Animals may consider both biotic and abiotic factors in foraging site choice. Among the biotic factors, food availability and predation risk are two widely reported important factors in determining foraging site fidelity. Their earlier investments, such as those retreat-building species’ efforts in retreats construction, however, have been largely ignored. The orb-web spider Cyclosa monticola constructs a long column of masquerading detritus decoration in its web for predator avoidance purpose. This detritus decoration also functions as a retreat. However, the role of the detritus decoration for its foraging site fidelity is unknown. By manipulating three factors, presence of detritus decoration, prey availability, and predation risk to the spider webs in the field, we show that the self-constructed detritus decoration is as important as prey availability and predation risk in mediating web site fidelity. In addition, the web area also has a significant impact to the foraging site fidelity of the spider, those with larger webs were more likely to leave after being manipulated. However, other factors such as spider body size, decoration length, and rain all have no significant impact. Our study may strengthen the current understanding of the movement and foraging of animals, especially those building retreats.

Field observations