Christmas Bird Count
December 14, 2014. This morning I’m participating in Congaree’s annual Christmas Bird Count (CBC) along with Steve McInnis and his wife Susan. The CBC is sponsored by the National Audubon Society and is one of the oldest, continuing field surveys of its kind in the world, dating back to 1900 when eminent ornithologist Frank M. Chapman first proposed counting birds rather than hunting them. As of 2014 there were more than two thousand counts conducted across the Americas, going as far south as Colombia and far north as Alaska. The Congaree CBC was started in 1993 by the late Robin Carter. John Grego now serves as the count compiler and coordinator. Despite its name, few counts are actually conducted on Christmas Day but over a three-week period from December 14th to January 5th.
The area of the count, consisting of a fifteen-mile diameter circle, is divided into sectors or routes with teams or individuals assigned to each sector. The idea is to simply identify as many species as possible and count their numbers (in many cases the numbers are only estimates). Our route this morning includes the Western Boundary Road all the way to the Congaree River and including part of the River Trail. This has been my usual route since first participating in the count more than twenty years ago. We start at 7:30 and finish up by mid-afternoon. Typical for this time of year, unless the weather is really cold, bird activity drops off noticeably after 10:30 or 11 and may stay that way until late afternoon.
We end up with a respectable total of 35 species, with the highlight of the day being a drove of 24 wild turkeys that crossed the road in front of us earlier in the morning. We also counted 16 red-headed woodpeckers, a far cry from last year’s 60 that Laura McCormick and I found on this same route (and as it turned out, in 2013 Congaree had the highest CBC count of red-headed woodpeckers east of the Mississippi River with 146 birds).
The red-headed woodpecker is one of my favorite birds, due in part to its striking combination of red, white, and black plumage (and they have a personality to match their plumage). In winter they should be called “acorn woodpecker” since at this time of year they have forsaken their summer diet of grubs and other insect foods and switched to a meal plan of acorns. The laurel oak acorn crop sought after by the woodpecker varies from year to year and the red-head in effect becomes a winter vagrant tied to acorn production. It searches the southern landscape for those oak forests with acorns of the right size – typically laurel oak, Nuttall’s oak, willow and water oak, cherrybark oak, pin oak, and others. Most of these species belong to the red oak group, reach greatest abundance in bottomland forests, and have acorns about half-an-inch long.
The Western Boundary Road (we use to call it the Upper Clubhouse Road since there was an old hunt clubhouse from the 1950s, now gone, at the end of it near Cooks Lake) has perhaps the densest concentration of laurel oaks in the park and I sometimes think of it as the “red-headed road.”
In some years at Congaree the striking woodpeckers are nearly absent; in others, very abundant. As an example, in previous years along this same route I had one red-head in 2007, none in 2003, none in 2000, two in 1996, and none in 1993. However, 1994 and 1995 were two good back-to-back woodpecker years with 25 and 30, respectively, counted. My best red-headed count on this route prior to 2013 was in 2001 with 50, followed by 1998 with 35 birds. Since 2001, red-headed woodpecker counts at the park leveled off to low and moderate numbers until the winter of 2013, when numbers rose dramatically to 146.
When comparing bird numbers between years for such things as the CBC, it is necessary to convert the figures to a number based on a unit of effort, in this case birds per party-hour, since the number of observers changes from year to year and more observers will result in seeing more birds of the same species. Using birds per party-hour shows that 1998 was by far the best winter for red-headed woodpeckers in the twenty-two history of the Congaree CBC with 3.4 birds per party-hour, a nearly 42% increase over the next highest figure of 2.4 red-heads per party-hour in 2001.
Surprisingly, we see no wood ducks today. Last year the sloughs and flats were full of water, along with a bumper crop of laurel oak acorns relished by the ducks (and woodpeckers) and we counted 30 woodies. American robin numbers are down this year too, with only 13, and attributed to the poor crop of American holly berries (last year’s numbers were 45).
We stop for lunch at our usual spot, the big sandbar on the river south of the junction of Western Boundary Road and the River Trail. It’s a nice change of scenery after spending hours walking through the forest, and a good location to spot a passing bald eagle, kingfisher, anhinga, cormorant, mallard, teal, or other river fowl.
Although the main purpose of the CBC is to get outdoors and have fun, the wealth of data generated over the past century and more has not escaped the notice of scientists who have mined the enormous data set (now online) for years to determine population trends, changes in distribution, and other indices of bird population health.
The Congaree CBC has compiled some impressive nationwide bird numbers. In 2013 it had the highest tally of pileated woodpeckers in the country with 105; it also had the highest count east of the Mississippi River for ruby-crowned kinglets with 508. In 2012 it was again the country’s leading location for pileated woodpeckers with 150; was in first place east of the Mississippi River for hermit thrushes with 126; and number two in the country for yellow-shafted flickers with a whopping 316. In 2011 it led the country for the number of yellow-bellied sapsuckers with 101 and was in second place for yellow-shafted flickers with 227. I’m convinced that Congaree National Park has the densest concentration of woodpeckers within the National Park system and certainly one of the densest anywhere in the country.