Foraging flocks of spiders

Abstract

1. The prey capture efficiency of each individual in a Cyrtophora citricola colony is dependent on time (Fig. 1), total colony size (Fig. 1), and the spider's position within the colony (Fig. 2). 2. Aggressive approaches by orbless individuals within the colony appear to concentrate on the positions within the matrix of webs that have the highest capture efficiency (compare Figs. 2 and 5). 3. The incidence of avian attempts at predation and/or cleptoparasitism increases directly with colony size (Fig. 4), which indicates that the conspicuousness of the colonies is a disadvantage to the spiders. 4. Resource division is evident in the one mixed-species aggregation observed. Sticky-orb spiders (Leucauge spp.) take the same size prey as C. citricola (Fig. 3), but forage during the day when C. citricola is least active. Tangle-web spiders (Argyrodes spp.) capture prey in significantly smaller size classes than C. citricola capture (Fig. 3).