Vertebrate Fauna of North Carolina Coastal Islands: II. Shackleford Banks

Engels, William

Shackleford Banks is an off-shore bar, submarine in origin, hence its fauna and flora were acquired, subsequent to its emergence, through over-water invasion. The island is about 8 miles long, 1/4 to 1/2 miles wide; it lies 2 to 5 miles off the mainland coast of North Carolina. In form and general topography it is a typical barrier-beach island but it has suffered drastic changes in its vegetational cover, and in its form, in the past half-century. It was formerly wooded in its entire length; this woodland, covering about 1250 acres, probably was composed chiefly of live oak, red cedar, yaupon holly and loblolly pine. The inner shore, on the eastward half of the island, was bordered by salt marshes; the only other grassland consisted of the sea-oats covering the dunes back of the outer beach. Due laregly, as this writer believes, to naturally initiated erosion of the outer- beach, to hurricane floods, and to drifting sand, the woodland has been reduced to approximately 180 acres, about 15 percent of its original area. It has disappeared entirely from the eastward half of the island, where it has been replaced by grassland; some of the salt marsh has also been converted into a dry grassland through the deposition of wind-borne sand from the outer beach. On the westward half of the island, where generally higher elevations occur (10 to 20 feet), a sand wall is advancing across the island, and burying the woodland. Here the outer half of the island has been converted into a barren, sandy wasteland, on which stand the skeletons of red cedars. Between the sand wall and the inner beach, in a strip about 2 1/2 miles long and 180 to 400 yards wide, stands the remnant of the woods and thicket-woodland, occasionally intersected by marshes extending in from the inner beach. There are now probably no permanent fresh-water pools on the island. In September, 1933, a hurricane flood cut a new inlet across its eastern end, separating Shackleford Banks from Core Banks and Cape Lookout. The island has been uninhabited for some years, although formerly it supported a small population of fishermen; it has a relatively large population of semi-feral sheep, goats, pigs, cattle and horses. Shackleford Banks has a moderately temperate climate, with an average continuously frost-free season of 269 days. Tropical storms of hurricane intensity hit in upon, or pass close by, the North Carolina coast with an average frequency of 1 every 4 years. Since 1879, two of these, because of their intensity and diameter, were classed as "great" hurricanes; they occurred in August 1885 and September 1933. At least 34, and probably not more than 40, species of land vertebrates-exclusive of shore- and aquatic-birds-occur on this island, as against about 186 species on the adjacent mainland. Only about 15 percent of the amphibians of the mainland occur on the island, not more than 20 percent of the land birds (perhaps only 15 percent), and about 25 percent of the reptiles and mammals. The amphibian fauna consists of five frogs and toads, representing 5 anuran families; salamanders appear to be absent from the fauna. There are 4 lizards, at least 6 snakes, and at least 2 turtles. Conspicuous, definitely determined absentees include the oak-toad (B. quercicus), and poisonous snakes of the genera Crotalus and Agkistrodon; only one blue-tailed skink (Eumeces), of the three species occurring in the coastal plain, has reached the island. One of the snakes (Rhadinaea) here reaches its northernmost limit of distribution. Apparently only 12, but perhaps 16, species of land birds breed on the island; of these, only 8 occur in considerable numbers, 4 of these species being primarily grassland birds, and 4 belonging to the thicket-woodland. One of the latter (painted bunting) here reaches its northernmost limit of distribution. Conspicuous absentees include warblers, mimids, the towhee, and the seaside sparrow, all of which occur in numbers on adjacent islands. There are definitel

Vertebrate Fauna of North Carolina Coastal Islands: II. Shackleford Banks

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