Winter keeps coming in fits and starts, and our migratory birds here in the Blue Ridge seem in no rush to keep moving south. Some of these lagging migrants have been taking advantage of a late-fruiting vine that’s festooning the crown of a small tree near my house.
A couple of cedar waxwings – one of my favorite songbirds because of their exquisite plumage – stopped to chow down on the fruit early in December. These birds appear in flocks in the spring and summer, descending on black cherry and other fruiting trees and picking them clean in minutes. Typically they’re gone to their winter quarters further south by this time of year. Other birds, including pileated woodpeckers, northern cardinals and several species of sparrows, have also been dining on the fruit.
So what fruit are they eating, exactly? The fact that the fruit is more than 25 feet up in the tree made identification difficult, but I could make out that it was small, clustered in bunches and hanging from a vine. Only a single, curled brown leaf remained on the vine. It looked like it belonged in the grape (Vitis) genus, but it was hard to be sure at that distance, and the leaf disappeared the next day.
If this was wild grape, which of the several species native to Virginia was it? It had to be one that ripened late in the season, since the other grapes nearby had ripened and been consumed by wildlife by the end of October.
One morning after a windy night, I had the good fortune of finding a cluster of the fruit on the driveway near the tree. Looked like grapes to me, but the fruit was so small and shriveled that it was hard to tell.
I called my friend, Robin Williams, who serves on the boards of my Master Naturalist chapter and the Virginia Native Plant Society, to see what she thought. I sent her photos of the fruit on the stem and one small seed I’d squeezed out of one of them.
After perusing the photos, Robin concurred that it probably was a grape, likely a frost grape (V. vulpina) but wasn’t’ sure. She suggested I contact Jake Hughes, lead biological science technician for Shenandoah National Park, to get his opinion. As Robin noted, Jake loves tackling plant identification and is good at it.
For years, Robin and other Old Rag Master Naturalists members had been helping Jake clear invasive exotic plants out of a Blue Ridge Montane Alluvial Forest, a scarce and vulnerable ecosystem in Buck Hollow, just inside the park’s boundary. I’ve joined them a few times, and we spent most of our time pulling out Japanese honeysuckle, oriental bittersweet and other exotic vines that had taken over – so Jake is intimately acquainted with these climbers.
I sent Jake the photos, and he concurred that it looked like a Vitis species, narrowing it down to probably summer grape (V. aestivalis) or frost grape (V. vulpina). As he explained, both of these have stems with “brown, shredding bark and small, blueberry-sized dark purple fruit and climb by extending tendrils.” While I couldn’t see the tendrils up that high, the rest certainly fit.
Jake added that there are several other native wild grape species around, such as the fox grape (V. labrusca), but “they are either much less common or have larger fruit.” He pointed me to a U.S. Department of Agriculture website for identifying plants (plants.usda.gov) so I could check out native grape species for myself. He also concurred that, without the leaves, it would be hard to clinch the ID.
Since, as its name implied, frost grape ripens later than summer grape, my guess is that the grape in question is V. vulpina. Whatever the species, wild grapes are an important component to our native ecosystems. As Jake put it, “The grapes are native species with tremendous wildlife value. The fruit are consumed . . . by numerous birds. They’re also an important food source for many mammals – black bear, raccoon and probably many others. And I’m sure there are insects and other invertebrates that depend on grapes.”
In consulting “American Wildlife & Plants: A Guide to Wildlife Food Habits,” by Alexander C. Martin, Herbert S. Zim, and Arnold L. Nelson, I found more than 50 native Virginia bird and mammal species alone that feed on wild grapes. Next I checked Doug Tallamy’s book “Bringing Nature Home,” which lists the host plants of native moths and butterflies. In it I found that several species of sphinx moth (also known as hawk moth) depend on wild grapes as hosts for their larva.
Wild grapes are fast, aggressive climbers and can spread easily, so some management may be required to keep them from overtaking areas of edge or forest. If you’re lucky to have wild grapes nearby, however, you can enjoy seeing many native wildlife species taking advantage of the food and shelter they provide. We humans also like to consume wild grapes – right off the vine, or in jams or wine made from them.