Primary Source Material: Preliminary Survey for Spiders on Nevis, West Indies
Jo-Anne Nina Sewlal and Christopher K. Starr, Dept of Life Sciences, University of the West Indies,
St Augustine, Trinidad and Tobago (click here for Nevis spider photos)

During January 2006, we spent two weeks on the island of Nevis with the aim of collecting a substantial part of the spider fauna in a broad variety of habitats. Nevis is a compact oceanic island with an area of 93 km2, situated in the northern Lesser Antilles 17o10’N 62o35’W.  It is relatively topographically simple, with a gradual rise on all sides from the shore to a central peak at 985 m.  Nevis has range of natural and secondary habitats that include montane forest, elfin woodland, palm brake, grassland, coastal scrub, dry woodland and farmland. (Robinson and Lowery 2000).

Sampling took place at 14 localities dispersed throughout the island. Our main collecting method was through visual search, both at the ground level and above ground, including in shrubs and low trees.  We supplemented this with sweep-netting, especially of coral vine (Antigonon leptopus) and other roadside flowering plants that attract insects, which in turn attract spiders.  In addition, we searched many more cryptic microhabitats, especially under rocks and rotting logs.
Specimens collected were deposited in the Land Arthropod Collection of the University of the West Indies, St. Augustine, Trinidad and Tobago.

In nine habitat types, we collected a total of 29 species of spiders representing 12 families (Table 1).  Our brief exploration of the montane forest and elfin woodland on Nevis Peak was made under difficult conditions and yielded no spiders.

We found 16 of the 29 species each in only one habitat type (Table 1).  The most ecologically diverse species, by this measure, were the very abundant Gasteracantha cancriformis and Leucauge regnyi, recorded from seven and six habitats, respectively.  The garden habitat yielded the greatest number of species, 13, and the foothills and palm brake the lowest, each with two species.  More than half of the species were in the orb-weaving families Araneidae and Tetragnathidae.

Our collecting effort was not an exhaustive survey but an attempt to find a large number of species in a diversity of habitats.  Some of our quantitative comparisons are probably an artefact of this approach.  As an example, it is much easier and more pleasant to collect in a garden than in the steep-sided, densely-vegetated palm brake.  Even so, there is reason to expect tropical gardens to be very biodiverse, so that the high yield of specimens in this habitat is probably not misleading.  Similarly, we spent much less time in coastal scrub than in some other habitats.

A more important source of potential bias is in our collecting method, which was directed mainly toward species that can be seen under ordinary circumstances.  This undoubtedly accounts for the heavy preponderance of web-building spiders, especially of the orb-weaving families.  While our results represent a good beginning, the use of methods suited to collect leaf-litter-dwelling and other cryptic spiders can be expected to yield many additional records.

Click Here for Photographic Gallery of Nevis Spiders

Table 1: Observed habitat ranges of spiders on Nevis, West Indies. Genus names in quotation marks are of uncertain nomenclatural validity.