Stranger in a Strange Land

An increasingly common aspect of globalization is the movement of plant and animal species to places that they did not previously inhabit. This movement includes plants sold for use in the horticultural and landscaping industries; birds, fish, and reptiles sold as pets; and stowaways on vehicles that carry goods internationally. A large number of these new populations will simply die out. Others will establish a viable population but will not raise an ecological or economic fuss. Yet another fraction will find much to like in their new home, and their numbers will swell and catch our attention. The species that will really stand out, however, are those that are numerous and also possess traits harmful to people, industry, or native biodiversity. It is these species that we call “invasive.”

Many articles and books have been written in the popular press during the past decade or so about the growing number of instances in which nonnative species become invasive. The questions that confront ecologists and society in general concern the degree to which we should worry about this change in species distribution; and if we should worry, what we ought to do about it.

In Out of Eden, journalist Alan Burdick examines these questions in the process of studying several cases of biological invasion. He starts with a trip to Guam to investigate the impact of the brown tree snake on that island’s native species and people; then proceeds to Hawaii, with its cornucopia of non-natives; and ends with a series of mini-excursions into the study of marine invaders. Along the way, he encounters scientists and citizens with varying interests in understanding the invasion of nonnative species. He uses these encounters to explore several principles related to invasion ecology and to reveal the daily life of invasion ecologists. Burdick’s overall mission is to discover for himself what the changing distribution of species means for his understating of nature.“Was this a new kind of Nature, or the old kind gone amok?” he writes. “What in this rapidly changing world is Nature?”

Before I pass judgment on whether Burdick achieves his goals, I should confess to my preference for reading about science, rather than reading science per se. I never pick up a book about science expecting to learn the complexities inherent in the scientific task at hand. I get enough of that at work. I like my popular science the way David Quammen delivers it, seasoned with laugh-out-loud humor. In fact, I think it takes a writer with a journalist’s sensibility to convey the wonder of nature that comes from the often backbreaking and tedious work of doing ecological research. Burdick’s book delivers the goods in this respect in a far better way than I had expected.

One of the features I liked about Burdick’s approach is that he goes well beyond the single viewpoint that all non-natives have negative effects and instead examines the changing perception of impact as the invader’s population grows and society responds in positive and negative ways. For example, Burdick took the time to read old newspaper accounts of the brown tree snake in Guam and found how difficult it is for societies to recognize the threat of invasive species. The brown tree snake has been an unqualified disaster for the people and native species of Guam. This Australasian native was introduced to Guam sometime after World War II, likely as a stowaway on military cargo. It is omnivorous and has thus managed to eat its way through a variety of native populations, including endemic passerine birds, driving some of the rarest species to extinction. It also bites a fair number of people every year (it is mildly poisonous), and it is responsible for frequent power outages. This has led to the development of elaborate and fascinating control and eradication efforts. Nevertheless, the early accounts of the snake by local journalists betray a lack of concern. Burdick quotes from a 1965 article in the Guam Daily News, written about 10 years after the snake’s initial release on the island: “Because they eat small pests and are not dangerous to man, they may be considered beneficial to the island.”

This view of invasive species is quite typical, even among invasion ecologists, because it is the nature of populations to increase slowly at first, even if the underlying dynamics herald an eventual explosion in numbers. Thus, even though some invasive species eventually cause serious ecological and economic harm, it is very difficult to decide whether the new species will turn into the evildoer you fear or the interesting new neighbor you can tolerate and perhaps enjoy.

Burdick also explores the perceptions of invasive species’ impact that are at the heart of how we relate to nature. Through interviews with citizens and biologists, Burdick documents an alarming disconnect between people and the natural world around them. Despite the average citizen’s interest in “wild” species, their curiosity is often quite satisfied through televised nature. This is the kind of nature in which lions interact peacefully with lambs and the wonder of the African Serengeti is only a channel-surf away. The end result is a kind of homogenized nature fantasy in which, Burdick writes, “every child dreams of crocodiles and lions at the expense of the bridled white-eyes and fruit bats in their backyard.”

Even if people do venture outside to interact with nature, they may find another barrier to perceiving the impact of non-native species. The more commerce serves to move species around, the more often the same set of species can be found everywhere. Burdick finds himself in exactly this situation when he flies to Hawaii “so eager to catch a glimpse of the unfamiliar Nature” and instead finds that he has succeeded “only in rediscovering my backyard.” Indeed, it is increasingly difficult to find a place far enough away from home, wherever that is, to see a big change in the set of species around you. This is one of the more subtle effects of the increasing prevalence of non-native species.

Good, bad, or both?

Burdick examines the conflicts that can arise between groups in society when an invasive species has both positive and negative aspects. He uses the example of a European pig introduced to Hawaii in the days of Captain James Cook. The pig was put on the island to provide later-arriving seamen with a source of meat. The pigs did quite well in Hawaii, and today can be found in forests on all the major islands. Those concerned with conserving Hawaii’s native plants and animals find the pigs problematic because they uproot native understory plants and create stagnant water bodies where invasive mosquitoes breed and then infest native birds with avian pox and malaria. Many native Hawaiians, however, rely on pigs as a source of dietary protein and consider hunting a part of their cultural heritage. The ensuing clashes between the two groups have sparked some interesting political fireworks. Burdick spends some time with Hawaiian hunters in order to understand their point of view and comes away with one of the more entertaining passages in the book: “Suffice to say, I had not been in Hawaii very long before I understood that the phrase alien species, used loosely and in the wrong company, might be hazardous to one’s health.”

Probably the most satisfying elements of Burdick’s book for me were his in-depth descriptions of ecological research and fascinating portraits of various invasion ecologists at work in the field. Burdick reveals the true nature of field ecology: dirty, tedious, and most certainly unsexy. I’ve encountered a lot of undergraduates whose knowledge of the ecologist’s life comes only from televised nature. I wish I could make them read this book and then come to me with ideas about what they would like to do for their senior thesis. We might get a little further a little faster.

I have two issues with Out of Eden that deserve some attention. First, I found a few factual mistakes that were understandable but distressing. For example, Burdick lists the Akohekohe, a Hawaiian honeycreeper, as extinct. Yet the bird is quite alive and kicking on Maui, although still threatened with extinction. Burdick likely used an older (mid-1980s) guide to the birds of Hawaii that erroneously considered the species extinct. This example and other such instances are not cause for great concern because none of the misstated facts play a key role in the arguments he is making. My second gripe is that Burdick occasionally overplays the metaphors he uses to describe complex ecological phenomena. Sometimes I found these metaphors charming and helpful. For example, Burdick compares the influence of non-native species on nutrient and carbon cycling through ecosystems with problems in finance and banking, with invasives “embezzling” and “laundering” ecological funds into foreign accounts that are held for use by non-native species only. On other occasions, I found myself grimacing a bit and quickly moving on.

Those faults aside, the achievement of Out of Eden lies in its multifaceted view of biological invasions. It covers a great deal of intellectual ground and does so in a compelling manner. I even laughed out loud a few times. Importantly, Burdick does not lose sight of his overall mission to search for what constitutes nature and how non-native species “fit” into this concept. This approach, I think, arms Burdick with a perspective that most recent writers on invasion ecology lack. He is not out to win you over to the side of “all nonnative species are bad” by reviewing how harmful some of them are for native species and societies. Instead, he seeks a more fundamental truth and has thus produced a fascinating review of how society and nature are entwined in today’s global community.

In keeping with this theme, Burdick does not end the book on what would be a probably false optimistic note. He instead takes us to the National Aeronautics and Space Administration’s (NASA’s) Jet Propulsion Laboratory in Pasadena, California, and introduces us to the prospect of exporting life to other planets. I had no idea that this was an issue, but Burdick provides another laugh for me in describing NASA’s past reliance on household cleaning methods in its efforts to keep microbes and other tiny life forms from shooting into space onboard one of its spacecraft; “The last thing Mars scientists want to discover is that Martians are the evolutionary descendants of Q-tips,” he writes. The realization of the Mars scientists’ nightmare may be nature’s last laugh as well.