Monday, August 1, 2011

GREAT EXPECTATIONS: August in the Piedmont

Birds.− In August, migrants such as chestnut-sided warblers, magnolia warblers and blackburnian warblers begin to pass through North Carolina as they head towards the neotropics for the winter. These warblers will be duller colored than they were in the spring, having lost their vibrant breeding plumage and molted into drabber winter attire.

Vermivoric warblers (i.e., those that eat worms), which stop in the Piedmont for a quick meal before heading further south, can often be found with “friends”. This time of year, experienced birders will often search for American redstarts and black-and-white warblers by first finding a group of more easily located Carolina chickadees and tufted titmice.

Did you know that warblers were the subject of classic ecological study by Robert MacArthur (1930-1972)? Before MacArthur’s study, people thought that five species of warblers -- Cape May, yellow-rumped, black-throated green, Blackburnian and bay-breasted – actually occupied the same “niche” since they all used the same breeding grounds. By watching foraging warblers and dividing individual trees into vertical and horizontal observational zones, MacArthur found that each warbler species actually used a different part of the tree. For example, the bay-breasted warbler fed around the middle-interior of the trees, while the Cape May warbler stayed toward the top-outside of trees. MacArthur showed that the warblers were dividing up a limited resource, a phenomenon now known as “niche partitioning.”

Butterflies.− Expect a pulse in the migrant cloudless sulphurs and little yellows and lookout for the 2nd and 3rd broods of the tawny and hackberry emperors, respectively.

Also, expect to see a continued rise in swallowtail sightings, this month, after the mid-summer lull. In fact, very lucky lepidopterists (i.e., butterfly observers) might even come across a bilateral gynandromorph tiger swallowtail, like the one that was seen last year in Hillsborough. A gynandromorph is an organism that has both male and female characteristics; bilateral gynandromorphs are half male and half female and mosaic gynandromorphs are a mix of each. Gynandromorphs are the product of sex chromosomes that do not split apart in the typical way during the first division of the zygote (i.e., the fertilized egg).

Reptiles & Amphibians.− Keep an eye out for snakes and turtles, especially baby box turtles, which begin to hatch this month. Fence lizards and skinks are also out in abundance. Green anoles can also be sighted. Listen for large choruses of green tree frogs and bullfrogs, as well as occasional calls from eastern narrow-mouthed toads and eastern spadefoots.

Other Insects.− Expect a pulse in grasshopper and cicadas activity this month. You might also find dead or dying luna moths this time of year. August marks the time of their third and final brood of the summer.

Did you know?

· The luna moth is one of the largest moths in the United States, with lime-green wings expanding to nearly four and a half inches.

· Luna moths only live for 1 week!

You may also see green lacewings flying around in the evenings. Lacewings are fascinating insects that are important predators in many agricultural systems. They consume aphids and other soft-bodied insects. Predators of lacewings include bats and spiders. Interestingly, lacewings are sensitive to the frequencies emitted by bats when hunting and will try to evade them. Lacewings also will not struggle in a spider web, but attempt to free themselves by chewing the strands of the web.

In Bloom this Month.− Be on the lookout for some striking August flowers:

In Bloom:

SMALL-FRUIT AGRIMONY – Agrimonia microcarpa

AMERICAN BEAUTY-BERRY -Callicarpa americana

TRUMPET-CREEPER – Campsis radicans

TICK-TREFOIL – Desmodium nudiflorum

DEVIL'S-GRANDMOTHER - Elephantopus tomentosus

JOE-PYE-WEED – Eutrochium (syn.Eupatorium) dubium

SNEEZEWEED – Helenium autumnale

SCARLET ROSE-MALLOW – Hibiscus coccineus

ST. ANDREW’S CROSS - Hypericum hypericoides

CARDINAL-FLOWER – Lobelia cardinalis

GREAT BLUE LOBELIA – Lobelia siphilitica

CORAL HONEYSUCKLE(S) - Lonicera sempervirens

BLACK-EYED-SUSAN - Rudbeckia fulgida

GREEN-HEAD CONEFLOWER – Rudbeckia laciniata

ROSINWEED – Silphium sp.

AXILLARY GOLDENROD - Solidago caesia


IRONWEED – Vernonia sp.

Piedmont Habitats.− Did you know that oak savanna once stretched across North Carolina’s Piedmont?

The savanna community consisted of grasses and forbs under a thin canopy of oaks and sometimes graded into true prairie. This system was documented by a number of North Carolina’s early explorers and settlers, including John Lawson and Bishop August Gottlieb Spangenberg. While traveling around the Yadkin River in the mid 1700s, Lawson noted that he had “travell'd, this day, about 25 Miles, over pleasant Savanna Ground, high, and dry, having very few trees upon it, and those standing at a great distance. The Land was very good, and free from Grubs or Underwood.”

The Piedmont savanna was formed and maintained by a variety of factors, including climate, characteristic soil types (including saturated, basic or droughty soils), both natural and American Indian set fires, and perhaps grazing by now diminished herbivores, such as bison. Now nearly gone in North Carolina, Piedmont savannas were incredibly diverse, containing nearly 300 plant species. Johnny Randall, the assistant director for conservation and natural areas at the UNC Botanical Garden, is optimistic about restoration efforts for this community type. Local savanna restoration sites include Penny’s Bend Nature Preserve and parts of Mason Farm Biological Reserve.


Cook, D. 2001. The Piedmont Almanac. Raleigh, NC: Barefoot Press.

Daniels, J. C. 2003. Butterflies of the Carolinas. Cambridge, MN: Adventure Publications, Inc.

Ehrlich, P., D. Dobkin, and D. Wheye (1988). The Birder's Handbook. New York: Simon & Schuster.

Juras, P. 1997. The Presettlement Piedmont Savanna - a Model for Landscape Design and Management. University of Georgia Master’s Thesis.