Monday, February 1, 2010

Great Expectations: February in the Piedmont

Birds.− In the heart of winter in North Carolina, not many changes are happening in the bird world. By the end of the month, purple martins and tree swallows will begin to reappear. Barred owls start hooting their mating calls this month. Also, woodcocks begin their elaborate courtships in February. It is worth braving the cold this month to watch male woodcocks spiral skyward and fall rapidly back down to earth making a distinct “peenting” call in hopes of attracting a mate.

Ever wonder what birds eat this time of year? Our year round residents have a remarkably flexible diet that adapts to changing food supplies. For example, eastern bluebirds typically feed on insects and other invertebrates during the warmer months, but depend on small fruits and berries to satisfy their hunger in the winter months. Some birds, including crows, jays, nuthatches and titmice, will even feast on carrion if needed. Carolina chickadees are particularly flexible. During the summer, 80-90% of their diet is made up of small insects and spiders. In winter, approximately 50% of the Carolina chickadee’s diet is composed of seeds and fruits, including those of poison ivy, Virginia creeper, pines, and eastern redbuds, with the remainder being made up of their typical warm-weather cuisine.

Butterflies.− Butterfly enthusiasts can rejoice: many of our over-wintering species will re-emerge this month with the slightly warmer weather. Near forested habitats, one might expect to see question marks, eastern commas and mourning cloaks. In open habitats (e.g., fields and roadsides), expect to find American ladies, late sulphurs, orange sulphurs, clouded sulphurs and cabbage whites, a commonly seen species that was introduced from Europe.

Reptiles & Amphibians.− This month, expect to continue hearing southeastern chorus frogs and spring peepers. You might also catch the sharp, repetitive clinking of a northern cricket frog, the musical trill of an American toad, the low-pitched croak of the pickerel frog or the sheep-like bleat of the eastern spadefoot. Also, continue to look for breeding salamanders.

In Bloom this Month.− February is a great month to eradicate any non-native, invasive plant species growing on your property, many of which are easy to identify even in the middle of winter. In the southeastern United States, most invasive species arrived from Europe or southeast Asia (areas that share the deciduous forest biome). These species have arrived accidentally (e.g., Microstegium, an invasive grass, arrived as packing material), as well as intentionally (e.g., the princess tree was introduced by horticulturalists.) Once an invasive species gets a foot-hold, it can alter the vegetation structure of a community, change food resources for wildlife, and even affect ecosystem-level processes such as sedimentation, erosion, soil chemistry and fire regimes.

Important Terms:
Exotic species – a non-native plant that will grow, but not spread in a given ecosystem
Invasive species – a non-native species that will spread and cause harm in a given ecosystem
Native species – a species that historically occurred in a given ecosystem
Noxious weed – any plant whose presence is detrimental to crops or desirable plants, livestock, land, other property or is injurious to public health (note: can be native)

Notable invasive plant species in our area:
Chinese privet (Ligustrum sinense)
Chinese wisteria (Wisteria sinensis)
Common reed (Phragmites australis)
English ivy (Hedera helix)
Hydrilla (Hydrilla verticillata)
Japanese stilt grass (Microstegium vimineum)
Mimosa (Albizia julibrissin)
Multiflora rose (Rosa multiflora)
Oriental bittersweet (Celastrus orbiculatus)
Princesstree (Paulownia tomentosa)
Russian olive (Elaeagnus angustifolia)
Sericea lespedeza (Lespedeza cuneata)
Tree-of-heaven (Ailanthus altissima)

Wildlife Profile.− This month’s wildlife profile is the MOURNING CLOAK BUTTERFLY (Nymphalis antiopa). The mourning cloak is one of the first butterflies to re-emerge in North Carolina. This species is the longest lived in the United States, surviving up to 11 months. The adults are dormant in winter, and then re-emerge, wings imperfect and worn, during the first warm days of late winter and early spring. This time of year, males are quite bold, bravely chasing birds out of their 300 m2 territories. In early spring, males and females perform a beautiful mating dance, spiraling upward through the air. The females will then lay clusters of eggs on their favorite food plants, black willows, as well as other willow species, elms, birches and hackberries. Although the females die shortly thereafter, caterpillars will emerge from the eggs in April. After three weeks, this brood will have pupated and emerged as fresh, young mourning cloaks. The adult mourning cloaks are usually found in woodlands, where they feed on tree sap (especially oak sap), rotting fruit and occasionally nectar, building up stores for the winter.

Did you know?
• Mourning cloak butterflies spend the winter frozen in “cryo-preservation.”
• They can live up to 11 months in the wild.
• Their common name refers to their resemblance to the traditional cloak one would where while in mourning.
• Caterpillars live communally in a web and feed on young leaves.

Identification: The mourning cloak has brown wings with small blue spots bordering a yellow edge. It reaches 2 ¼ to 4 inches in length.

Cook, D. 2001. The Piedmont Almanac. Chapel Hill, NC: Mystic Crow Publishing.

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

LeGrand, H. E. Jr., and Howard, T. E. Jr. 2009. Notes on the Butterflies of North Carolina, 19th Approximation. Available at

Read, M. 2005. Secret lives of common birds: Enjoying bird behavior though the seasons. New York: Houghton Mifflin.

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