Comparative morphology of the glandular stomach and the gizzard of Large-billed and Carrion Crows

Abstract

Morphological and histological studies to analyse the characteristics of the glandular stomach and the gizzard of Large-billed Crows Corvus macrorhynchos and Carrion Crows C. corone were performed using light and electron microscopes, revealing several interspecific differences. The total area of the glandular stomach of C. macrorhynchos was larger than that of C. corone. Although there was no significant difference in the thickness of the glandular stomach wall between the two species, the glandular stomach gland layer in C. macrorhynchos was thicker than that of C. corone, whereas the muscle layer in C. corone was thicker than that of C. macrorhynchos. In addition C. corone had a thicker gizzard wall than that of C. macrorhynchos, and the muscle layer of the C. corone gizzard was proportionately much thicker than that of C. macrorhynchos. It has been reported that although both species are omnivores, C. macrorhynchos is slightly more carnivorous, whereas C. corone tends towards herbivory. Our results suggest that the interspecific differences in stomach histology and morphology might be the result of these dietary differences between C. macrorhynchos and C. corone.