String-pulling in the Greater Vasa parrot (Coracopsis vasa): A replication of capacity, findings of longitudinal retention, and evidence for a species-level general insight factor across five physical cognition tasks

Abstract

Spontaneous solving of an insight-based means-end reasoning task (the string-pulling problem) is observed in an adult male captive bred Greater Vasa parrot (Coracopsis vasa Shaw, 1812), with an efficiency of 66%, replicating previous work in a singleton context. This case report adds to the existing literature on this species by also demonstrating longitudinal retention, specifically the same bird was found to be able to re-solve the simple form of the problem after a period of seven years (the bird was first tested in 2013, and re-tested in 2020), with an efficiency of 43% (the difference between efficiencies was not significant, χ2 = 0.991, p = .319). In a second analysis, species-level data across five patterned string-pulling tasks involving 14 parrot species were reanalysed, revealing that the Greater Vasa parrot exhibited the greatest general competence among those evaluated. A ‘general insight factor’ (GIF) was also found across taxa, the loadings onto which exhibit positive and large-magnitude associations with the correlation between fission-fusion flocking intensity and indicator level performance (r = 0.831), and also positive small and modest-magnitude associations with the correlation between relative brain size and indicator-level performance, and the magnitude of average pair-wise species differences in performance across indicators (r = 0.219 and 0.365 respectively). Finally, the theoretical implications of these findings are discussed.