Concept learning is a learning mechanism allowing categorizing instances into broad categories based on their shared physical features or relationships, such as size (smaller/bigger) or position (below/above). Therefore, it remains unknown whether concept learning can occur in nature between coexisting species, specifically in the context of interspecific social information use. Here, we use a field experiment to test whether pied flycatchers can perceive relational concepts when using an experimentally manipulated extended phenotype of a great tit as information. We test whether flycatchers use the relative size difference of abstract symbols on tit nests and manipulated tit clutch sizes as information in their own nest-site choice. Our results suggest that pied flycatchers can perceive relational concepts, but overall flycatcher information use is complex, depending particularly on the physical and extended phenotypes of the great tit. The ability to conceptualize in decision-making facilitates adaptation to novel environments and may occur in a broader set of species and circumstances than currently understood. While we cannot completely exclude an alternative explanation of stimulus generalization (i.e. choice of the symbol with absolute surface area closer to that of the demonstrator symbol area), the context dependency of pied flycatchers’ likelihood to copy or reject the great tit’s decision suggests they most likely use more complex learning strategies than fixed stimulus generalization. Animals often rely on social information – decisions made by other individuals and the consequences of those decisions – also from other species when making important decisions affecting reproductive success and survival. However, the mechanisms underlying information acquisition, and the decision-making remain insufficiently understood. Many animals possess the capability for learning relative differences between objects (concept learning), which could play a pivotal role in social information use. Such ability to apply a learnt concept in a novel context allows animals to rapidly adapt to new environments and circumstances, which enhances individual success. Our study suggests that birds can learn concepts from other species through social information use in nature. This implies that concept learning may be more widespread in species interactions and adaptive decision-making than previously recognized.
Hämäläinen et al. (Tue,) studied this question.