Predator agents

Like in the original symbiants using a scalar signal field, I want to introduce predation. I'd like it to be a little more nuanced then the way I did it before, just spawnings new factions and weighted randomly selecting a food source based on total number of agents belonging to each type of food. This may require a little more thought. I can get a basic system up now. Maybe all agents can choose to be a predator based on how recently they've found food?