Some bird seed may pose threat to native plants
As we are once again greeted with the white stuff and temperatures continue to drop, many people (myself included) are filling bird feeders to provide a helping hand to our feathered friends.
At this time of year, many bird species gather into large flocks, roving widely in search of food. Most of these will congregate readily around bird feeding stations. What does this have to do with invasive species? Well, as it turns out, some of the mixed bird seed packages may be harbouring seeds of invasive plants.
Mixed seed is commonly marketed as “wild bird seed”, “wild bird mix”, “finch mix,” and so on. There are no regulations about any of these mixes. Seed houses and retailers mix their own and they may not declare the contents on the package.
Throughout the year, I visit many private properties and help to identify invasive plants and provide management advice. While I cannot always be certain of the original source of invasive plants, some of the more unusual species are commonly discovered either under a bird feeder or in the vicinity of garden plants commonly used by seed feeding birds.
This has led me to believe that the source of some invasive plants is indeed bird seed, and the birds then become vectors and assist the spread of these invasive plants. This conclusion is supported by two studies from the U.S.
An Oregon study identified seeds of more than 50 invasive plant species in 10 wild bird feed brands purchased in that state. All of the brands were found to contain invasive plants, with 10 of the plant species on the state's noxious weed list.
These included: buffalobur, bull thistle, Canada thistle, common ragweed, cuscuta species, field bindweed, jointed goatgrass, kochia, puncturevine and velvetleaf. No doubt many of these species sound familiar, as the majority of these invaders are problematic in our region and some were mentioned in previous articles.
When the Oregon researchers tested whether the invasive plant seeds would grow once they fell from a feeder, they found that about 30 plant species beyond the intended ingredients grew within 28 days. Four of those were state noxious weeds.
In Idaho, the Department of Agriculture conducted a study that found 54 of 92 animal feed samples contained viable noxious seeds.
Considering the results of these studies, it is not surprising that “strange plants” are appearing in gardens and other places. So if you do chose to feed the birds during the cooler months, please follow precautions.
Carefully select the seed mix, or better yet, create the mix yourself. Consider putting the seed mix on cookie sheets and baking in the oven on the top shelf at 325 F for about 15 minutes. The seed still tastes good to the birds, but the heat prevents germination.
In the spring, remove any unusual plants growing under or near your bird feeder, before the plant goes to seed.
And remember to use squirrel-proof bird feeders to avoid supplementing the diet of invasive squirrels.
As a side note, since writing last month’s article on invasive squirrels, I’ve now had reports of Eastern Fox Squirrels in Penticton and Eastern Grey Squirrels in Kaleden. Not good.
For information on invasive species go to our website: www.oasiss.ca or contact the Program Coordinator for the Okanagan-Similkameen, Lisa Scott, at 250-404-0115.