Observations on Some Maritime Forest Spiders 

 of Four South Carolina Barrier Islands 



L.L. Gaddy 



Route 1, Box 223, Walhalla, South Carolina 29691 



ABSTRACT. — Quantitative observations on the seasonal abundance 

 of 22 species of araneid orb weavers and general observations on five 

 non-orb weaver species were made on four South Carolina barrier 

 islands. Data collected along transects revealed that 5 of 22 orb weaver 

 species matured in spring, 8 in early summer, 7 in late summer, and 2 

 in autumn. The greatest number of mature individuals of all orb 

 weaver species was found in early summer, but the greatest number of 

 species matured in late summer. Araneus bicentenarius, thought to be 

 rare, was found on all four islands. 



INTRODUCTION 



The spider fauna of the outer coastal plain of the Carolinas is rela- 

 tively unknown. Barnes (1953) and Barnes and Barnes (1954) studied 

 the ecology and species composition of spider communities in non- 

 forested maritime communities near Beaufort, North Carolina but did 

 not deal with the maritime forest. Berry (1971) discussed the seasonal 

 distribution of many of the species found on barrier islands, but his field 

 work was done in the Piedmont of North Carolina, an area climatically 

 different from the barrier islands of South Carolina. 



Maritime forest is the dominant vegetation cover type on the 

 barrier islands of South Carolina, where live oak, Quercus virginiana; 

 laurel oak, Quercus laurifolia; palmetto, Sabal palmetto; southern magno- 

 lia, Magnolia grandiflora; and various pines (notably Pinus taeda and 

 Pinus elliottii) dominate the canopy. Red bay, Persea borbonia; yaupon 

 holly, Ilex vomitoria; American holly, Ilex opaca; and palmetto are the 

 most commonly encountered species in the understory and shrub layers. 

 The canopy and understory are extremely dense, with nearly 100 

 percent coverage; the shrub layer's average coverage, on the other hand, 

 is low, varying from 10 to 50 percent. The coverage in the herbaceous 

 layer is usually less than 10 percent. 



From February to November 1979, monthly observations and 

 collections were made along transects on each of four South Carolina 

 barrier islands — Bulls, Kiawah, Capers, and Hunting islands. These tran- 

 sects, which averaged approximately one kilometer long, were walked at 

 least once a month between the hours of 0800 and 1700. All orb webs 

 and retreats between ground level and 2.7 meters high were checked for 

 adult spiders. The total number of individuals of each sex was recorded. 



Brimleyana No. 6: 159-162. December 1981. 159 



