Year of Award

2026

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Ecology and Evolution

Department or School/College

Division of Biological and Biomedical Sciences

Committee Chair

Bret W. Tobalske

Commitee Members

Douglas Emlen, Zachary Cheviron, Matthew Bundle, Sharon Swartz, Eric Snively

Keywords

Aerodynamics, Biomechanics, Gusts, Perturbations, Ringneck Doves, Turbulence

Abstract

The aerosphere is a highly dynamic environment where turbulence (irregular, chaotic changes in airflow velocity) and unsteady airflows (variations in flow velocity with time at a given spatial point, e.g. gusts) are ubiquitous [1,2]. These airflows are known to perturb man-made aircraft [3,4], and are thus expected to challenge biological fliers such as birds. However, birds display remarkable flight control in turbulent and gusty conditions, suggesting that they have evolved mechanisms to resist aerial perturbations. This in-flight stability is broadly attributed to wing morphing, the capacity for wing shape and orientation to be altered during flight, yet how morphable wings improve flight stability in gusty conditions is not fully understood [5-9]. Moreover, the ecological impacts of turbulence on bird flight in the wild, and whether turbulence could have thus driven the evolution of perturbation-resisting mechanisms, are largely unknown [10].

In my dissertation I investigate both a) mechanisms promoting flight control in unsteady airflows and b) the costs of flight in environmental turbulence in ringneck doves (Streptopelia risoria). Chapters 1 and 2 test different wing morphing mechanisms employed by gliding doves to reject vertical gusts, which are particularly destabilizing perturbations for aircraft [4]. I describe two anatomical wing morphing mechanisms – feather aeroelasticity [11] and muscular preflexes [12] – which passively contribute to glide stability without modulation of neural input. I also demonstrate reflexive adjustments to wing kinematics following vertical gusts [12], and show that flight feathers likely facilitate reflexive responses by instantaneously sensing aerial perturbations [11]. Finally, in chapter 3 I test the impacts of environmental turbulence on bird flight outside of the lab. I provide direct evidence that atmospheric turbulence increases the metabolic power requirements of avian flight, supporting the hypothesis that aerial perturbations have driven the evolution of passive stability mechanisms [7]. Broadly, my dissertation improves our understanding of mechanisms which facilitate flight control in unsteady airflows in gliding birds, as well as the costs of avian flight in turbulent environments.

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© Copyright 2026 Rémy Alexandre Delplanche