Does Partial Consumption Help Foraging?

Abstract

In this work, we consider partial consumption of food by a forager in presence of a threshold energy level. The forager considered here can survive for $S$ steps without food, namely the survival time. The threshold limits the consumption of food in such a way that, the forager will only consume food, whenever its energy is below the threshold $k$. Due to partial consumption of food, a site containing food may not always be fully depleted, which in turn helps in increasing the lifetime of the forager. It has been observed that, in our case, the lifetime always increases with $k/S$, although there is a transition threshold $k^*$ below which the increase of lifetime is rapid and above is slow. The transition threshold $k^* \sim \sqrt{S}$. The lifetime $\tau$ shows a power law behavior as $\tau \sim S^{\beta}$. For $k/S=0$, the value of $\beta$ is $1.331$, it then jumps above $2$ and decreases gradually to $1.833$ with increasing $k/S$. Other important quantities like number of revisits to a site, food statistics etc. have been studied and some interesting scaling behaviors are observed. Although, survival for each time unit requires, on an average, the consumption of one unit of food, the food consumption is not the only factor to control the lifetime of the forager. It has been observed that, the strategy in terms of threshold energy and partial consumption affects the lifetime in a positive way. The collection of sites either fully or partially depleted of food after the death of the forager shows a crossover behavior for $k/S \sim 0.5$.