The costs of moving for a diurnally cryptic araneid spider
In orb web spiders that recycle webs and thus minimize the material costs of web relocation, the characteristics of their temporal movement patterns between web sites can be used to examine otherwise hidden costs. Previous studies have shown that one such cost is the extra risk from predation. An unusually long average residence time at web sites is one indicator of cost. In some cases the pattern of movements also appears to be indicative of high costs, similar to those experienced by spiders that do not recycle web proteins. Nocturnal Poltys noblei Smith 2006 (Araneidae) spiders are heavily reliant on good camouflage in their exposed daytime hiding positions. Thus the risk of moving to an unknown site where the spider may not match its background may impose a large cost on relocation. The temporal pattern and frequency of relocations of P. noblei in northern Sydney are compared to those reported for other orb web species. Poltys noblei, on average, is found to have a long residence period, and the pattern of movement of larger individuals in this species is found to be random. These data support the idea that moving is costly for this species. Finally, the seasonal timing of movements is examined for P. noblei. It is found that most spiders relocate in spring but it is unknown if this is to seek a better web site or for the spider to avoid predation.