Inter‐relationships among body mass, jaw musculature and bite force in birds

• Published in: Journal of zoology (1987) Vol. 317; no. 2; pp. 129 - 137
• Main Authors: Deeming, D. C., Harrison, S. L., Sutton, G. P.
• Format: Journal Article
• Language: English
• Published: London Blackwell Publishing Ltd 01-06-2022
• Subjects: Allometry; Avian; Biomechanics; Birds; bite force; Biting; Body mass; Diet; Jaw; jaw musculature; Mass; Mathematical analysis; Mechanical properties; Morphology; Muscle contraction; Muscles; Phylogeny; physiological cross‐sectional areas; Species; Transducers; Vertebrates
• ISSN: 0952-8369; 1469-7998
• DOI: 10.1111/jzo.12966

Bite force can provide an insight into the feeding biomechanics and ecology of vertebrates. There has been an increasing interest in bite force in birds with data being collected using force transducers although bite forces have also been calculated from the mass of the jaw musculature. Studies have sought to find ecological correlates between bite force and diet or feeding style as well as with morphology. This study collated data reported in the literature for bite force and mass of the jaw musculature in birds and explored the relationships between these variables and their relationships with body mass to test two hypotheses. First, bite force and mass of the jaw musculature would scale with body mass irrespective of the phylogeny. Second, bite force and mass of the jaw musculature would be directly related to each other and be unrelated to phylogeny. Phylogenetically controlled analyses showed that in relation to body mass there were different relationships with bite force, and with the mass of the jaw musculature, for non‐passerine (isometry and negative allometry, respectively) and passerine species (both positive allometry). By contrast, a single significantly positively allometric relationship described the relationship between jaw muscle mass and bite force. These relationships were driven in part by the diet of the species concerned but also may reflect morphological differences in jaw musculature. The few studies that compare measured and calculated bite force for the same species show that values derived from muscles were higher. Detaching muscles from their points of origin and insertion to calculate physiological cross‐sectional area may be biasing bite force calculations.
Bite force of a variety of birds is compared against body mass and the mass of the jaw musculature with phylogenetically controlled analyses. The discussion places the results within a review of the key elements of the literature surrounding the determination and significance of bite force in birds.