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Pigs and Foxes and Eagles, Oh My!

Via the Invasive Species Weblog (newly blogrolled), a story that’s all over Central Cost news – the Nature Conservancy and the National Park service have teamed up to eradicate feral pigs (Sus scrofa) from Santa Cruz Island. This is a local story, but it deals with a controversy that’s unfortunately relevant in just about every inhabited place on Earth – how to deal with invasive exotic species.

The essence of the problem is that non-native, rapidly multiplying feral pigs are consuming vast quantities of the limited resources on the small island, and thereby putting pressure on the 145 species of plants and animals that are endemic to the Channel Islands. They’ve also attracted golden eagles, which prey not only on the piglets, but also on the endangered Santa Cruz fox (Urocyon littoralis). The golden eagles seems to feel right at home, having taken over the habitat of bald eagles (which ate only fish, not foxes) that once inhabited the island, but disappeared in the 1960’s, possibly because of DDT dumping off of the California coast.

TNC and the NPS have instituted a program to reintroduce bald eagles to the island and relocate golden eagles back to the mainland, and have teamed up to hire a New Zealand group to eradicate the pigs. The latter move, as expected, really pissed off local animal rights groups:

“Native and non-native have no scientific validity,” [CHIAPA member Scarlet Newton] said. “Someone has to arbitrarily pick a date.” [Rob Puddicombe, the director of CHIAPA] said the notion of returning the island back to its native state is not feasible. He said that to determine which animals and plants are native, one could look at different time periods, including pre-white man, pre-cars or even pre-mammal, and get different results.

Newton said the Nature Conservancy’s plan is anything but restorative, and called the eradication of the island pigs a “massacre.”

Newton is mistaken in her claim about the definition of invasive species – an invasive species is introduced, intentionally or unintentionally, by humans, and is a threat to biodiversity in its new environment. Puddicombe makes the focuses on the part of the definition that deals with human influence and ignores the impact of invasives on biodiversity.

I have a tendency sometimes to get pedantic and offer a conclusion that I consider unquestionable, but I’d like to open this one up to discussion about intentional environmental manipulation. The environment is not and never has been in stasis, so simply removing a factor will rarely return an ecosystem to the state it was in prior to the introduction of that factor, and yet biodiversity is valuable not just from an ethical perspective, but also economically and scientifically. What basic philosophy ought to be behind decisions to intentionally alter an ecosystem?

My favorite question

By Hungry Hyaena (not verified) at March 20, 2005 - 4:35pm |

Thanks for pointing me in the direction of the Invasive Species Weblog. I'm sure to spend a lot of time there.

As far as your question is concerned, I'm torn and have been for several years. The threat posed by extic introductions is very real and the moves made to preserve ecological balance and current niche players are not justified only by a desire to maintain the status quo. Biodiversity is important for economic reasons, but also from a strictly human, aesthetic perspective; would you elect to wipe out the details of a landscape painting to leave only a green-brown smear? On the other hand, sometimes a crash in biodiversity is part of the deal. Given the infinite ways in which natural selection and evolution move, we have no way of knowing what will come from the accelerated rate of introduction, at least not in the same way we can predict where accelerated climate change takes us.

On a more immediate scale, the animal rights activists are fooling themselves if they believe they are curtailing animal suffering by stopping the hunting of feral pigs or deer. If left to their own devices, both the species they displace and, often, the pigs and deer themselves will face death by starvation or disease. Humans would be responsible for these deaths, too, no matter what the simple-minded arguments of animal rights activists may be.