Metepeira datona is the commonest orbweaving spider on very small islands of the central Bahamas. Where studied, large spiders built higher, wider and deeper webs than did small spiders, and they oriented webs modally so as to expose the least surface to the prevailing winds. About 17% of webs contained more than one spider, but large females almost never shared webs with one another. All individuals combined, and sex-age classes individually (including large females), were significantly more clumped in 2-dimensional space than random. Moreover, potential web sites for large females were about 10 x as common as occupied sites, were dispersed randomly, and were significantly less clumped than occupied sites. We conclude that a rudimentary coloniality exists and speculate on predator defense, prey capture, sharing of silk and structural support as adaptive functions.