Raptor talon shape and biomechanical performance determines prey size

Credit: RS2Photography
Credit: Shyamal

Birds of prey, also known as raptors, rely heavily on their talons for capturing prey. Raptors include vultures, buzzards, kites and hawks and range dramatically in body size.

In this study we investigate whether raptor talon morphology has evolved primarily in response to different dietary demands, or if is largely constrained phylogeny or adult body mass. We compared the hallux talon of 21 species varying in body mass and feeding ecology, ranging from active predation on relatively large prey to obligate scavenging.

To quantify the variation in talon shape and biomechanical performance within a phylogenetic framework, we combined three dimensional (3D) geometric morphometrics, finite element modelling and phylogenetic comparative methods.

Raptors specialising in medium to large prey cluster at negative PC1 values and have longer and more curved talons. Non-predators (vultures, Corvus and Eolophus) cluster at positive PC1 values and are characterized by a less curved, and, overall, shorter talon. Source: Marie Attard adapted from Tsang et al. 2019 Scientific Reports.

Our results indicate that relative prey size plays a key role in shaping the raptorial talon. We found that raptor talon evolution has been strongly influenced by relative prey size, but not allometry (body mass) and, that talon shape and mechanical performance are good indicators of feeding ecology.

Stress in raptor talons are highly correlated with relative prey size but not by allometry. Source: Marie Attard adapted from Tsang et al. 2019 Scientific Reports.

Publication

Tsang LR, Sansalone G, Wilson LAB, Attard MRG, Ledogar J and Wroe S (2019). Raptor talon shape and biomechanical performance are controlled by relative prey size but not by allometry. Scientific Reports. 9: 7076. DOI: 10.1038/s41598-019-43654-0

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