Spider webs as habitat patches -: The distribution of kleptoparasites (Argyrodes, theridiidae) among host webs (Nephila, tetragnathidae)

Most adult golden orb weavers (Nephila clavipes) have kleptoparasites of the genus Argyrodes in their webs. The kleptoparasitic load correlates positively with web size. Clustered (interconnected) webs have a more predictable number of kleptoparasites than do solitary webs, but there is no difference in the mean number of kleptoparasites between the two. From the view of the kleptoparasite, host webs are habitat patches or islands. Isolated webs show characteristics of small patches, where web size is a poor indicator of kleptoparasite number and variation is high. The distribution of kleptoparasites in clustered webs, on the other hand, seems to fit the "ideal free distribution" where web size nearly entirely predicts kleptoparasitic load. Thus clustered webs, as a habitat patch, are more than merely the combination of their parts. The predictability of kleptoparasite load in clustered webs may be a function of the stability (longevity) of those habitat patches, and ease of colonization, as neighboring webs act as sources.