ame study Cyclosa argenteoalba Bosenberg & Strand 1906 was compared with C. octotuberculata. This species does not use debris for camouflage in the web and correspondingly was found to have a much shorter average residence time (Table 1). Even in certain spiders that do not recycle web proteins, predation during relocation has been found to be a major cost that favors long residence periods. Only 60% of desert widow spiders, Latrodectus revivensis Shulov 1948, survived relocation, far outweighing the material cost due to loss of silk (Lubin et al. 1993).
Like the desert widow spider mentioned above, the remaining orb web species with long residence times, P. noblei and Tetragnatha elongata Walckenaer 1842, are primarily nocturnal. Nocturnally active spiders largely avoid the dangers of being exposed in a web by day, but still require a strategy to avoid predation during this time while the majority of predators are active. Some, like L. revivensis, hide in a retreat that may offer a physical barrier against some predators as well as concealing the spider; other taxa, such as these Poltys and Tetragnatha Latreille 1804 species, rely on camouflage. This camouflage is manifested both in coloration and shape. Tetragnatha are elongate and usually lie on vegetation with legs extended linearly, blending in with the twig or leaf, while Poltys sit on the side or end of a twig with legs tucked in, appearing like a broken twig end or a dead leaf bud. Voluntary relocation would take place during the night, so one cost is loss of foraging time. But for these spiders the main danger in moving from a known "safe" web site may be the risk of not matching the substrate at a new, unknown, site and thereby becoming easily visible to a predator.
[FIGURE 3 OMITTED]
Movement strategies of spiders in different age classes are provided by the long-term results of the present study (Figs. 3a-c) and the seasonal analysis (Tables 2a, b). For P. noblei, the non-random pattern of residence of Small spiders compared to the apparently random pattern of Large spiders suggests that the risk associated with relocation increases as spiders become larger and thus more reliant on effective camouflage. Such changes in foraging patterns with age due to changing costs were predicted by Janetos (1982b). This changing relationship between efficient foraging for growth and the need for camouflage can also be seen in the seasonal shift in moves in and out of web sites. For P. noblei a general strategy is to move in spring and summer when rapid growth is occurring, but by autumn many spiders are settling into sites where they will remain until spring (Tables 2a & 2b). Spring is a time of high mobility in all size classes. In fact, 100% of Small spiders end their residence during spring, even though only 60% begin a residence during this period. The 40% discrepancy in numbers will be largely due to the maturation of males. Other size classes also show a high percentage of spiders moving out of established web sites (i.e., ending a period of residency) in spring. This may be to seek a prey-rich web site after a long period of low prey availability over winter. Indeed the model of Leclerc (1991) based on observations of the linyphiid Tenuiphantes flavipes (Blackwall 1854) predicted differential optimal strategies with regard to staying or moving dependent upon the spiders' body fat reserves. So many spring movements could also indicate that staying too long carries risks that balance the dangers of moving. Predators may learn to associate a build up of silk lines with the likely presence of spider prey. For instance, it is often unclear what cue initiates the cryptic prey flushing behavior reported in Sceliphron laetum (F. Smith) (Coville 1987), a technique observed in the capture of Poltys spiders by this wasp (R. Raven pers. comm.).
The long-term figures for Poltys residence times are overestimates to some extent. In particular, many spiders may have been missed because they both arrived and left a web site between samples and this factor would make the long term av