NATURAL HISTORY OF THE KING RAIL 



29 



giant cutgrass formed 52 percent of the marsh vegetation, arrow- 

 arum 36 percent, and cattail 12 percent. 



For the actual census, the entire marsh area, as shown on U.S. 

 Geological Survey maps, was blocked off into 64 primary sampling 

 units, each a 630-foot- wide transect extending from the edge of the 

 river to the land. Each transect was divided into 10-acre plots, the 

 number in a transect depending upon the width of the marsh at that 

 location along the river. 



Ten of the 64 transects were randomly selected as primary sampling 

 units, and one 10-acre plot from each was chosen for censusing. At 

 least 1 hour between 5 and 8 a.m. or 5 and T p.m. during the period 

 April 10 through 12, 1961, was spent in each plot counting calls. 



The number of male King Kails in a transect was estimated by 

 multiplying the number of 10-acre plots in that transect by the num- 

 ber of birds heard in the census plot. The estimated total of 755 males 

 in the 3, 000- acre marsh was derived by multiplying the average num- 

 ber of birds per sample transect by the total number of transects. The 

 density estimate of 25.2 male birds per 100 acres was calculated by 

 dividing the total population by 30 (the number of 100-acre units in 

 the 3,000-acre marsh). Since some of the calling King Eails were 

 undoubtedly already mated, and most of the others would be eventu- 

 ally, the average number of breeding rails per 100 acres could be 

 inferred to be 25 pairs (table 3). 



Sampling indicated that the density of the King Kail population 

 was higher at Georgetown in the Pee Dee Kiver marshes than several 

 miles up river along its tributary, the Black Kiver. One 10-acre plot 

 at Georgetown had six calling rails, and four other plots had four 

 each. None of the Black Kiver plots had more than two rails. The 

 higher density at Georgetown could be attributed to the higher pro- 

 portion of red- jointed fiddler crabs {Uca minax). 



Savannah National Wildlife Refuge 



The Savannah National Wildlife Kefuge in South Carolina and 

 Georgia, near Savannah, is about 25 miles upriver from the ocean on 

 what was formerly a rice plantation (fig. 13) and is divided by the 

 Savannah Kiver. The larger acreage is on the South Carolina side. 

 Its marsh is the fresh tidal type, with a tide which rises about 1 foot. 



Giant cutgrass is the dominant vegetation of much of the marsh 

 on the refuge. The old growth of cutgrass forms a nearly pure stand, 

 and has an average height of about 5 feet, but will average higher 

 when the new growth matures. Arrow-arum, dotted smartweed, and 

 swamp smartweed {Polygonum hydropiperoides) are scattered about 

 the marsh, particularly along the edges and on high spots. There are 

 numerous small holes made by the red- jointed fiddler crab, an impor- 

 tant food of the King Kail, along the tidal creeks and edges of the 

 marsh. While making a survey of King Kail populations in April 



