January 10, 2015. The weather has warmed up slightly since the day before yesterday, but there is still a lot of ice in the swamp. This morning’s weather is clear and cool, the high at 10:00 being about 35º. I am walking down the Sims Trail, and soon notice a lot of bird activity coming from the edge of the trail. A hermit thrush flushes from the leaf-littered ground and perches on a small twig in the middle of the path, affording excellent views. There are several golden-crowned and ruby-crowned kinglets foraging on the branches and twigs of the bare hardwoods. One of the golden-crowns is a male, as determined by the orange crown-patch that almost glows. Most of the golden-crowns I see at Congaree are females, having yellow crowns. This suggests to me that a differential migration of the sexes may be taking place, a phenomenon well-known in the bird world. Differential migration means that in winter females and immatures migrate farther south than adult males, which stay closer to the summer breeding grounds. Since adult males compete with one another for the best breeding territories, the ones that move the shortest distance south in winter will be able to arrive sooner on the breeding grounds in spring migration and get a jump on the best territories. There is a trade-off here, however, and that is the males that don’t move far enough south may not survive a harsh winter and not be around to spread their genes later.
I notice movement coming from a hanging sweetgum limb twelve feet off the ground, sporting clumps of dead leaves. At first it looks like a kinglet except it is bigger and moves slower. It is an orange-crowned warbler. This drabbest of warblers (Roger Tory Peterson once stated that the best field mark for this dingy olive-green bird was the fact that it had none; the faint sliver of orange on the crown is obscure and rarely seen this time of year) is foraging through the clumps of dead and dried sweetgum leaves. It pulls out an unsuspecting insect or spider twice during the short time I watch before it flies off. Its first victim is too small to identify, but the second is large, appearing to be a spider, and the warbler has trouble subduing it before swallowing it down.
Other birds in this loose winter foraging flock include white-breasted nuthatches, tufted titmice, Carolina chickadees, Carolina wrens, goldfinches, a female black-and-white warbler, and another good find, a single pine siskin. I rarely see siskins anymore. They used to be quite common in winter at my bird feeders in town but started disappearing some twenty-five years ago. Siskins are an “irruptive” species, meaning their winter movements and food habits are tied in with their preferred seed diet from conifer cones, alder, birch, and other trees and shrubs (in the swamp they like sweetgum seeds); the seed crops themselves fluctuate in abundance. In years of poor seed production, siskins move farther south in winter to find other foods. But that still doesn’t explain why they nearly disappeared from my Columbia feeders. The only explanation I can come up with is the popularity of backyard bird feeding, which has “short-stopped” siskins farther north. This could also account for the disappearance of another winter finch formerly seen at my feeders, the purple finch.
A little farther down the trail several hermit thrush-sized birds flush from a debris pile left over from last February’s ice storm. I usually see a good number of white-throated sparrows in such spots, but these birds are too big and too beautiful to be white-throats; they are fox sparrows – large, robust finches with beautiful, rusty-red streaks on their flanks and bellies. This is another good find as they are not a common winter bird in the floodplain.
There are many young red maples growing on the edge of Sims Trail. Some sprouted up from canopy openings caused by Hurricane Hugo twenty-five years ago; others seeded in even earlier from cleared lanes on either side of the Sims Trail that were planted in winter rye by the Cedar Creek Hunt Club. One maple is now in full bloom despite the frigid temperatures of the past few days. What tough flowers they must be!
As I walk past Weston Lake and the big slough leading out of it, now full of water, an acquaintance wonders why there are not more ducks in the swamp. So far we have seen none this morning. It’s a good question. I do remember last year for the Christmas Bird Count we saw lots of wood ducks feeding on fallen laurel oak acorns in the water-filled sloughs and flats along the western boundary road. The swamp has not been flooded much this winter to bring in extra water for the ducks, and there are few laurel oak acorns this year. But still we wonder what the duck picture at Congaree was like a hundred years ago. I told my friend that probably one of the main reasons we don’t see many ducks here in winter is that within the past twenty-five years there have been hundreds, if not thousands, of acres of impoundments constructed and planted in corn and other duck foods on private lands on both sides of the Wateree and Congaree. A duck club adjoining the Congaree, for example, reported a staggering 15,000 wood ducks on one day last December.
I cross Cedar Creek at bridge “I” then turn south onto the Oak Ridge Trail. Soon I’m in the middle of a very large natural opening, caused by several fallen giants – loblolly pines, sweetgums, and cherrybark oaks, all within the past eighteen months. About the only trees left in this large opening are scattered American holly trees, a few of which produced berries this year; the robins have zeroed in on them, going after the red drupes with gusto.
A little farther down the trail I watch a bird foraging low in some hollies. At first I think it’s a kinglet, but something doesn’t look quite right, and with my binoculars, I identify another good find for the day, a white-eyed vireo. This species is an uncommon winter visitor in the swamp.
It’s now early afternoon and I take a lunch and hot-tea break. It’s a beautiful, crisp winter day, no warmer than 45º, with little wind and a magnificent blue sky overhead. I see a few turkey vultures and black vultures sailing over on flapless wings. This would be a great day to be on the river.