Context-dependent resource choice in a nest-building fish

When making decisions, individuals can be influenced by both the range of options available to them and intrinsic factors, such as their own body size or condition. The current understanding of the topic comes mostly from studies of foraging behaviour and mate choice, whereas other fitness-related decisions have been the subject of much less attention. Here, we investigated how the number of available options, along with body size and condition, affect the nesting resource choices of male sand gobies, Pomatoschistus minutus. The results show that resource choices were not affected by additional choice options (i.e. binary versus ternary choice situation) or the body condition of the chooser, whereas resource size, resource type (i.e. whether choices were between arched or flat resources) and body size did have an effect. In particular, while larger nesting resources were chosen more often in most situations, this pattern was stronger among larger males and when the resources had a flat, rather than arched, shape. Indeed, in the case of arched resources, the medium size category was more popular than the smaller and larger ones. Together, the results show that both intrinsic and extrinsic factors can influence important behavioural decisions over resource choice.