Object permanence, the concept that objects continue to exist even when they are out of sight, is a cognitive ability that is not common among animals. However, Oriental pied hornbills (Anthracoceros albirostris) have been identified as one of the few species with an advanced understanding of this concept. This new study confirms that these birds possess a clever skill that is crucial for their survival, especially during nesting periods.
During nesting periods, female Oriental pied hornbills exhibit a unique behavior where they seal themselves out of sight in tree hollows to lay and tend to their eggs. To ensure their safety and the safety of their offspring, these females brick themselves into their refuge using mud, poop, saliva, fruit, and bark. They leave only a narrow slit for their male counterparts to deliver food. This behavior requires the male hornbills to understand that their mates still exist even when they cannot see them.
A team of researchers led by National University of Singapore psychologists Ruitong Yao and Elias Garcia-Pelegrin conducted a study to test the object permanence skills of six Oriental pied hornbills. The researchers taught the birds to indicate the location of a visible treat with a peck and then presented them with a series of challenges that tested their understanding of object permanence, progressing through increasingly difficult levels.
All six birds were able to demonstrate an understanding of visible displacement, indicating the cup where the treat ended up. However, only three of the hornbills were able to advance to the final stage of object permanence – invisible displacement. In this stage, the birds had to infer the location of the treat without directly observing its movement. The birds that successfully completed this stage showcased an integration of complex cognitive skills such as memory, spatial reasoning, and logical inference.
The researchers note that the three birds that did not progress beyond the fifth stage of object permanence had no breeding experience. This observation raises questions about the role of experience in the development of advanced cognitive abilities in birds. The study’s findings also highlight the advanced cognitive capabilities of Oriental pied hornbills and suggest that they may possess intelligence comparable to that of apes.
The study on the object permanence skills of Oriental pied hornbills sheds light on the cognitive abilities of this bird species. The findings suggest that these birds may have been overlooked in terms of their intelligence and cognitive capacity. Further research is needed to explore other cognitive abilities in Oriental pied hornbills and understand how they compare to those of other highly intelligent bird species like parrots and corvids.