How non-native species are disrupting Sonoma County’s valuable ecosystem
To some, they’re a little like invaders from space in a science fiction movie: nearly invisible, hard to detect, and with a mission to destroy. Many are already among us. And thousands more are approaching. They are invasive plant and animal species, and stopping them is a full-time job, particularly in places with a lot of agriculture at stake, like Wine Country.
But trying to manage, or at least slow them down, is a challenge, because, according to state and local authorities, most of the invaders are getting a free ride in: from humans.
Take the imported red fire ant, Solenopsis invicta. As anyone who’s met one can testify, it’s a notoriously bad actor. They pack a burning, painful sting, react aggressively if their nest is disturbed, and have the nasty habit of stinging and biting repeatedly in swarms after climbing your legs. Originally native to South America, imported red fire ants are now well-established in large colonies across many places in the southern United States. But they still haven’t turned up in Sonoma County and Northern California.
How long that lasts is an open question.
Last summer agricultural biologist David Jagdeo was on duty in Petaluma inspecting shipments when he opened an unmarked package from Texas on its way to a local pet store. Inside, he found 10 vials holding live ants, one with eggs and adults of the red fire ant, invicta (ants are the diet of choice for some reptiles, including the horned lizard).
That import was seized. But Sonoma County is under constant siege from a dizzying array of invasive plants, animals, insects and microbes.
And the problems they cause can be huge. Invasive species disrupt habitats, crowd out and endanger native plants and animals, choke waterways and deplete water resources, spread disease, and even increase fire risk. Insect pests brought into California from other states or countries can have devastating effects on citrus groves, grapevines and other economically important agricultural crops.
According to the Center for Invasive Species Research at UC Riverside, invasive pests already cost California as much as $3 billion a year.
People have been importing nonnative plants and animals into Sonoma County since the Spanish arrived in the 1700s, and clearly, not all are considered invasive. Many are welcome. The honey bee, for example, was transplanted from Europe because relatively few of California’s 4,000 native wild bees make honey or can be conveniently managed in hives.
Unfortunately, according to the California Native Plant Society, roughly 450 plants that were originally imported to California as ornamentals have “jumped the fence,” and are now rooted and competing in native habitats.
Pet fish, turtles, snakes and cats, released by their owners or escaped, are also now part of the invasive species problem in many regions.
To biologists and government agencies, invasive species are nonnative, aggressive colonizers that are quick to spread and hard to eradicate, and can have a substantial negative impact on other species or entire habitats.
Officially, the California Department of Fish and Wildlife, which manages the State’s Invasive Species Program, considers a species invasive if it threatens the diversity or abundance of native species. Martha Volkoff, the department’s program manager, points out that many invasives, from ice plant to oat grass to Norway rats, are now so widespread, they’re here to stay. The state’s efforts are largely concentrated on reducing their impact and further spread, and especially, keeping new aliens out. But that’s an ongoing challenge.