My recent post about tiger shrimp fit nicely into my current fascination with invasive species. My understanding of this particular shrimp is that it is definitely non-native, but more research is needed to find out what role it is playing in the ecosystem and whether or not it is invasive. That slight difference in wording depends on whether or not the new arrival crowds out a native species by competing for food or shelter.
Chinese Tallow, for instance, both displaces native vegetation and changes the chemical composition of the ground around it so that other species won’t grow there. It also uses vast amounts of water and can drain wetlands. Here on Dewees Island, we have been working hard to remove some plant invasives: our Chinese Tallow eradication program is restoring sunlight and water in the conservation wetlands in the middle of the island. We only garden with native plants, and any non-native species are confined to pots or containers.
Brown Widows are a non-native species that has worked its way up from more tropical locations by hitching a ride on kayaks, boats, or in cars. (I recently removed three egg sacs from the door of my car!) And fire ants are an invasive species here on the island as well.) One of the problems here is that the natural predators of these species have not been transported along with them.
Increased mobility of humans has changed whole ecosystems: In Guam, there were no snakes, so other animal populations didn’t learn or evolve to fear them. When brown tree snakes arrived in Guam 60 years ago as stowaways on either boats or planes, they began gobbling up birds. The bird population is significantly depleted on the island, and, with no birds to control the insect population, both small insects and the spiders that prey on them have exploded in numbers. You can listen to an interesting story on that here on NPR.
We are not the only victims of invasive species. Our native animals can become invasive in other areas. Some of our fairly innocuous animals have become serious nuisances in other places. The stingless comb jellyfish we pull up in a cast net at the crab dock are actually voracious predators, “capable of eating ten times its body weight per day, starving entire ecosystems by scarfing up everything at the bottom of the food chain.” New research shows how it manages to sneak up on its prey; this article from September’s Smithsonian magazine has all the details.
And perhaps we shouldn’t be surprised as a community that raccoons are a nuisance other places. 
Predators of raccoons here on Dewees include hawks, eagles, bobcats, foxes, owls, and alligators. And we have certainly found them to be a nuisance occasionally. But in other locations, they have wrought havoc on ancient temples and forests. Apparently, there was a Japanese TV show in the 70’s based on Sterling North’s book Rascal. At the end of the story, the family releases their now grown raccoon pet into a forest. Which might be fine in the US, where there are at least a few predators. This PBS nature show, Raccoon Nation, describes the problems the raccoons have created in Japan and Germany. (Forward to Chapter 6: Global Raccoons.) Thousands were released into forests, where they bred and multiplied.
Of all native animals in Japan, no single species has caused such atrocious damage. So we definitely need a strategy to tackle the issue now. Otherwise, it’s hopeless.
One thing you’ll notice in that video is that those raccoons bear little resemblance to ours– they are so fat they waddle like little bears. Ours have evolved with longer legs for reaching into fiddler crab holes and stretching over marsh grass and tidepools. Nonetheless, we appreciate all the apex predators who keep our raccoon population in check. Please comment in if you have seen a raccoon as prey for any of our local predators.
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Fascinating!! I need to go back and click on some of the links….bear-like raccoons? Now that is scary. Is Chinese tallow the same thing as Kudzu?
Judy,
I personally witnessed several raccoons who were victims of a predator between 2002 and 2010. A five hour event in 2009 by this predator reduced the population of raccoons on Dewees Island significantly. RIP, Cephas.
Chinese tallow is not the same as kudzu. Kudzu is a vine. See http://en.wikipedia.org/wiki/Kudzu
Chinese tallow is often called popcorn tree. See http://en.wikipedia.org/wiki/Chinese_tallow
Good post. I’m reading Jared Diamond’s “Collapse” right now and I was surprised to discover that invasive species have even been a primary factor in bringing down entire human societies. Yikes.
Cool article. It’s only a matter of time until the coyotes and armadillos show up. You all might be too remote for the armadillos out there. Our favorite invasive species is the Mediterranean Gecko. They are all over the place down town and in Mt. Pleasant.
I dont guess Cephas or our wheaten, Murphy, are “natural” predators, but we discovered the savage underbelly of our genial guy one cool fall weekend on Dewees when a lot of the spring coon teenagers had contracted distemper and were on the ground during the day. Murphy killed three coons in one weekend before we figured out what was going on and why and kept him on lead the rest of the vacation. ( after a trip across to be revaccinated for distemper and be on the safe side.). I think the Mosers have some coon-killing predators over at their house, too
I submit that a coonhound is a natural predator of raccoons and will track and tree despite any human command. Cephas was on a leash, as always, when he broke free to chase his prey in the conservation area off Old House Lane. That time I was lucky, no torn tendons as in two previous escapes which resulted in surgeries for a torn rotator cuff.
You are right, Dershie. Buttons, our 14 pound JRT mix, routinely decreases the population of coons and rats on Dewees. Most of the coons are bigger than she is.
Great article, Judy!