Density of spiders (Araneae: Ctenidae) in Ivory Coast rainforests

To monitor the biodiversity quality of rainforest fragments in the eastern region of the Ivory Coast, the density of at least one important invertebrate group needs to be determined. This has been possible for nocturnal hunting spiders from the family Ctenidae using a novel combination of sampling and census techniques. The reflective characteristics of the eyes of these spiders meant that individuals were readily located using headlamps. Collections were made along transects (total length 5.5 km), adopting a distance sampling protocol. Density was estimated using distance sampling models. More than 2600 ctenids (15 species) were captured and identified. Seven of these species were present in sufficient numbers for density assessment. The combined density of these seven most common species in degraded forest fragments (0.124 m−2) was only half that in less disturbed forest (0.240 m−2). Ctenidae are a promising candidate for future monitoring of invertebrate groups in the rainforest.