How climbing influences parrot neck evolution

Parrots are an enigmatic group of animals that have captivated us with their array of colourful plumage and propensity for mimicry. However, fascinating features of parrots are not just skin deep and morphologists have long known that parrots possess a suite of interesting morphologies: from a pronounced hinge joint between the 'beak' and the top of the skull, to zygodactyl feet (two toes facing forward and two back) that are dextrous enough to manipulate food objects and makeshift tools.

Recent work has highlighted another amazing feature of parrots: they climb trees using their head, neck and hindlimbs! The forelimb of birds are heavily adapted for flight so that they are unable to bear weight and therefore cannot participate in climbing. In order to climb, parrots must utilise the head and neck instead of the forelimbs during vertical climbing, making it one of the only animals to use 3 'limbs' during locomotion. Whilst recent work has provided the scientific community with the underlying kinematics of this movement in parrots, we don't currently understand if climbing has any associated morphological adaptations of the neck vertebrae, nor how it has influenced parrot neck evolution.

My amazing MRes student (Anna Stuart) and I teamed up with Prof. Michael Granatosky to document how parrots climb across a broad selection of modern parrot species. We then used this data in conjuction with 3D geometric morphometrics and phylogenetic comparative methods to explore the statistical relationship between neck vertebral shape and climbing behaviours. We also investigated if this behaviour has led to convergence in the neck morphology of species of parrots that climb regularly.

This work is close to completion, and we expect to upload a preprint version to bioRxiv very shortly, watch this space!