|roadside Canada thistle|
Photo by J. Harrington
So, here it would seem we have a conundrum in invasive species management. Canada thistle is a prohibited noxious weed in Minnesota. The mechanical control method listed is "Repeated pulling and mowing will weaken roots, mowing when flower buds are just to open." Successful control of Canada thistle would probably affect goldfinches to some degree, since they are known to use the fluff for nesting. I don't find a record of goldfinch dependence on Canada thistle, but mowing when flower buds are just to open involves mowing at a time when roadside wildlife such as pheasants and waterfowl may have young in the nest, although June / July mowing of the first eight feet of roadside is allowed. Minnesota's Department of Natural Resources recommends "spot mowing" to protect wildlife and song birds. Perhaps I'm just too cynical, but I don't see much likelihood of that happening very often in very many places. Perhaps it would be best if people joined goldfinch and found productive uses for Canada thistle. Then folks could earn money harvesting it and bring about control that way.
|goldfinches, cardinal, junco and ???|
Photo by J. Harrington
If we're serious about invasive species control, we need to give more thought to whether we're trying to support biodiversity, in which case some invasive species may contribute to local biodiversity, trying to control and eradicate truly noxious weeds, or just engaged in feel good operations while we let major players in a global economy evade their responsibilities for minimizing invasions and contributing to control of existing noxious species. Each time I look at governmental guidance on this subject, I encounter distressingly mixed messages.
By John Poch
God knows the law of life is death,and you can feel it in your warbler neck,your river-quick high stick wristat the end of day. But the trophies:a goldfinch tearing up a pink thistle,a magpie dipping her wing tipsin a white cloud, an ouzel barrelinghip-high upstream with a warning.You wish you had a river. To makea river, it takes some mountains.Some rain to watershed. You wishyou had a steady meadow and pink thistlesbobbing at the border for your horizons,pale robins bouncing their good posturesin the spruce shadows. Instead, the lawof life comes for you like three menand a car. In your dreams, you win them overwith your dreams: a goldfinch tearing upa pink thistle. A magpie so slowshe knows how to keep death at bay,she takes her time with argumentand hides her royal blue in black.Shy as a blue grouse, nevertheless Goddoesn’t forget his green mountains.You wish you had a river.
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