Great white pelicans (Pelecanus onocrotalus) fail to use tools flexibly in problem-solving tasks

Although reports of animal tool-use are phylogenetically widespread, it remains rare in the wild. From the perspective of human evolution, this rarity was first explained by the cognitive demands associated with tool use. Recently, an alternative assumption, the tools are not often useful hypothesis, proposes that tool use is rare, because it is seldom more useful than the species' anatomical adaptations. At the same time, several species that do not use tools in the wild have shown the capacity for tool use in experimental problem-solving settings, which suggests a certain level of cognitive flexibility. Investigating whether habitually non-tool-using species are able to use tools flexibly is crucial to evaluate the predictions of existing theories on the evolution of cognition. In this study, we tested whether great white pelicans (Pelecanus onocrotalus), morphologically specialized fishers, for whose natural foraging tools are unlikely to be of use, were able to use tools in two problem-solving situations. In two tasks, the subjects were required to drop tools into an apparatus to gain access to a food reward. In Tool-use task 1, we tested the capacity of pelicans to show spontaneous tool-use behaviour. In Tool-use task 2, we assessed the birds' tool-using performance, before and after providing them with different kinds of information about the task's solution, that is experience with the functional features of the apparatus (platform-pushing group) and trial-and-error learning of tool-dropping behaviour (stone-nudging group). All subjects failed in using tools in Tool-use task 1 and only one individual in the stone-nudging group learnt to use a tool in the training phase of Tool-use task 2. Despite previous experience with the functional properties of the task, birds from the platform-pushing group did not exhibit tool-use behaviour or increased motivation towards the apparatus and the tools during the test phase. Although pelicans were not inhibited by morphological constraints to carry out the required tool behaviours, whether they lack the cognitive prerequisites for flexible tool-use remains to be further tested.

Automated summary

This study tested the tool-using ability of great white pelicans in the wild and found that most individuals failed to use tools successfully, with only a few learning to use tools under training conditions, indicating limited cognitive flexibility in this species.