Aims: The main aim of this study was to determine whether an ecomorphological pattern there exists relating muscular morphology and migratory behaviour in a group of passerines.
Methods: Analysis by dissection was made of the main forelimb muscles related to flight: muscle (m.) pectoralis, m. supracoracoideus, m. deltoideus major, m. triceps brachii and m. biceps brachii. The gross morphology of these muscles was studied in 10 pairs (genera) of species using a phylogenetically-based method of comparison. Estimation was also made of the force these muscles are able to develop upon contraction and their mass was taken. Within each pair (genus), one species was migrant and the other sedentary.
Results: Among species, none qualitative differences in muscles morphology were found. However, migrant species showed relatively stronger and heavier m. pectoralis than their sedentary counterpart, the rest of the muscles studied not differing either in their mass or in the force they develop upon contraction between these two groups of species.
Conclusions: M. pectoralis is the main wing depressor. Modifications found in migrant species increase the force this muscle is able to develop upon contraction, they being interpreted as adaptive modifications in migrant species leading to a more efficient forward flight which is that needed for migrating.
