Functional morphology of the forelimb musculature reflects flight and foraging styles in aquatic birds

Abstract Aquatic birds show a great diversity of locomotion styles and wing morphologies, from penguins that are fully specialized for an aquatic life to species aerial flyers also use their wings underwater propulsion (e.g. auks shearwaters). Moving between the air–water interface exerts conflicting pressures on body anatomy diving birds. In this work, we investigated functional morphology forelimb musculature 18 display variety flight foraging styles. Muscle architecture was related function, with special emphasis muscle mass. Dissections one forelimbs 20 specimens waterbirds were performed obtain numerical data architecture. Total mass scaled isometrically 1.0 , whereas fascicle length 0.284 which is consistent previous results scaling in raptors. A principal component analysis (PCA) normalised masses resulted biplot where three main morphological groups can be distinguished. Anatids (ducks geese) occupy space represented by muscles activated during downstroke. Auks clustered together region dominated assist elevation showed degree hypertrophy. The rest grouped lower limits both PCs facilitate flexion–extension stabilisation loaded. distribution seemed style non-significant influence shared phylogenetic history ( K mult: 0.71, p value: 0.083, 10,000 permutations).