Ontogeny of aerial righting and wing flapping in juvenile birds

TL;DR

This study investigates how juvenile Chukar Partridge develop aerial righting skills from asymmetric wing movements to symmetric flapping, revealing insights into the early stages of bird flight evolution.

Contribution

It demonstrates that asymmetric wing movements for aerial righting precede symmetric flapping and wing assisted incline running in juvenile birds, informing theories of flight origins.

Findings

Aerial righting via body roll starts at 1 dph

Transition to symmetric flapping occurs after 8 dph

Vertical force production increases during descent

Abstract

Mechanisms of aerial righting in juvenile Chukar Partridge (Alectoris chukar) were studied from hatching through 14 days post hatching (dph). Asymmetric movements of the wings were used from 1 to 8 dph to effect progressively more successful righting behaviour via body roll. Following 8 dph, wing motions transitioned to bilaterally symmetric flapping that yielded aerial righting via nose down pitch, along with substantial increases in vertical force production during descent. Ontogenetically, the use of such wing motions to effect aerial righting precedes both symmetric flapping and a previously documented behaviour in chukar (i.e., wing assisted incline running) hypothesized to be relevant to incipient flight evolution in birds. These findings highlight the importance of asymmetric wing activation and controlled aerial manoeuvres during bird development, and are potentially relevant to understanding the origins of avian flight.