Optimal Foraging Theory and Measure Giving Up Density (GUD)

Introduction

Ecologists have, over the past, argued that natural selection considerably optimizes animals’ foraging behavior. As asserted by Pyke (2019), foraging refers to the approaches used by animals to obtain and eat their food. It includes hunting for prey and searching for plants and depends on the environment and species. Animals’ foraging behavior significantly predicts the survival of animals. According to this theory’s proponents, natural selection favors tactics that balance the importance of a particular food, such as nutrients and energy, with the cost of acquiring it, such as the risk of predation and energy (Pyke, 2019). Various researchers have tested optimal foraging and giving-up density (GUD) in animals.  

Optimal Foraging Theory (OFT), as recorded by Abdulwahab et al. (2019), is an ecology model that helps biologists and ecologists to predict how animals behave when searching for food. According to these authors, foraging is a practical approach to the survival of every animal in an ecological niche. Abdulwahab and his co-authors sought to offer an empirical understanding of some of the factors that affect the perception of habitat quality and foraging behavior by animals. Therefore, they investigated how granivorous bird species perceived prediction risk concerning different microhabitat types and habitats, food types in the Nigerian Aurum Forest Reserve, and time of day.

The researchers conducted three-month field experiments to measure the amount of food left in the Nigerian Aurum Forest after birds failed to forage (giving-up densities). They also measured how GUD differed with microhabitat types, food types, time of the day, and habitat types. Abdulwahab et al. (2019) reported no significant difference in giving-up densities across all habitats. Nevertheless, they found out that that there was a substantial difference between microhabitats and GUD. Fewer food remains were recorded in cover microhabitats than in open microhabitats. This is because granivorous birds patch more in the cover. Across all habitats, birds searched for food more in the morning hours than in the evening.

Abdulwahab et al. (2019) concluded that foraging decisions significantly predicts the quality of a habitat as perceived by birds.

In an ecological niche, animals have evolved to increase their energy uptake to patch for more or sooner food (Chandel et al., 2021). The authors measured the hypothesis that exiting the current patch among Columbian pigeons can be delayed by providing them with a choice between multiple and progressive schedules. On the multiple schedule, a colored light indicated the required number of pecks for food. On the progressive schedule, escalating number of pecks predicted food access. The researchers observed birds’ behavior in the two schedules. Pigeons switched from multiple schedules to progressive schedule at any time. The researchers found out that pigeons switched to the multiple schedule from continuous progressive schedule earlier than they would have been optimal.  Chandel et al. (2021) concluded that the indication to switch on the progressive schedule was the required number of pecks for the next reinforcer as well as the more overall signal of the difficulties in obtaining reinforcement.