Despite object categorization being an important ability for the survival of animals, the principles behind this ability have been only scarcely studied using wild-ranging, untrained animals. There are two basic theories of object categorization. According to the first theory, objects are recognized by the presence of key features such as the beak or eye (particulate feature theory). According to the second theory, the mere presence of these features is not enough and their spatial arrangement (recognition by components) plays a role as well.
Nela Nováková, Petr Veselý and Roman Fuchs from the Department of Zoology of the Faculty of Science USB studied which one of these methods of recognition uses the red-backed shrike (Lanius collurio). These singing birds are characterized by aggressive defense of their nests and are able to distinguish between different types of predators. The kestrel’s dummy with the interchangeable body parts (i.e., the species most commonly attacked by the shrikes) was used and the pigeon and the complete kestrel was used as a control.
The results show that the mere presence of key features may not be sufficient for reliable detection of a predator, which has resulted in birds rarely attacking altered dummies but being unwilling to feed their chicks in their presence. However, it cannot be demonstrated that shrikes use only one of the proposed methods to recognize a predator.
Nováková, N., Veselý, P., & Fuchs, R. (2019). Object categorization by wild-ranging birds in nest defence. Animal cognition https://doi.org/10.1007/s10071-019-01329-3