Date of this Version
Miller, A. 2023. Aggregating Prey Lowers Handling Time Costs in Wolf Spiders. Undergraduate Honors Thesis. University of Nebraska-Lincoln.
Population dynamics for predators rely on their foraging abilities, which is supported most efficiently through optimal foraging behaviors. Development of foraging models, specifically the type II functional response, has allowed theoretical ecologists to estimate generalized foraging parameters for a considerable number of predator-prey systems. The assumptions of the type II functional response include that its parameters act independently from prey density, but further understanding of the predation process and adaptive predator behavior may suggest how the parameters of this model rely on the abundance of prey. Here I explored individual variation in wolf spider handling times associated with prey availability. I estimated individual times spent handling prey from video footage and evaluated the link between handling time, prey concentrations, and the propensity to accumulate multiple prey into a “meatball”. I found that meatballs contained more prey as prey were more available, allowing spiders to spend less time handling each prey captured. The formation of meatballs, however, allows spiders to escape some time cost of prey processing, permitting greater prey acquisition. This behavior also conflicts with the typical assumption in functional responses that searching for and handling prey are mutually exclusive activities. By discerning the factors that change handling time, we can more accurately predict foraging behavior and improve our understanding of why predators make the decisions that they do.
Key words: functional response, wolf spider, foraging, animal behavior