Food threshold territoriality in a water strider (Gerris remigis)

Foraging in groups of water striders (Gerris remigis): effects of variability in prey arrivals and handling times

“…In general, individuals of both genders maintained their positions in the stream and defended them against intruders, many of them for the entire duration of the study (5 weeks); they were hence territorial as described by both Wilcox and Ruckdeschel (1982) and Rubenstein (1984). This resulted in consistent long-term variability in foraging success among the group members, verifying an initial assumption of the model.…”

“…Wilcox and Ruckdeschel (1982) have demonstrated that territorial behavior may be observed within the limits of a critical lower food threshold (above which territoriality becomes economically profitable) and an upper threshold (above which exclusion of competitors is unnecessary). During the experimental periods, downstream individuals clearly had low average foraging success.…”

“…In natural streams individual water striders of both genders occupy consistent foraging positions that they may defend as territories (Wilcox and Ruckdeschel 1982;Rubenstein 1984). In some sections, such as where a current too swift for Gerris remigis drains into a wider pool where the animals tend to aggregate, this results in priority of access to prey items floating downstream for individuals further up front.…”

“…Rubenstein (1984) has shown that, during the mating season, individual Gerris remigis hold territories of different quality with respect to food and mate acquisition and that larger individuals tend to occupy better patches. Wilcox and Ruckdeschel (1982) have shown that such territorial defense is a flexible individual strategy that depends on the ratio of resource abundance to competitor density. Using a simple heuristic model, I intend to show how temporal fluctuations in resource supply additionally affect the foraging success of individuals with varying degrees of priority of access to the resource.…”

Experimental studies on water strider mating dynamics: spatial variation in density and sex ratio

“…In addition, dispersal patterns determine the range of local conditions experienced and thus the fluctuation and variation in mating patterns that determine the nature of sexual selection. Most previous studies on stream water strider mating dynamics have focused on single stream pools or on artificial pools (Wilcox and Ruckdeschel 1982;Wilcox 1984;Rubenstein 1984;Clark 1988;Sih et al 1990;Sih and Krupa 1992;Fairbairn 1993). Future work on the ecology of mating systems should take account of the multi-patch nature of the system.…”