An August Nature Ramble in the Blue Ridge

August 21, 2017

Nature Notes by Bill Dunson

 

 

After Margaret and I sold our 107 acre wildlife farm near Galax, VA, last November, we have been “homeless” during the summer escape from Florida heat. We are slated to close soon on a home with two acres near Boone. NC, as a replacement that will better suit our aging bodies. In the meantime we have enjoyed exploring the mountains around Boone for its considerable natural wonders. In August the birds have mostly finished breeding and reduced their vocalizations, so we enjoy watching insects and anything else in the natural world that draws our attention.

I was surprised to find that in August the most common large butterfly near Boone is the pipevine swallowtail. This butterfly is toxic due to consumption of pipevines by the caterpillar. It advertises this fact by a distinctive blue color on the inside of the wings and a row of bright orange spots on the outside of the hindwing. A group of butterflies including the closely related female black tiger swallowtail, and the unrelated red-spotted purple (an admiral in the brushfoot family) mimic the pipevine swallowtail and thus obtain some protection from predators. Strangely enough only some female tiger swallowtails are black mimics; other females are yellow as are all males. This not only confuses predators, it makes it difficult for humans to identify the “black and blue” butterfly mimics.

Milkweeds are growing in many places and not only attract monarchs but a number of other insects that specialize on these toxic plants. The caterpillars of the milkweed tussock moth are often found eating milkweeds in late summer when the leaves are tougher; their bright colors and bristles must serve to warn predators that they are toxic. The bright red milkweed beetle similarly has warning colors; it is often called the four-eyed beetle since each eye is divided by the base of the antenna.

Another insect that humans and predators have learned to avoid is the yellow jacket wasp. I literally ran into a nest in the woods hanging from a branch while looking at the ground and got stung on my lip; I was surprised that this marvelous hanging paper nest was not inhabited by hornets, but by aerial yellow jackets; a more common yellow jacket species nests in the ground. These intricate nests are abandoned during winter when all of the wasps except the queen die.

I have not seen many reptiles in the cooler high elevations but did find this “snake in the grass,” a garter snake basking in the sun on a cool morning. It was well camouflaged except for the bright red tongue.

There is often debate/controversy about the value of exotic shrubs for native birds and this photo of a young mockingbird feeding on the fruits of an exotic Mariesii viburnum is interesting. Many birds eat fruits from such exotic plants (privet is widely utilized especially by thrushes during winter). A study in PA showed that areas containing exotic plants with fruits attracted many birds. One question that remains is whether this benefit is offset by problems with the supply of insects needed by birds to feed their young. In any case the rigid dogma that exotic plants are all bad is unsupported by the facts. Instead a careful evaluation of the specific value for wildlife of each plant is needed, whether native or exotic.

So continue to enjoy the wonders of the natural world as they change during the seasons. I especially urge birders not to stop going on field trips in summer just because the exciting times of migration and breeding are at a low ebb. Not only are birds ecologically connected to the rest of their natural communities, but the insects, amphibians, reptiles and plants are really quite interesting and beautiful.

Bill Dunson

About Bill Dunson

Bill Dunson, born in rural Georgia, skipped 12th grade and went directly to Yale. Bill subsequent-ly received a PhD in Zoology from the University of Michigan, studying softshell turtles. Bill is Professor Emeritus of Pennsylvania State University thanks to a career spent entirely at that institution, teaching and doing research on the physio-logical ecology and ecotoxiciology of reptiles, amphibians and fish. Always curious about nature, Bill has dedicated his life to learning and sharing his knowledge with others. He has served on many advisory boards here in Southwest Florida to preserve the water that gives life to our region.

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