Everybody's thinking green these days. Among other things, that means that people are re-assessing some of the hidden costs of our world's interconnectedness: fossils fuels burned for travel; the complexities of job outsourcing, trade imbalances, and linked economies; and the flattening of cultural distinctiveness. We can add to this list the continual threat of invasive species. On the news this week, we can see that the swine flu virus has spread from New Zealand to Canada, from Mexico to Scotland. The global economy, which has no doubt brought us many good things, has also helped bring pythons to the Everglades (see Nicole's post from last week) and Phytophthora ramorum to California, Oregon, and Europe.
I came upon a review of what looks to me like a very interesting book (maybe I'll read it soon) about one of the ultimate invasions prompted by world exploration and commerce. Charles C. Mann's book 1491: New Revelations of the Americas before Columbus maintains that the common picture of pre-European-settlement America--as a mostly empty wilderness filled with small numbers of natives who lived "in tune" with their environment in a low-impact way--is incorrect. He gathers together recent scholarship that is building an understanding of these native societies as populous, technologically advanced, and sophisticated at manipulating the natural environment to provide food and material goods. According to this understanding, diseases brought by the first European settlers quickly decimated these societies, giving "wilderness" plenty of time to re-occupy North and South American landscapes before the Europeans arrived en masse to view what looked like an idyllic garden of Eden. This view is, of course, highly controversial, with anthropologists, archaeologists, sociologists, and historians slugging away on both sides.
The smallpox virus. Photo courtesy of CDC/Dr. Fred Murphy and Sylvia Whitfield.
There is no dispute, though, about the devastating nature of the diseases that settlers brought with them, whether they wiped out a quarter of the native population or ninety percent. No matter how different any given invasive species are from each other, their epidemiology can be quite similar when they are introduced into non-resistant host pools. In this respect, our coast live oak and tanoak populations are much like these native people exposed to foreign diseases.
Janice's post on Wednesday spotlighted some effective ways in which local education and citizen science can be leveraged for efforts against individual invasives. That post, along with some of Nicole's recent posts, inspires me to revisit some questions I raised a couple of weeks ago about invasive species. Are case-by-case reactions to these invasions the best way to deal with them, or do we need to develop a globally coordinated approach? Among the many environmental problems that beset us, should we place the threat of invasive species, and their potential to change our landscapes, high on the list? (To its credit, the USDA Forest Service did this in 2004, but now its list of emphasis areas has changed.) Is this threat a high enough priority to receive the same kinds of national coordination and policy-making that clean air and water, endangered species, climate change, and other major environmental problems receive?
In hot weather people tend to seek shade and restful activities during the day, waiting for the cooler nights to increase their movement; so too for snakes, at least that is my conclusion after multiple snake sightings last night.
As we made our way on Coastal Fire Road to Pantoll Station in Mt. Tamalpais Park, sitting squarely in the center of the road was a juvenile coastal rattlesnake. It seemed stunned, rather than energized, not even giving a small warning as I nearly stepped on the seemingly inert brown clump. As the clump transformed before my eyes into a beautiful snake, I made a mental note to watch the trail(side) more closely.
Coastal Rattlesnake (courtesy of http://www.californiaherps.com)
The extra attention paid-off as we were treated to two more snake sightings that night: a rubber boa and a ring necked snake. Afterward we reveled in our good fortune, as these natives are not commonly seen.
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Rubber Boa (courtesy of http://www.californiaherps.com)
Ring-necked snake (http://www.californiaherps.com)
The recent sightings of Burmese pythons in the Everglades National Park have not been as celebrated. In the latest issue of the New Yorker Burkhard Bilger spends time with wildlife biologist Skip Snow, the python hunter, discussing how Everglades National Park came to have an unwanted, breeding population of pythons. As Burkhard explains in Swamp Things:Florida's uninvited predators , Snow has been trying, for years, to get officials to notice these pet shop escapees (likely dumped by owners), but there weren't enough sightings to generate any real interest. The general consensus was that spottings were isolated inoculations and the snakes would not become established. In 2003 when some unsuspecting tourists came across an adult alligator battling a full grown python and drew the world's attention to the snakes, Snow was called in to investigate. He discovered an established breeding population- more than 900 snakes have been found to date.
When one reads a story like the above, it may seem obvious what should have been done, but in reality dealing with introductions is rarely clear-cut. Knowing how, if and when to deal with an invasive species has challenged biologists, natural resource managers, and regulators for decades. Even when immediate responses are mounted, management can be difficult.
Take Phytophthora ramorum for example. By the time Sudden Oak Death was noticed in Marin P.ramorum, was already well-established. Due to its microscopic nature it had avoided detection and because it was a new pathogen, it was initially difficult to identify. Despite the uncertainty (the exact cause was unknown when efforts began) Marin County mounted an immediate response, working to localize and minimize the impacts. California moved quickly to create a task force to ensure a collaborated effort -working with other states and countries to minimize spread. Management strategies vary with levels of infection - small pockets call for eradication, where it is not yet detected prevention - and these differing management efforts must all be made in parallel with an increasing and changing understanding of the pathogen; not very clear-cut.
So what do introductions, be it pythons or P.ramorum, have in common? There is one commonality worth noting: the human role. Intentionally or unintentionally, we humans move species from their native habitats to new geographic locations where they can quickly become uninvited guests, overstaying their welcome, almost impossible to send home. Given the challenges we face in addressing invasive species once they are established, it seems a reasonable first step would be ensuring we, as individuals, minimize our role in introductions. A thought worth considering on Earth Day?
