Book Review: The Wolf's Tooth

I love a good story. Someone can stand up at a conference, give a talk largely unsupported by data and lacking even the remotest truth, but if they do a good job relaying a story to me, well, I'm hooked. That's my vice. So it should come as no surprise that as a canid biologist, the theory of trophic cascades -- the focus of conservation biologist Cristina Eisenberg's new book, The Wolf's Tooth -- very much appeals to my love of a good story.

Trophic cascade theory would say that wolves reintroduced into Rocky Mountain ecosystems would reduce elk numbers and alter elk behavior thereby changing the plant communities elk feed upon, with the other animals that depend on these plant communities -- say, beavers, amphibians and songbirds -- ultimately benefiting. Eisenberg argues that by maintaining large predators at the top of the food chain the trickle down effects of their presence reverberate throughout an entire ecosystem. What a beautiful, humbling concept.

Eisenberg's book is quite timely. Two weeks ago a federal judge restored Endangered Species Act protections for wolves in the U.S. northern Rocky Mountains, after the government delisted wolves in Montana and Idaho in April 2009. The debate over wolves and whether they have a rightful place in today's western landscape rages on among wolf advocates, hunters, and ranchers. At times it seems everyone who lives in the West has an opinion about wolves. But this debate is not new. Wolves have been making their way back to Montana via Canada since the late 70's and all the arguments, depositions and website rants will never reach the upright ears of those wolves living high in the mountains. To Eisenberg, those wolves are busy doing what they do -- restructuring ecosystems by preying on abundant, and sometimes overly abundant, ungulates.

Outside of the debate raging within science over the reintroduced wolves of the northern Rockies is a spectrum where wolf advocates, on one end, tend to believe that a landscape where wolves are present is "balanced" and the effect of that animal is positive on all life forms sharing the landscape with it. On the opposite end of this stereotyped spectrum are some hunters, outfitters, and ranchers who view a landscape containing endangered wolves as one completely "out of balance" and in need of intense management. Eisenberg's book will not likely solve any of these debates or convert anyone to a different frontline, but The Wolf's Tooth certainly brings a wealth of information to the table about the potential effects wolves can have on ecosystems.

Eisenberg compiles the mountain of evidence supporting trophic cascade theory into one volume that's easily digestible by scientists and non-scientists alike. The Wolf's Tooth is largely devoid of pictures, figures, and (quite refreshingly) tables of data. Much of the book is spent relaying a compelling amount of trophic cascade research and work demonstrating its ubiquity in a variety of ecosystems from land to sea. While an intricate look at trophic cascade research is welcomed in the face of the controversy swirling around the ecological effects of wolf reintroduction, highlighting study after study ends up reading a bit dry in places.

At her most engaging Eisenberg interweaves her own experiences and passions into the larger picture of trophic cascades and food webs. For example, while studying an old-growth forest she "wonder[s] how science can do justice to this complex, ancient community" and poetically muses that "[y]ear by year the data accumulate, like leaf litter on the forest floor, each observation contributing to the whole of our knowing, helping us to redefine who we are in relation to the world". These passages strike at the heart of what it means to be a biologist.

While I enjoyed the periodic anecdotes about Eisenberg's own research with wolves and trophic cascades, I think The Wolf's Tooth would have benefited from the author discussing in more detail her own research findings. This would have given Eisenberg the venue to merge personal experience with science creating a more engaging and interesting text instead of periodic glimpses into her own work followed by lengthy descriptions and citing the trophic cascade research of others. Eisenberg could have burrowed into her own results more and shown clear evidence of trophic cascades as a result of wolves' presence while blending in her own, often quite vivid, personal stories of doing field studies in the wild.

Later chapters of the book discuss how the science of trophic cascades can be used to inform natural resource management and land conservation. Eisenberg gives a wonderful example of how trophic cascade principles have been used to adjust fishing quotas and how the effects trickled down, affected algae blooms, and ultimately enhanced water quality on Lake Mendota, Wisconsin. In spite of this real-world example along with others that the author presents, much debate persists about the strength and predictability of terrestrial trophic cascades.

Eisenberg does address this contention when discussing trophic cascades and resource management but writes that, "...it is important for policy-makers to move beyond [the arguments] and begin to apply trophic cascades principles to conservation and natural resources management." I am sure some will be irked by the short shrift she gives to this fierce debate, and I'm certain some will be equally incensed at Eisenberg's call to forge ahead with a management directive rooted in trophic cascades principles in spite of the unsettled dust still blowing about the scientific arena with regard to wolves.

A bit of a misnomer, The Wolf's Tooth is less about wolves and teeth than it is about trophic cascades in a suite of ecosystems. While in spots I found the book a bit dry, I appreciated the broad view and impressive amount of research, in the field and in the library, Eisenberg has done on this topic. Rich in documentation, peppered with personal stories and clearly (particularly the final chapters) infused with Eisenberg's passion for the natural world, The Wolf's Tooth is a solid summary of trophic cascades research and theory up to the present.

The Wolf's Tooth: Keystone Predators, Trophic Cascades, and Biodiversity, by Cristina Eisenberg, Island Press, Washington DC, 2010. 320 pp. ISBN: 978-1-597-26397-9. $35.00.

David Ausband is a research associate at the Montana Cooperative Wildlife Research Unit housed at the University of Montana in Missoula. He regularly radio-collars, tracks and studies reintroduced wolves in the northern Rocky Mountains.

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