Science Alert reports:

Only some animals are known to fathom object permanence – the idea that something still exists even when it’s out of sight.

Oriental pied hornbills (Anthracoceros albirostris) are one of the few with an advanced understanding, a new study confirms. It’s a clever skill that comes in handy when nesting females seal themselves out of sight in tree hollows, relying on their mate to bring them food.

To lay and tend to their eggs in safety, female Oriental pied hornbills brick themselves into their refuge with dollops of mud, poop, saliva, fruit, and bark. They leave only a narrow slit for the males’ food deliveries.

For any offspring inside to survive, male hornbills must understand that their mate still exists even when they can’t see them.

“From an evolutionary perspective, the ability to represent other animals and objects when they are out of sight provides great adaptive advantages in activities such as foraging and avoiding predation,” National University of Singapore psychologists Ruitong Yao and Elias Garcia-Pelegrin explain in a new paper.

Yet, aside from notoriously clever corvids and cheekily smart parrots, no other birds were previously known to have object permanence to the same extent as primates. While other bird species have been tested, they only made it to stage four of the six developmental stages seen in human children. [Continue reading…]