The respiratory system influences flight mechanics in soaring birds

Schachner, Emma R, Moore, Andrew J, Martinez, Aracely, Diaz, Raul E Jr, Echols, M Scott, Atterholt, Jessie, Kissane, Roger WP ORCID: 0000-0001-9385-2584, Hedrick, Brandon P and Bates, Karl T ORCID: 0000-0002-0048-141X (2024) The respiratory system influences flight mechanics in soaring birds NATURE, 630 (8017). 671-+. ISSN 0028-0836, 1476-4687

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Abstract

The subpectoral diverticulum (SPD) is an extension of the respiratory system in birds that is located between the primary muscles responsible for flapping the wing^1,2. Here we survey the pulmonary apparatus in 68 avian species, and show that the SPD was present in virtually all of the soaring taxa investigated but absent in non-soarers. We find that this structure evolved independently with soaring flight at least seven times, which indicates that the diverticulum might have a functional and adaptive relationship with this flight style. Using the soaring hawks Buteo jamaicensis and Buteo swainsoni as models, we show that the SPD is not integral for ventilation, that an inflated SPD can increase the moment arm of cranial parts of the pectoralis, and that pectoralis muscle fascicles are significantly shorter in soaring hawks than in non-soaring birds. This coupling of an SPD-mediated increase in pectoralis leverage with force-specialized muscle architecture produces a pneumatic system that is adapted for the isometric contractile conditions expected in soaring flight. The discovery of a mechanical role for the respiratory system in avian locomotion underscores the functional complexity and heterogeneity of this organ system, and suggests that pulmonary diverticula are likely to have other undiscovered secondary functions. These data provide a mechanistic explanation for the repeated appearance of the SPD in soaring lineages and show that the respiratory system can be co-opted to provide biomechanical solutions to the challenges of flight and thereby influence the evolution of avian volancy.

Item Type:	Article
Uncontrolled Keywords:	Muscle, Skeletal, Respiratory System, Lung, Animals, Hawks, Respiration, Flight, Animal, Models, Biological, Female, Male, Biological Evolution, Biomechanical Phenomena, Wings, Animal
Divisions:	Faculty of Health & Life Sciences Faculty of Health & Life Sciences > Inst. Life Courses & Medical Sciences
Depositing User:	Symplectic Admin
Date Deposited:	30 Apr 2024 07:24
Last Modified:	22 May 2026 21:42
DOI:	10.1038/s41586-024-07485-y
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3180637
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