Steven Nett, SONOMA COUNTY REGIONAL PARKS BLOG
No, it’s not the zombie apocalypse. This threat is from invasive plant and animal species that have wormed their way into Sonoma County despite best efforts to stop them. Some are just as scary, gruesome and strange as fantasy creatures. But unlike the fictional walking dead, these invaders can do actual harm.
Take the brown-headed cowbird (Molothrus ater.) Cowbirds originally lived on the Great Plains, following bison that scared up a rich diet of insects. Because their food source was mobile, cowbirds, didn’t have the luxury of sitting on nests to raise their young. Instead, they developed the strategy of laying eggs in the nests of other birds, who then unwittingly feed and raise them. To ensure they do, cowbirds often remove the host bird’s own eggs.
When humans brought cattle to Sonoma County, the cowbirds followed. Today, two of California’s native birds, the least Bell’s vireo (Vireo bellii pusillus) and willow flycatcher (Empidonax traillii), are listed as endangered because of brown-headed cowbirds.
This is just one case of the silent ongoing battles between natives and invasive species in Sonoma County.
Then there’s medusahead (Taeniatherum caput-medusae.) Medusahead is a fast-spreading grass with a nasty survival skill: The plant incorporates exceptionally large amounts of fine silica (the raw material used to make glass) into its leaves, stems and spiky awns, the needle-like crowns (pictured below) that give medusahead its fearsome name.