Feeding experience affects web relocation and investment in web threads in an orb-web spider, Cyclosa argenteoalba.

Orb-web spiders often relocate their webs when they assess a web site as prey poor. When a spider spins its web at a new site, it may not be able to assess the prey availability at the site accurately on the first day, owing to stochastic variation in foraging success, but it is gradually able to make an assessment. Therefore, a spider's foraging behaviour may change according to how long it has been at its current web site. To test this possibility, we conducted a prey removal experiment, with the spider Cyclosa argenteoalba, to compare the response to prey deprivation of spiders that were on new sites with that of spiders that had been at a site for several days. Spiders in both groups had a higher relocation rate than the natural rate, but more spiders in the new-site group relocated their webs. Spiders thus seemed to use previous experience of prey capture at a web site to decide whether to relocate their web. The total length of silk thread in a web was greater on the second day at a new web site than on the first. We suggest that spiders minimize their investment in web threads until they are certain that the web site is prey rich. Copyright 1999 The Association for the Study of Animal Behaviour.