{"fact":"Rooks, a type of crow, have demonstrated the ability to understand that objects continue to exist even when hidden, a skill called object permanence.","context":"One rook demonstrated full OP (Stage 6b, multiple invisible displacements), whereas other individuals varied, attaining between Stages 5a (single visible displacements) and 6a (single invisible displacements).","source":"Francesca M. Cornero; Nicola S. Clayton, Object permanence in rooks (Corvus frugilegus): Individual differences and behavioral considerations, 10.3758/s13420-024-00637-0","index":636}