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MONTH: October 2007

How adaptive species became "invasive"
Commentary by Merritt Clifton

"Exotic species," "alien species," and "invasive species" are semi-synonymous terms which to most people may seem insignificantly different.

Each is a metaphor for species not indigenous to their habitat: non-native species, to introduce yet another term, less rich in connotation.

Yet obscure as the distinctions among "exotic," "alien," and "invasive" species may be, the terms are different enough to have inspired environmental advocacy groups and government agencies to spend millions of dollars in recent years to bring first "alien" and then "invasive" into vogue.

Behind the linguistic politics is the belief that terminology tends to shape attitudes. Thus, at about the same time that the Natural Resources Defense Council began banging the drums about "invasive" species, In Defense of Animals began to push use of the term "guardian" rather than "owner" to describe a person who keeps a pet.

However, while In Defense of Animals sought from the beginning of the "guardian" campaign to change the language of laws, the NRDC and others pushing alarm about "invasive" species merely introduced their preferred terminology into public discourse. The idea was to increase support for existing policies and programs against non-native species, not to turn government in a different direction.

Indifferent and often even favorably disposed toward "exotic" species, the public was believed likely to become more concerned about "alien" species, and most likely to view "invasive" species as a threat.

What's in a name?

Dave Poulson, associate director of the Knight Center for Environmental Journalism at Michigan State University, maintains an online glossary of environmental terms. A careful lexicographer, Poulson recently asked fellow members of the Society of Environmental Journalists to help him distinguish the differing shades of meaning among "exotic species," "alien species," and "invasive species," as used in news coverage.

Doug O'Harra of Far North Science, in Anchorage, Alaska, offered distinctive definitions which might not withstand all critical scrutiny, but were accepted by the discussion participants as accurately reflecting most contemporary newsroom use.

An "exotic species," O'Harra pronounced, is any species living somewhere other than where it originated.

An "alien species," O'Harra opined, is an exotic species which was deliberately introduced to non-native habitat.

Neither exotic nor alien species "necessarily threaten the local ecology," O'Harra stipulated, but an "invasive species" in his opinion "threatens the ecology of a local habitat by out-competing or killing off native species--usually because the native species lack defense mechanisms, "or because the alien/invasive species no longer faces the predators or parasites that held it in balance in the species' original habitat."

This is more-or-less what is usually taught in biology classes, nature center visitor lectures, and wildlife documentaries, but as ANIMAL PEOPLE pointed out, O'Harra's summary misses a key component of the process by which "exotic" or "alien" species become allegedly "invasive."

Typically, the ecology of the habitat has already been transformed by climate change, cultivation, deforestation, drought, volcanic eruption, or other events that take away the survival advantages evolved by the native species through natural selection. Whatever the native species came to do, that helped them in the habitat of long ago, is no longer advantageous.

For example, shallow-burrowing native marsupials in Australia lost much of their habitat to the introduction of sheep. The sheep compacted the soil, ate the native plants, monopolized the water, and were attended by bored shepherds who often amused themselves by killing wildlife. The brushy dry forests of pre-settlement times, burned to make pasture, gave way to desert.

Eurasian rabbits, who evolved with sheep, were enabled to take over huge swaths of habitat, along with rabbit predators including feral cats and foxes. Each moved into habitat niches which had been made more favorable to them than to the extirpated marsupials.

Thylacenes, of "tasmanian tigers," also called 'Tasmanian wolves," evolved to hunt marsupials in the dry forest. They crashed toward extinction, and probably would have drastically declined anyway, even if they had not been persecuted as suspected sheep predators, because their habitat was radically altered and their prey base was reduced. Thylacenes had persisted for about 8,000 years in competition with dingoes, who arrived with the first humans in Australia, but the coming of sheep irrevocably tipped the balance. Dingo ancestors had hunted rabbits--and sheep--in Asia. They rapidly made the transition back to a rabbit-based diet, eating sheep too when they could, and took over the habitat that thylacenes could no longer hold.

When the adaptive success of "invasive species" to altered habitat is understood in context, the insidious implications of the term "invasive" become much more visible.

Invasive language

The history of the phrase "invasive species" is illustrative of a linguistic parallel to the evolutionary process of how species become "invasive," demonstrating how a misguided belief can wreak havoc when the cultural climate favors it, no matter how wrong it is. "Invasive species" is actually of surprisingly recent origin in common use, and despite years of deliberate effort to introduce it, it only gained currency when the U.S. "cultural ecology" changed abruptly in 2001.

Tracing the rise of the "invasive species" issue, ANIMAL PEOPLE ran keyword searches of 1,428 U.S. newspapers indexed 1976-2006 at <www.NewsLib-rary.com>. We proportionally weighted the findings to compensate for the rising frequency with which newspaper content was filed electronically during the 30-year sampling.

Before 2002, the relatively neutral term "exotic species" was the most commonly used collective term for non-native animals and plants. No other term was even commonly used until 1999. The word "exotic" is most often associated with "different," "unusual," or even "erotic." The positive associations of "exotic" long frustrated ecological nativists, whose environmental philosophy evolved in the 19th century parallel to political nativism.

The basic idea behind both strains of nativism is that whatever existed in a particular place at a specific time chosen by the power-holders belongs there, while new arrivals are a threat. Both strains of nativism have waxed and waned repeatedly in influence, tending to gain strength whenever and wherever the dominant culture is challenged by immigration.

For example, California in the 1930s could not legally bar Dustbowl refugees from entering the state, but it could and did set up checkpoints at the state borders to minutely inspect immigrants lest they carry produce that might harbor insect pests.

Ecological nativists sought mostly unsuccessfully until recent years to rally support for eradicating popular animals whom they perceived as threats to their own favored species, and often debatably termed "non-native" as a pretext for extermination.

Time and again, nativists were rebuffed--for example, in seeking to kill mute swans to expand trumpeter swan habitat, cutthroat trout blamed for depleting native trout in Lake Yellowstone, and mountain goats who were accused of eating rare alpine flowers in Olympic National Park.

Nativist purges of hooved species from the Channel Islands and of feral cats from many locations were waged mostly against public opinion, and were often possible only when privately funded organizations such as The Nature Conservancy bought the land to be purged, then did the killing before turning the land over to the U.S. or state governments.

The public has generally supported campaigns against the likes of the lake weed Eurasian watermilfoil, lampreys, zebra mussels, and gypsy moths, but even these efforts have been stalled at times by concern rising ever since Rachel Carson published Silent Spring in 1963 that the chemicals used to kill so-called pests may be more harmful, in many instances, than the target animals and plants.

For decades wildlife management publications and conferences have openly and often discussed ways of persuading the public to share nativist antipathy toward non-native species. Dire warnings that popular non-native species might displace seldom-seen native animals and plants have had little or no effect.

Eventually efforts were made to introduce the use of the term "alien species" in place of "exotic species." This was slow to catch on, and for the first decade or more that "alien species" appeared in print, it was associated mainly with science fiction and teenage behavior, rather than ecology and biology.

Ecological nativists eventually began trying to introduce the term "alien species" in place of "exotic species." This also failed to kindle. For the first decade or more that "alien species" appeared in print, it was associated mainly with science fiction and teenage behavior, rather than ecology and biology.

Only in 1993 did "alien species" gain even marginal visibility, and the term has never been used by U.S. newspapers at more than about a third of the frequency of "exotic species." 1993 also brought an almost fourfold increase in coverage of "illegal aliens," and an almost fivefold rise in coverage of "illegal immigrants."

Indicative of which non-natives were of most public concern, "illegal aliens" were mentioned seven times more often in 1993 than "exotic species" and "alien species" combined. "Illegal immigrants" were mentioned three and a half times more often.

The impact of 9/11

Discussion of "invasive species," not even mentioned in print before 1988, likewise rose in 1993, reached statistically significant visibility in 1995, and achieved a virtual dead heat with "exotic species" by 2001, coincidental with the first external attack on Americans on American soil since Pearl Harbor, 60 years before.

Attention to "invasive species" then nearly doubled in one year, tripled in two years, and by 2006 occurred at four times the frequency of "exotic species."

How that happened appears to have little to do with increasing recognition of an actual problem, as "exotic species" and "alien species" were discussed no more often than before. Yet mentions of "illegal aliens" and "illegal immigrants" surged to five-year highs in 2001, and rose after 2002. Discussion of "illegal aliens" in 2006 soared to the highest point in a decade, while discussion of "illegal immigrants" nearly doubled, far surpassing the 1994 previous peak.

What this means to animals and public policy appears in the funding allocated by Congress to support the official U.S. government extermination agency, USDA Wildlife Services--which originally focused entirely on killing native predators of introduced livestock. Ancestrally part of the U.S. Geological Survey, funded to extirpate wolves from the continental U.S. in the early 20th century, this agency was moved to the U.S. Fish & Wildlife Service, retitled Animal Damage Control, and assigned to exterminate coyotes in 1930. Under the Fish & Wildlife Service, coyotes were massacred in record numbers year after year, yet spread from the southeastern quadrant of the U.S. to all 48 states plus Alaska. Amid indications that the Fish & Wildlife Service had become uncomfortable with the predator control mission, and under pressure from western ranchers to kill even more coyotes, former U.S.

President Ronald Reagan moved Animal Damage Control to the USDA in 1986. The USDA renamed the agency Wildlife Services to try to shake the murderous reputation established by Animal Damage Control, but without success.

Wildlife Services, with a 1998 budget of $28.7 million, was nearly abolished in June 1998 by the House of Representatives. A motion by Peter DeFazio (D-Oregon) that would have in effect disbanded Wildlife Services actually cleared the House on first reading, strongly supported by pro-animal organizations and some environmental groups, who recognized the mandate of exterminating predators as inherently anti-ecological, and especially mistrusted the use of chemical sprays and poisons. The DeFazio motion, unfortunately, was defeated on a second vote after frantic rancher lobbying.

Ecological nativists then joined with ranchers in racheting up alarm about "invasive species," managing to nearly triple coverage during the next year.

At instigation of then-U.S. Vice President Albert Gore, then-U.S. President Bill Clinton in February 1999 reinforced and enormously expanded the role of Wildlife Services by creating the Invasive Species Council, whose continuing existence is reauthorized by the so-called REPAIR Act passed by the House of Representatives on October 23, 2007. The main stated goal of the Invasive Species Council is to eradicate such non-native "nuisance species" as kudzu weed, gypsy moths, zebra mussels, and fire ants-by hiring Wildlife Services.

In the fine print, however, the anti-"invasive species" mandate extends to practically any species hated by anyone influential.

The strategy of preserving Wildlife Services by aligning it with the nativist philosophies of many major environmental groups succeeded bigtime. Under current U.S. President George W. Bush, the USDA Wildlife Services budget has expanded to $78 million in fiscal 2007, nearly three times the 1998 budget. Since the Bush administration in 2004 pushed through Congress an amendment to the 1918 Migratory Bird Treaty Act that stripped more than 100 bird species of protection, Wildlife Services can kill animals with less restraint than at any time since the 1973 passage of the Endangered Species Act.

Bio-xenophobia

And there is no longer much opposition to the killing from most of the environmental community. Many of the biggest environmental organizations are now preoccupied with human immigration issues, ranging from the effects of increased human population to the question of how fencing the U.S. border with Mexico may affect jaguars and pronghorn. The Gray Ranch, a Nature Conservancy property in southern New Mexico, includes routes often used by illegal immigrants. The Sierra Club has been deeply and bitterly split by debate over member resolutions, so far not approved, opposing immigration.

Ecological issues associated with human immigration are real and must be addressed, not least because they are probably only beginning. The most recent projections of the effects of global warming suggest that huge movements of humanity are inevitable, as result of droughts, floods, fires, rising seas, and possible famines. The human movements will be only one symptom of environmental changes that are already starkly evident in the receding snowcaps on most high mountain ranges, worldwide. Species evolve in response to habitat, not points identified by a Global Positioning System, and the habitat that many North American species prefer is already several hundred miles north of where it was just a few decades ago.

Climate change and ecological transformation are inevitable, even if the global warming trend is reversed well short of the worst-case scenarios. In view of that circumstance, rigidly defining "native" v.s. "non-native" species is an exercise in futility, no matter what names are used for them. Nature, not human intervention, will decide where animals and plants "belong" and thrive.

Bio-xenophobia looks more and more like just another symptom of plain old-fashioned xenophobia: the fear of anything exotic or alien, invasive or not.