TEMPORAL AND SPATIAL SEGREGATION OF WEB-BUILDING IN A COMMUNITY OF ORB-WEAVING SPIDERS

The temporal pattern of activity and spatial distribution of six species of nocturnal orb-weaving spiders (Araneae: Araneidae and Tetragnathidae) were examined in coastal hedge vegetation in Israel. In Autumn, small spiders of all species built their webs early in the evening and progressively larger spiders put their webs up through the night. This activity pattern corresponded to the change in sizes of flying insects throughout the night. There was no interspecific segregation in time of activity. Spiders were highly clumped in space, but showed interspecific segregation only in web height. In Autumn, Nuctenea suspicax was the most abundant species, while in Spring Singa lucina predominated. During the latter season, spiders had two periods of activity: evening (at dusk) and morning (pre-dawn). Morning-active spiders had larger webs and larger clutches than evening-active spiders. As in Autumn, there was little interspecific segregation in time of activity or in spatial distribution. Spider removal experiments suggest that the timing of activity does not change following density reduction, but that individuals that were previously inactive may take advantage of the newly available spaces. The number of active spiders increased when sites for web attachments were added, supporting the hypothesis that space availability limits spider activity. The results are discussed in terms of the importance of niche partitioning in time and space.