A Northern Cardinal eating red honeysuckle berries in the snow...sustenance or an "ecological trap?"

A couple weeks ago, while the snow was still fresh, Rick and I headed over to the Little Miami River to walk in the fluffy whiteness and look for birds. We saw White-breasted Nuthatches, Carolina Chickadees, Downy, Pileated, and Red-bellied Woodpeckers, Golden-crowned Kinglets, White-crowned and White-throated sparrows, Northern Cardinals, Blue Jays, Eastern Bluebirds, and a Red-shouldered hawk. We even saw a solitary Pied-billed Grebe swimming and diving in the river near the Lebanon cut-off bridge. It really was a winter wonderland, and we had the place to ourselves! All the birds were chatty (except the grebe), and they all were busy searching for food to help fuel them through the snowy day and upcoming night. At one point, we stopped and watched a male Northern Cardinal eating bright red berries from the frozen branches of an Asian Honeysuckle bush. If you look at the photo below, you can see berry pulp and skins still plastered to his bill. "At least these invasive bushes are good for something," I said to Rick...

A bright red Northern Cardinal was happy eating the bright red berries on an Asian Honeysuckle bush. 

When I got home, I googled, "Are Asian Honeysuckle berries good for cardinals?" I knew the berries had helped American Robins expand their range to the north, but I didn't know if the berries had helped Northern Cardinals. Along the Little Miami River, Northern Cardinals love the dense thickets that border the trail, and they claim the territory for their nesting sites in the spring, so they seemed to like the plant, but was the plant good for them? The first article to pop up in the search was written by John Carey on the National Wildlife website titled "Nonnative Plants: Ecological Traps; Offering alluring habitat for songbirds, exotic plants may actually decrease the animals' long-term survival fitness" (click here for the article). The article had a Northern Cardinal munching on bright red Asian Bush Honeysuckle berries, much like our little cardinal was doing. Uh...oh...

Asian Honeysuckle berries create an artificial indicator of health
Ecologist Amanda Rodewald of Ohio State University has been researching the affects of invasive honeysuckle on Northern Cardinals. Basically, the berries of Amur honeysuckle and other Asian invasive species might help cardinals get through the winters now, but 70 generations from now? Seems the berries artificially create bright red, healthy-looking males. Females usually chose the most colorful males as mates because bright red plumage indicates the birds have been eating berries packed with nutrients to make them strong and carotenoid pigments that make the feathers red. Asian honeysuckle berries contain plenty of pigments to color the feathers, but they lack the protein and fat the cardinals need to stay healthy and fit. So the bright "dye job" that results from a diet of Asian honeysuckle berries is misleading, and females may choose males that are not the healthiest. As a result, the couple will fledge fewer offspring, which over time could hurt the population.

Asian Honeysuckle bushes are an "ecological trap" for nesting cardinals
In another study, Rodewald uncovered an additional danger to Northern Cardinals. Asian honeysuckle bushes leaf out first among all forest plants. Northern Cardinals are early nesters, so the fittest males nest earlier than other birds by nabbing nests in the dense branches of the green and leafy honeysuckle bushes. Even though these sites appear to be the best, they aren't, and cardinals that nest in honeysuckle have a lower fledge rate than the less-fit cardinals who have to wait to chose "less desirable" sites in native trees and bushes. The earlier nesters fledge 20% fewer young, which means the healthiest birds are not reproducing at a normal rate. Why? Because cardinals nesting early in invasive honeysuckle are about the only birds nesting in the forest at that time, so they become marks for predators because they are easier to find. Rodewald concludes "breeding in honeysuckle seems to flip natural selection. It is a kind of ecological trap." (Check out the entire article for details on Rodewald's research and additional findings by other researchers.)

Eliminating non-native invasive plants from your yard...
I've been battling invasive honeysuckle from my yard for years. It's just about gone now, and I've replaced it with several varieties of native viburnum bushes, Staghorn Sumac, holly bushes, and others. The National Wildlife Federation (NWF) advises trying to eliminate the invasive shrub from your yard. Botanist Bruce Stein, National Wildlife's director of climate change adaptation writes, "While many nonnative plants are fairly benign, others can be ecologically destructive. We need to pick our battles wisely by figuring out which ones we can live with and which, if left unattended, will undermine our ecosystems.”

Click here for a pdf by The Ohio State University titled, "Controlling Non-native Invasive Plants in Ohio Forests: Bush Honeysuckle," for a description of Amur, Morrow, and Tartarian honeysuckle (Lonicera spp.) and recommendations on how to get rid of it.

Click here to learn more about invasive species and how NWF is working to stop their spread.