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.
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.