Well, that seems like an easy question, right? Yet when it comes to invasive plant spread, some people continue to be unaware of how invasive plants get around (the classic answer is: “It never spreads in my yard, I don’t think it’s invasive.”). I think a refresher on the birds and the bees seems to be in order.
|Callery pear fruit|
Invasive plants arrive here in different ways originally, but once they’re here they spread thanks to the 3 W’s: wind, water, and wildlife (not including those that spread by runners). Of course, some plants were specifically encouraged to support wildlife; the plants known as thorny and autumn olive (Elaeagnus sp.) are in that group. They’ve since become one of the top invasive plants in Georgia and the southeastern US, and they continue to be sold and planted today.
Fruit-bearing invasive plants are often spread by birds as they eat them, fly some distance away, and deposit the seeds of the fruit in new places. This behavior by birds leads some people to believe that there is a net positive impact on the ecosystem if birds are able to eat the fruits. What is not well understood is that these fruits are often not the food of choice for these birds but rather one of low nutrition or last resort. Poor nutrition can slow migration and make birds vulnerable to other risks. One particular non-native plant, Nandina domestica, actually has fruits that can be toxic to cedar waxwings because they can gorge on fruits.
|Cedar Waxwing eating Pyrus calleryana in winter. |
Photo from Pilot Online Original Source: Carol Annis
Once humans know better, we can help heal the habitats that our native birds share with us. Our landscapes were planted after native plants were removed from the site. It’s not just our yard, it’s a million yards, billions of acres that have been disrupted one acre at a time, but we can begin to stitch some back together and create new habitat. Plants which fed birds then – native plants – can be added back.
Fruit-bearing native plants produce fruit from spring to fall (starting with black cherry), but let’s focus on what migrating birds are eating in the fall and what winter residents are eating in the winter since we’re in the here and now.
Fruits for fall migrating birds include native viburnums, spicebush (Lindera benzoin), beautyberry (Callicarpa americana), shrub dogwoods (e.g., Cornus amomum), most hawthorns (Crataegus) as well as late blueberries (Vaccinium arboreum) and blackberries (Rubus).
In the winter in Georgia, native plants with late or persistent fruits include flowering dogwood (Cornus florida, or now known as Benthamidia florida ), green hawthorn (Crataegus viridis), native shrub and tree form hollies (Ilex), and eastern redcedar (Juniperus virginiana).
These native fruit-bearing plants benefit not just birds that eat fruits but also others. Native plants will also offer beneficial support to insectivores because butterflies and moths can use native plants for caterpillars. Native plants support birds in far more ways that fruit and that is their superpower advantage over non-native plants.