Diet and internal anatomy of male Sharp-tailed Grous, Tympanuchus phasianellus, as related to age and position on the Lek

Abstract

Heart weight, gizzard weight, and caeca length of male Sharp-tailed Grouse (Tympanuchus phasianellus) that occupied central territories on four leks near Fort Albany, Ontario, were significantly but not disproportionately larger compared to peripheral individuals (and yearlings). Thus, relative heart size did not explain higher levels of activity maintained by central males and adults on the lek. No advantage in digestive efficiency between the classes studied was found using digestive morphology as the criterion. Further, no differences were found between age and lek location in type and energy content of diet. Perhaps differences in body condition between the classes, as has been shown previously, can be related to differences in gastro-intestinal microflora.