Spring Happenings

April 10, 2015.  I’m in the swamp early this morning, an hour before daybreak. At 6:30 AM the “dawn chorus” starts, led off by cardinals, Carolina wrens, and tufted titmice, joined in by two recent arrivals from more southerly climes, the northern parula and yellow-throated warbler. To add to this cosmopolitan mix is a common winter visitor from the north, the white-throated sparrow, with its plaintive “old Sam Peabody-Peabody…..” or “oh sweet Canada-Canada.….” call, depending on your perspective. Something else out this morning is the first mosquito hatch of the spring. They are not that bothersome but get my attention, especially when I sit still for a while.

I’m hoping to hear the gobbler that was calling late in the evening two days ago, but so far hear nothing. I visit my old bird research plot and shortly pick up faint whiffs of odor in the air. The odor becomes more noticeable the closer I get to the plot. Soon I disturb a flock of a dozen or so turkey vultures perched high in the trees and at the same time realize the odor is the decay of flesh. It takes me a while to find it, a well-ripened carcass of a young pig. By the looks of the disturbed ground and leaves and a spot of carcass residue, something has recently dragged the pig remains for about thirty feet.

Black vultures roosting in cypress.

This incident is revealing of how vultures locate their food, a hotly-debated nineteenth-century natural history topic. In the 1820s, John James Audubon conducted one of the first experiments in America to determine how vultures locate their food. Conventional wisdom then, as now, was that they used their sense of smell, but Audubon thought it was done primarily through sight. His research proved the latter, and it was backed up later in the 1830s from tests done in Charleston by the Reverend John Bachman, a friend and collaborator of Audubon. However, there was a problem with their research in that apparently most of the vultures that responded to their experiments were black vultures, which have since been determined to indeed use sight to locate food. The turkey vulture, on the other hand, has been found to have a strong olfactory sense to locate its carrion food. This fact is clearly evident to me this morning as I stand by a smelly pig carcass under a dense, tall tree canopy, a carcass that could only be located by vultures with a sense of smell.

At 8:20 I hear my gobbler calling close and take cover at the base of a large sweetgum, hoping I might get a peek at him. Soon I’m rewarded with the image of a sky-blue dome, the top of his regal head, moving slightly away from me just above the switch cane. I get a full view briefly, about fifty feet away, before he disappears behind some large sweetgums. A few minutes later I hear him gobbling several hundred feet away. I trust he hooks up with some lady friends this morning.

Crayfish are the main link in the Congaree food chain. Photo by John Grego.

I get back on the base leg of the Weston Lake Loop trail and spot a barred owl perched low in a small holly tree on the edge of a slough between the trail and Cedar Creek. Cedar Creek has risen recently to nearly six feet, and the sloughs and backwaters are full of water. The owl looks my way and allows close approach to within fifty feet but then turns back, staring intently down at the edge of the slough. It soon swoops down and grabs a crayfish at water’s edge, then flies up to another low perch where it proceeds to swallow the mudbug in two or three gulps. Its second effort is also successful, but this time the owl remains at the water’s edge while consuming its victim. I watch for a total of thirty minutes, from 9:45 to 10:15, before the owl flies across to the other side of the slough. During this time it made five swoops, was successful three times, and came up empty twice.

I cross the Cedar Creek bridge and turn south onto the Oak Ridge trail, then walk southeast to a large, flat ridge west of Persimmon Pond. This ridge is dominated by even-aged sweetgum with a scattering of large pines, medium-sized cherrybark oak, and a few beech. It was probably cleared or partially cleared in antebellum times, perhaps for pasturage or a cowpen. It is bordered on the southern end by a long, narrow tupelo pond that I call Skinny Pond. As I walk along the east side of the beautiful blackwater pond I find on the edge an otter “latrine,” basically a community or family pooping ground used by several otters over a period of time. The otter poop ranges from very fresh to old and has a reddish color. Based upon my examination, the otters are eating nothing but crayfish as I find not a single fish scale in the remains. And the crayfish would explain the red color.

 

Switch cane in seed – a rare sight at Congaree.

Near the intersection of Oak Ridge and Kingsnake Trail I make an exciting find when I spot a small clump of switch cane with seed heads, something I’ve only seen once before in the Congaree. Switch cane, like most members of the bamboo family, only rarely produces seeds. The dense cane patches found in the Congaree are mostly clonal in nature, created asexually through spreading, underground rhizomes. The widespread abundance of switch cane in the Congaree indicates this is a successful method to colonize new ground.

On my way back, as I approach the bridge over Dry Branch, I finally record my first prothonotary warbler of the year, a male singing away at 2:00 in the afternoon between Dry Branch and Weston Lake. I spend a few minutes in vain looking for the songster, who is perched in the shadows about twenty feet up in some saplings. The next day I do see two males sparring with one another over territory in the muck swamp.