby toads to tree frogs of almost translucent beauty, from very familiar and widespread frogs to rare and shy animals no humans other than researchers have ever seen in the wild (the Splendid Leaf Frog (Cruziohyla Calcarifer) of Central and South America, for example, glides between trees and spends all of its life in the upper canopies – you might distantly hear one while hiking far below, but you would never see one unless you went looking).The whole spectrum of frog success is covered here. There are species on the brink of extinction, like the critically-endangered Archey's Frog (Leiopelma Archeyi), which lives only in a couple of restricted areas on New Zealand's North Island, or the Booroolong Frog (Litoria Booroolongensis) in Australia, whose total population is confined entirely to an area of 4 square miles, or Starrett's Tree Frog (Isthmohyla Tica), which has all but disappeared since the early 1990s and may well be extinct. And there are unthreatened species, like the European Common Toad (Bufo Bufo) (we're told that “for most of the year, Common Toads lead solitary lives, hiding by day under logs, rocks, or rotting vegetation, and emerging at night to feed on insects and other invertebrates,” making them sound uncannily similar to editors-in-chief of literary journals), or the Green Toad (Bufotes Viridis), which is found all over Europe and, if molested or attacked, produces “an evil-smelling white secretion from their skin” (see above).Browsing through these pages and account after account of the life these frogs lead, you start to feel your old familiar image of a frog's life – sylvan, sedate, occasionally slippery – morph under the barrage of data, and the new picture that emerges is not only more vivid but surprisingly savage. Most frogs are highly territorial, and when their Irish is up after a strong rainfall or a moist warm season, the males are only too willing to fight with rivals (the females tend to be bigger – in the endangered Hispaniolan Giant Tree Frog – Osteopilus Vastus – they're fully twice as big). Rosenberg's Gladiator Frog (Hypsiboas Rosenbergi) is shown looking sweetly upward, fingers folded politely, and yet it's aptly named: those forelimbs contain sharp spines which can be released, Wolverine-style, when occasion demands: “This is normally withdrawn into a sheath but, during fights, it is unsheathed and is used to puncture the eyes or eardrums of the opponent.”Frog parenting can be similarly heartless. Species after species, especially in jungles and forests, offers their offspring no more of a head start in life than a short drop straight down into the nearest pond: slimy plops of eggs will be laid adhesively onto the undersides of branches, and the tadpoles hatch their way into a precipitous fall into the nearest source of water. And thing aren't a cozy nursery rhyme after that: the tadpoles of most frog species seem to be cannibalistic until they metamorphose into adults, a frog-eat-frog scenario that accurately presages the largely solitary lives most of thesespecies lead as adults.Solitary, except when the mating mojo strikes – then male frogs tend to congregate and vocalize. We associate a wide vocabulary of sounds with the frogs in our lives; their calls peep and pop and growl and boom through the twilight in countries all over the world during their mating seasons, when they throw all caution to the wind and raise a great song in quest of females to impress. People living on the East Coast of the United States, for instance, will associate the free-wheeling chorus of the Spring Peeper (Pseudacris Crucifer) with the beginning of Spring. “From a distance, choruses of males have been likened to distant sleigh bells,” Halliday tells us. “Within a chorus, adjacent males often form duets and trios, alternating their calls with one another.”These mass gatherings can make the collecting of frogs quite easy – some species easier than others, needless to say. Almost all frogs secrete an ooze from their skin as an aid to the hydration they require to stay alive, but not all oozes are created equal. Some are medical miracles, like the antimicrobial compounds that occur on the skin of Gunther's Frog (Hylarana Guentheri). Others are notorious, as in the case of the Golden Poison Frog (Phyllobates Terribilis), which Halliday informs us is probably the most poisonous known frog, with a venom strong enough to kill ten humans. Most poisonous frogs advertise that fact by festooning their skin with bright colors, although with all due deference to The Simpsons, untrained civilians are probably best advised not lick any frog they find in the wild, no matter how safe – and tempting – it might seem to do so.It's a joyous experience to savor the unbridled strangeness, the bursting profusion in The Book of Frogs, but as noted, it's sobering too. In Central America and eastern Australia – frog strongholds both – more and more species are succumbing to maladies like red-legged disease or chytridiomycosis, with entire populations being wiped out in some places. And all over the world, similar devastation is being wrought by pesticides, herbicides, habitat destruction, chemical fertilizers, and overhunting (whether it be for food, medicine, or the booming international pet trade). The number of frog species is increasing virtually every week as scientists penetrate every last nook of the natural world, but the number of actual frogs is decreasing at an equally steep rate, and it's no consolation for Halliday to point out that Earth's biodiversity just generally is in sharp decline – like most other species on Earth, frogs are losing their battle with the Anthropocene. It's depressing to think what the 2115 edition of Halliday's book will look like.But at least we have this edition, reveling as it does in some of the strangest and gaudiest of all Earth's great survivors.____Steve Donoghue is a writer and reader living in Boston. His reviews have appeared in The Washington Post, The National, The Wall Street Journal, The Boston Globe, and The Christian Science Monitor. He is the Managing Editor of Open Letters Monthly, and hosts one of its blogs, Stevereads.