4 April 2012 Morphology of primary feathers in two falcon species
Author Affiliations +
Primary feathers allow birds to fly; however, morphology and material properties of theses feathers vary in different bird species. We therefore analysed both morphology and material properties of primary feathers in two raptor species, the peregrine falcon (Falco peregrinus) which is the fastest vertical flyer known, and the kestrel (Falco tinnunculus), using scanning electron microscopy (SEM) and nanoindentation. The program AutoCAD was used for the computation of the moments of inertia. The reduced E-modulus of the cortex of the rachis of the first, fifth, and tenth primary were measured at proximal (10% of total rachis length), central (50%) and distal (75%) cross-sections. In all cross sections the kestrel showed higher E-moduli than the peregrine falcon (values varied between 6.7 and 9.1 GPa). In the primaries, values increased from proximal to central but decreased distally. Looking at the hardness, the kestrel had higher values than the peregrine falcon yet again. The main differences occurred in the first primary. Values ranged between 0.17 and 0.4 GPa. SEM studies revealed that the tenth primary was more stable in the peregrine falcon, featuring more hamuli than the kestrel at all analysed positions and longer hamuli at the distal positions. The higher moments of inertia found in the peregrine falcon caused a much higher bending stiffness in this species. Values were 4.4 to 9.1 times larger in the peregrine falcon than in the kestrel. Because the given structures are responsible for the stability of the feather face it seems that the feathers of F. peregrinus are more robust than those of F. tinnunculus. Even when considering the higher body mass of the peregrine falcon compared to the kestrel (3.4 times), the determined stability of the feather compensates for this problem.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
B. Honisch, H. Bleckmann, H. Schmitz, A. Schmitz, "Morphology of primary feathers in two falcon species", Proc. SPIE 8339, Bioinspiration, Biomimetics, and Bioreplication 2012, 833915 (4 April 2012); doi: 10.1117/12.917427; https://doi.org/10.1117/12.917427

Scanning electron microscopy



Atomic force microscopy


Current controlled current source

Electron microscopes

Back to Top