Biological principles underpinning Jaguar ABM

After some careful consideration of the need for a good biological foundation to my ABM, my supervisors and I agreed to implement some well-known population dynamics theory into key processes of the way the model and the agents undertake tasks.

Key factors: the jaguars - how they decide when and how often to move, and how they consume food across the landscape, and the food itself - food represents prey species and how will this respond to consumption?

Some sample prey species shown here, armadillo, coati, kinkajou, white-lipped peccary.

 


For my agents (jaguars), the key factor governing the way they move in the model is energy. Starting from an initial maximum energy state, they 'use-up' energy in a similar way to calorific expenditure in real animals. Moving and simply existing causes a steady loss of energy. Agents however need energy to survive and so must replenish this lost energy by consuming food. In this respect, low energy creates a greater need for the agent to change location to find an alternative, and potentially greater, food source. But of course real predators suffer a density-dependent relationship with prey and so based on some estimate of attack rate, a, handling time, b, and prey density, N, agents consume food based on the Holling Type 11 response:

Prey must then respond to being consumed, and are considered to regenerate according to a standard logistic growth function:

where, r is the intrinsic growth rate, K is carrying capacity and N is current prey density. For simplification, all prey species have been combined into a single food source and evenly distributed across the landscape, with K varying only with habitat type.