Diversity

Authors: Jim Labisco and Richard Griffiths. Publishers: Princeton University Press
2025; 288 pp, hardback, ISBN 978-0-691-25501-9, £30.


Roger Downie, Froglife and University of Glasgow

Princeton University Press is well-known for its series of lavishly-illustrated WildGuides to the biodiversity of Britain and Europe. This book is not in that series, but is a similarly beautiful ‘introduction’ to and ‘celebration’ of the diversity and lives of frogs. The authors are Jim Labisco, a young lecturer at University College London and not-so-young Richard Griffiths, emeritus professor at the University of Kent and one of the UK’s most eminent herpetologists. In addition, the production team at Princeton University Press, acknowledged at the end, are responsible for much of the arrangement of the book, and such decisions as the use of American rather than British English, and the inclusion of imperial as well as metric measures.

The book is in hardback, 288 pages long and listed at £30: what do you get for your money? First, a lot of beautiful colour photographs of frogs. As an example, the 12-page introductory chapter is more than 50% illustrations, including three full page photographs. Following the introduction, which summarises frog diversity and tackles the age-old question (what’s the difference between frogs and toads?), nine chapters cover different aspects of frog biology: evolutionary origins; life on land and in freshwater; communication and reproduction; development and parental care; activity; nutrition; defences against predators and disease; population fluctuations; and, finally, the frog population decline crisis and what is being done about it. At the end of each chapter, there is a set of five species accounts, with a full-page photograph and a page of text describing the species, its distribution and key features. The species are chosen to illustrate some aspect of the preceding chapter. For example, the Lesser Antillean Frog Eleutherodactylus johnstonei  which likely originated on the Caribbean island of Montserrat and has now spread throughout the region (largely by anthropogenic means), is used to illustrate the chapter on frog movements. I have had some involvement in documenting its spread in Trinidad and Tobago. Each account includes a world map in grey, showing the frog’s distribution in green (oddly missing for E. johnstonei). Following the topic chapters, there’s a glossary defining some technical terms, a list of resources and an index.

The book has high production standards. Each photograph has a clear legend including an arrow pointing to the illustration (rather than a figure number). In addition to photographs, there are many other graphics: I particularly liked the two-page  illustration of the frogs inhabiting an Amazonian floating meadow (pp. 56-7). Sources of original illustrations are given in the end acknowledgements section, but in a very concentrated format: I would personally have preferred them in the figure legends. Frog names are mostly given as capitalized common names and italicised scientific names, although scientific names are omitted from some of the graphics. I found very few typographical errors. One minor problem: the text includes frequent  cross-references to pages where more information on a topic can be found; some of these are to chapter numbers, but the contents page does not number the chapters, and you need to work out for yourself that the introductory chapter is not counted as chapter one.

Who is the book aimed at? An ‘introduction’  might seem to be for people who don’t already know much about frogs, but who would like to find out, or for people who know about their local frogs, but not about any others. The book’s coverage is very wide-ranging, quite detailed, pretty up to date and mostly uses non-technical language, so there is something here even for people who know quite a lot already. For example, the truly viviparous African frog Nimbaphrynoides occidentalis was new to me, as were the Brazilian frogs whose bony spines on the skull allow them to inject toxins into attackers, making them the only truly venomous frogs. I do however have some grumbles and reservations:

The description of North American frogs that survive extremely cold winters claims that their blood contains anti-freeze proteins. The research I’ve read denies this: rather, these frogs tolerate freezing by greatly increasing circulating levels of glucose which acts as a cryoprotectant, preventing damage to frozen cells.

About frogs that develop directly to froglets, without a tadpole stage in water, we read that ‘tadpoles complete their development within the egg capsule and hatch as fully metamorphosed froglets’. There is a wide range of direct developing frogs, but at least in those I have looked at, it is misleading to think of the early stages as tadpoles, because they are so highly modified, with the tail bud developing into a hugely expanded respiratory organ.

There are some examples of what I call inappropriate ‘speciesist’ writing, where a trait is said to have evolved in a particular species, but where it is actually characteristic of a whole group, genus or family. Examples are the occurrence of disc-shaped suckers in torrent-dwelling tadpoles (this is a feature of the multi-species genus Amolops, not of a single species); and the lack of a tongue in the Surinam Toad is, again, a feature of pipids in general.

It is claimed that Cane Toads locate Tungara Frogs (as prey) by detecting their calls. I’d like to see the evidence for this. Michael Ryan’s work showed that predatory bats locate Tungara Frogs by their calls, and that the frogs simplify their calls when bats are present, increasing their survival chances, but at the cost of reducing mating opportunities, because females prefer the complex calls.

I also felt that there are some odd omissions or example choices. Variable tadpole morphology in response to environmental factors (polyphenism) is exemplified by Mallorcan Midwife Toads, but not by David Pfennig’s stunning description of the carnivore/omnivore morph system in spadefoot toads. Salt tolerance is mentioned in the American Green Treefrog, but the best known and most complete example of this, the Crab-eating Frog Fejervarya cancrivora is surprisingly omitted. Similarly, there is a brief mention of one treefrog species reducing water loss by means of mucus skin secretions, but the fascinating skin-wiping behaviour, spreading a waxy secretion over the skin in phyllomedusine frogs is absent. The farming of frogs as a source of human food is briefly mentioned, but the conditions under which these frogs live and are slaughtered is not discussed: the welfare of frogs remains a little considered subject.

Next, a frustration. The text omits citations to sources, so how can you follow up on points of interest? The book list is a good resource (although, outrageously, Altig and McDiarmid’s seminal Tadpoles is omitted), but only two of the books were published after 2015. You can find some of the examples in the ‘selected’ list of research papers, but without clear citations, it is a labour, and for the general reader the book is aimed at, not used to working through research papers, quite intimidating.

The final chapter appropriately covers the worldwide decline in amphibian populations, reviewing causes (I feel that herpetologists have yet to factor in the likely links with the parallel declines in insect populations) and progress towards solutions, both small-scale community-based work  such as Toads on Roads campaigns, and large-scale efforts such as the Amphibian Ark, which focuses on the captive breeding of threatened species. I was surprised not to see any comment on such efforts to save Darwin’s Frog and the Mountain Chicken (both are covered under the parental care section, but with no comment on their dire state in the wild). The list of organisations at the end includes many of the organisations involved in frog conservation, but oddly omits Froglife (responsible for Toads on Roads in the UK) and Save the Frogs. In conclusion, despite the reservations listed above, I thoroughly recommend this book. It truly is a celebration of frog diversity, and I endorse the message at the start that the main motivation behind conservation efforts should not be based on notions of services frogs may provide to us, but simply because they are wonderful.