Are Birds Really Birdbrains?

Leaving Cromar’s with a precious bundle of fish and chips covertly tucked in your jacket, you can only make it as far as the grassy viewpoint on the Scores before you — and your dinner — are caught in a perilous brawl with the beady-eyed pirates of the sky. With their insufferable squawking and indomitable pursuit of all things remotely edible, the evolutionary wonders of gulls, and birds more broadly, is probably not the first thing to cross your mind. 

Indeed, it must be acknowledged that these flying frustrations belong to the few animal species that survived the mass extinction of the dinosaurs 66 million years ago. It has been hypothesised that the meteor strike survival of avian dinosaurs may be attributed to their small size, faster breeding, varied diet, and, in particular, unique mechanisms of flight. The evolution of the avian brain that occurred between the time of dinosaurs to that of modern birds has been largely elusive, mainly due to a lack of fossil evidence. However, at the end of October, an article published in the scientific journal Nature presented the skull of Navaornis hestiae, a fossil bird which fills this 70-million-year gap. 

Palaeontologists from the University of Cambridge analysed the fossil — which was excavated from a site in the Brazilian state of São Paulo — using micro-computerised tomography (micro-CT) scans. While this method is a highly valuable tool for obtaining three-dimensional insights into bone structures, the exceptional preservation of the fossil itself also contributed to the achieved detailed analysis. Such high-quality preservation is rare, especially for avian skulls, and is likely due to the dry, geographically undisrupted area in which the fossil was found, thus making the discovery of N. hesitae even more noteworthy. 

Comparable to the size of a European starling, the structure of N. hesitae’s cranium reveals fascinating insights into its cognitive abilities and capacity to fly. One of the most surprising aspects of this discovery, however, is that the size of  N. hesitae’s cerebellum — the region of the brain which controls motor functions — is smaller than would be expected for a flying bird, puzzling researchers as to how it lifted its feet off the ground. Indeed, the family of birds to which  N. hesitae belongs — early birds — are thought to have managed by bounding and flap-gliding. These behaviours are still exhibited by modern-day birds, especially European starlings — the very bird to which N. hesitae is currently compared. The discovery of N. hesitae becomes that much more interesting when we consider that very few groups of organisms have ever learned to fly — bats, birds, and extinct pterosaurs (the first dinosaurs to develop flight), to name a few. These species do not share any evolutionary proximity which might enable knowledge of how they developed flight, making N. hesitae that much more crucial a link in understanding avian flight. 

Indeed, modern birds such as corvids and parrots are amongst the most intelligent species on the planet. Corvids demonstrate remarkable abilities in tool use, facial recognition, solving puzzles, and maintaining long-term relationships and family connections. The discovery of N. hesitae represents a remarkable opportunity to connect this intelligence of modern-day birds to their dinosaur ancestors, expanding our understanding of how the modern world developed. Although this is clearly a milestone moment for the field, future research may explore how N. hesitae interacted with its natural environment, encompassing predator-prey relationships, habitat features, and social behaviours. Regardless, these findings will encourage us to reconsider birds, and their intelligence, from a different perspective, and maybe — just maybe — forgive them a little for any incidents of food thievery!

Photo by Wikipedia Commons