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BOOK REVIEW

It's Not Easy Being Green

Simon Stuart

Amphibian Declines: The Conservation Status of United States Species. Edited by Michael Lannoo. xxii + 1,094 pp. University of California Press, 2005. $95.

Until the late 1980s, scientists lumped the fate of amphibians with that of other wildlife species. As long as we could conserve habitats in sufficient quantities, the reasoning went, we could conserve the creatures that depended on them. But then investigators began to make a puzzling observation. Even in places that were seemingly pristine, amphibian populations were mysteriously declining, some to the point of disappearing. This phenomenon was not limited to just a few species or a small geographic area: Losses have been documented in Australia; in North, Central and South America; in the Caribbean; and more recently in Africa and Asia. In Latin America alone, nine families and 30 genera of amphibians had been affected by the late 1990s.

At first, some scientists were skeptical that the decreases were real, because amphibian populations are notorious for fluctuating widely. Once powerful statistical tests showed that the declines were far more widespread than would reasonably be expected by chance, most researchers eventually agreed that something was seriously amiss. Reports of declines and extinctions accelerated during the 1990s, and the mass media latched onto the story. These observations indicated that something specific and troubling was happening to amphibians. At one locale in Costa Rica, 40 percent of the amphibian fauna disappeared over a short period in the late 1980s. Similar stories can be told about other sites. The loss of amphibian species not only contributes to the world's biodiversity crisis but also has important implications for the ecosystems where the declines occur. Without amphibians, links in food webs are broken, and other organisms suffer in often unpredictable ways.

This tiny Pacific tree frog...Click to Enlarge Image

Although some of the earliest, perhaps the earliest, amphibian declines were recorded in the United States, much of the scientific literature focuses on decreases in tropical countries, where losses have often been more dramatic and have certainly involved larger numbers of species. This has led to the curious problem of declines in temperate amphibian species receiving insufficient attention. Michael Lannoo's long-awaited magnum opus Amphibian Declines is the first focused attempt to pull together all the information from the United States and thus provides a much-needed weight to correct the imbalance.

Lannoo's book is a massive undertaking. The 215 contributors amount to a who's who of U.S. herpetology. The volume falls into two main parts: There are 350 pages of "Conservation Essays" and 575 pages of "Species Accounts."

The exceptionally diverse essays found in Part One are divided into seven sections. The first provides an introduction, giving a global context for what is happening to amphibians; it includes an essay on some philosophical issues. This section is followed by one on declines, which starts with an overview of an interdisciplinary research program funded by the National Science Foundation, followed by a look at the biology involved. Of particular interest is a chapter by Richard Highton detailing losses in eastern North American woodland salamanders since 1985. These declines are of significance, because these species have not for the most part been a previous focus of concern. There are also two chapters on Northern cricket frogs.

A long section on causes contains 12 essays covering global change, habitat loss, ultraviolet radiation, pollutants, various diseases and commercial trade in amphibians. The next section consists of 18 essays on conservation, some of which focus on particular species (such as the Houston toad, the Western toad and the spring and cave salamanders of Texas) and others of which deal with a very diverse set of general issues. Examples include essays on habitat reserves for migrating salamanders, critical areas for conservation, landscape ecology, population manipulations, exotic species and the protection of amphibians while restoring fish populations.

There are nine essays in the section on surveys and monitoring, including some that are about particular projects and others on general techniques (such as evaluating surveys based on frog calls, using geographic information systems and taking advantage of data in museum collections). The section on education is less comprehensive, with just two articles—one on the National Amphibian Conservation Center at the Detroit Zoo and the other on the Minnesota initiative "A Thousand Friends of Frogs." An evocative piece from the perspective of William Souder, titled "Of Men and Deformed Frogs: A Journalist's Lament," rounds off Part One.

This collection of essays would make an impressive book on its own, but the real meat is yet to come. Part Two gives an accounting of all 289 amphibian species in the United States: 103 species of frogs and 186 species of salamanders. Lannoo, Alisa L. Gallant, Priya Nanjappa, Laura Blackburn and Russell Hendricks have provided a 16-page introduction to these species accounts, explaining the methodology, database design and map development. They present an interesting analysis of the patterns of species richness across the United States, first considering all amphibians, next frogs and then salamanders. They also have maps of species categorized according to their breeding strategies.

The exceptional importance of the United States for salamanders is clear: It has more than 35 percent of the world's described species, a greater proportion than any other country in the world, with the Southern Appalachian mountains constituting the global center of diversity. The United States has two endemic salamander families, the amphiumas of the lowland Southeast and the torrent salamanders of the Pacific Northwest, with two other almost-endemic families, the sirens and the Pacific giant salamanders. By contrast, U.S. frogs are relatively less unusual, although mention must be made of the tailed frogs of the Northwest, which together with the New Zealand frogs are the most primitive of all extant anurans (frogs and toads).

The species accounts are monumental. They bring together a vast amount of information, some of it previously unpublished and much of it formerly inaccessible to most people. Each account has four main sections: historical versus current distribution (including a distribution map); historical versus current abundance; life history features (breeding, eggs, larvae, habitat, range, territories, size, longevity, feeding behavior, predators, diseases and so forth); and conservation status. Anyone desiring an up-to-date and comprehensive overview of any amphibian species in the United States will want to use these accounts.

A 20-page epilogue by David F. Bradford examines the factors implicated in U.S. declines, teasing out how these affect different taxonomic and regional groupings of amphibians. Habitat loss in general is the overriding threat, but significant declines have also been attributed to invasive species, chemical pollutants and disease.

I have no hesitation in recommending this book to anyone interested in conserving U.S. amphibians. Lannoo deserves many congratulations for his leadership in seeing this enormous project through to completion and for making the results available in such comprehensive form.

I have only a few criticisms, two of which relate to the distribution maps. First, all of the species have unfortunately been mapped according to their presence or absence in counties (or in smaller units in parts of the West where counties are sometimes very large). This coarseness has the effect of overrepresenting the ranges of very narrowly distributed species (the Jemez Mountain salamander, for example) and in any case results in the maps being a less precise reflection of current knowledge than the collective inputs of the 215 contributors surely must have made possible. Second, the pale gray used for the maps makes them hard to decipher in many instances. It is a great shame that it was not possible to present the maps in color and to show former as well as current ranges. Readers who want to see the maps more clearly, and in color, may visit http://www.pwrc.usgs.gov/armiatlas/.

Another complaint is that, despite presenting wonderfully detailed data and including a useful analysis of the differing levels of impact that various causal factors have had, the book fails to provide a good overall picture of the status of U.S. amphibians. That's a shame. Existing country-wide analyses are either becoming slightly dated (Precious Heritage: The Status of Biodiversity in the United States, edited by Bruce A. Stein, Lynn S. Kutner and Jonathan S. Adams, was published in 2000) or form part of larger regional analyses (for example, the 2004 book Disappearing Jewels: The Status of New World Amphibians, by Bruce E. Young, myself and others). So a good, up-to-date summary of the state of amphibian affairs in the United States is sorely needed and can certainly be written on the basis of the data in Amphibian Declines.

My final, smaller complaint about this compendium is that the IUCN Red List categories, which are measures of relative extinction risk, are not provided for each species. Their absence might be a reflection of the fact that IUCN's assessment of the world's amphibians was not completed until October 2004. However, it would have been possible to use the broadly similar NatureServe global rankings. According to IUCN, 51 amphibian species in the United States (17 percent of the total) are globally threatened. This is much less than the 32 percent global average, but still worryingly high for a country that has had the resources to implement conservation programs.

However, these shortcomings are minor compared with the very many positive aspects of the book. It is a magnificent achievement that sets a standard for the rest of the world to follow.


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