Forager Searching Patterns, Environmental Conditions and Food Spatial Distribution

Inon Schärf - PhD Candidate

Dr. Ofer Ovadia - Supervisor

Searching behavior is an active process adopted by an individual organism when attempting to find food, mating opportunities, oviposition site, nesting site, and new habitats. Because such resources are vital to every organism, an accurate assessment of these resources in combination with an efficient searching behavior should increase the fitness of the organism. Furthermore, studying searching behavior is crucial for the development of theories in evolutionary biology such as optimal foraging, and models on Bayesian foraging, mating strategies and oviposition strategies. Inon is using both theoretical and empirical tools to test if and how animals change their searching tactics in response to food quality and spatial distribution, and how such a response is influenced by the density of conspecifics and by the individual body condition and innate capabilities such as attack radius or handling time. The theoretical component consists of simulation models, written in MATLAB. The first model evaluates the efficiency of predators using different foraging modes, active predation vs. sit-and-wait predation, under different conditions. The second model uses a genetic algorithm to optimize searching tactics of a forager searching for hidden prey in different food spatial distributions and having different constraints and capabilities. Two alternative model systems are used in the empirical study: ground beetle species searching in a 9 squared-meter arena and several land snail species searching on 1 squared-meter thick paper. Movement patterns are analyzed using correlated random walk models and fractal dimensions.  A concluding model will be developed to predict the probability distribution patterns of species as a function of landscape heterogeneity.

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