Endocranial morphology of birds of prey and its correlation with their life strategies

DE MENDOZA RS; MOSTO, M.C.; DEGRANGE, F.J.

Conferencia; I Worldwide Raptor Conference; 2013

In order to find qualitative and quantitative features associated with different life strategies (e.g.,food habit, moment of activity, etc), 23 skulls of diverse predatory birds from the families Falconidae, Accipitridae, Pandionidae, Cathartidae, Tytonidae and Strigidae were scanned using tomographies and their endocasts were digitally generated. This 3D virtual structure reflects the volume and the external morphology of the brain due to the thinness of the bird’s meninges. Diurnal raptors are characterized by a heart-shaped telencephalon in dorsal view, cranially tapered and caudally straight or notched, with a great lateral expansion, specially in Geranoaetus and Harpyhaliaetus (Accipitridae); relatively small wulsts although craniocaudally enlarged, separated by a well-marked fissura interhemisferica in Pandion (Pandionidae); a relatively large cerebellum with developed auricula and reduced olfactory bulbs. Within diurnal raptors, the active predators show large tectum mesencephali, being the largest in Buteo,Accipiter and Falco and having a greater cranioventral development in Pandion. The scanvergers Neophron (Accipitridae) and Coragyps (Cathartidae) have a cranially flat telencephalon, strongly notched caudally and large olfactory bulbs. Both taxa share with the opportunists Milvago and Caracara (Falconidae) and with the nocturnal raptors (Strigiformes),the relatively small size of the tectum mesencephali and its slightly cranial position. The nocturnal raptors are characterized by a proportionally large telencephalon, a weakly extended dorsocaudally cerebellum and hypertrophied wulst, the later feature possibly associated with stereoscopy. The volume of the endocast shows an allometric relationship with the body mass in all cases. However the ratios of the wulst and tectum mesencephaly with respect to the telencephalon allow the distinction of diurnal raptors, scavengers + opportunists, and nocturnal birds of prey, as the qualitative features do.