LEG MORPHOLOGY AND FEEDING POSTURES IN 4 PARUS-SPECIES - AN EXPERIMENTAL ECOMORPHOLOGICAL APPROACH

The foraging behavior of four Parus species feeding at artificial feed ers was studied, while controlling for ecological variables related to patch characteristics (food quality, food access, and escape distance to the nearest refuge). Hindlimb morphology (osteology and myology) w as analyzed and compared with foraging postures at feeders. Using the Long-Tailed Tit as an appropriate outgroup for comparison, and conside ring functional changes associated with morphological changes, we demo nstrated the existence of clear ecomorphological patterns relating for aging postures and hindlimb morphology in the four Parus species studi ed. The Blue Tit uses hanging postures preferably and its hindlimb mor phology is modified for helping leg flexion. The Crested Tit more ofte n stands and its hindlimb morphology is modified to aid leg extension. Great and Coal Tits are ecologically and morphologically intermediate between the two former species. Our results show morphology as a dete rminant of locomotion mode. Since foraging postures are tightly associ ated with substrate use, then morphology should be considered when stu dying pressures determining community organization. Our proposed integ rative method for dealing with ecomorphology can be valuable in demons trating the adaptiveness of morphological structures in phylogenetical ly and ecologically related species.