The Innovative Bird: Contextual Determinants and Underpinning Mechanisms of Innovative Foraging

The tendency to invent new behaviours or use pre-existing ones in novel contexts is a primary source of behavioural plasticity. Over the last two decades substantial progress has been made in our understanding of the adaptive benefits of innovativeness in birds. As a result, behavioural innovations are now considered to play a significant role in adjustment to novel and changing environments. Research on proximate mechanisms, however, has progressed more slowly. Whereas one line has pursued the idea that foraging innovations arise through random motor variability combined with persistence and associative learning, the other has investigated the extent to which animals deploy higher order cognitive processes, such as causal reasoning and inference, to exploit new foraging opportunities. In this chapter, we review the findings from macro-ecological research on innovation with a particular focus on the view that innovative foraging behaviour provides a direct measure of general avian intelligence. We then explore the contributions, but also the shortcomings, of experimental research on innovation. We begin by developing the rationale behind experimental methodologies and review evidence that innovative behaviour is influenced, not by limits on information processing capacity, but rather by factors that influence the rate at which new environmental information is encountered. We then consider the question of whether inter-individual variation in innovation propensity is repeatable, heritable, and associated with higher reproductive success, pre-requisites for the evolution of cross-taxon variation in innovativeness. Finally, we consider three possible mechanisms of innovation and argue the case that random motor variability is central to understanding how innovative behaviour arises. We conclude by proposing a model of innovation and identifying future research directions.