Investment decisions in grey squirrels: the role of future discounting and executive control (Ref: 4264)

Investment behaviour necessarily entails planning for the future. It can take many forms across species, and requires some degree of executive control: investors need to inhibit immediate use of an asset to store it away for a future which is, inevitably, uncertain. Investment decisions provide a window into an animal's expectations about the future and can be expected to vary with life-history parameters.

Grey squirrels are an ideal model species for studying investment because they are natural and prolific investors, storing nuts during times of plenty to provide a reliable source of food when it is scarce. Squirrels not only decide whether to cache or eat a food item, but caching itself involves a series of predation and pilferage risk trade-offs, which co-vary with food value. As such, investment decisions directly reflect future discounting and ought to be tightly linked to executive control.

Project Aims and Methods

This PhD project will investigate the role of future discounting and executive control in investment decisions made by wild grey squirrels, as part of a long-term field study of squirrels living on the University of Exeter campus. There are two key aims:

develop reliable assays of executive control in squirrels and record their investment decisions and outcomes in terms of successful food recovery, as a real-life measure of the costs and benefits of delaying gratification;

generate and test predictions of caching behaviour from integrative models that consider both optimal foraging (from the behavioural ecology tradition) and the cognitive mechanisms of discounting and executive control (from experimental/cognitive psychology).

By devising field experiments to verify abstract laboratory tests of executive control, the student will generate reliable measures of executive control in free-living squirrels and measure the outcomes of their natural investment decisions. The student will construct mathematical models of adaptive investment behaviour based on executive control and future discounting, to generate predictions that he/she will test by collecting experimental data on wild squirrels in the field.