BRAIN VOLUME OF TAIGA MOOSE (ALCES ALCES SP.) IN RELATION TO SKULL PARAMETERS - A PILOT STUDY

Abstract

The ontogeny of the skull was studied by comparing brain case volume (BCV) and 13 cranial parameters of 30 male and 24 female moose of known age harvested in 1979. Results: (1) As with other cervid skulls, the males exhibited greater variability in brain growth than females; (2) Cohorts born in 1976 and 1977 had smaller BCV then those of 1978 and 1979; (3) The skull was fully developed by 40 months of age; (4) The height and width of the brain case related well with BCV; (5) A trend in sex dimorphism was evident, similar to that for the maximum upper orbital width; (6) Minimum frontal bone width was highly sex dimorphic, growing hyperbolically in males and linearly in females; (7) The eye angle enlarged during the first 3 years from 34° ± 6 to 44° ± 8. Four Alaskan male moose (older than 6 years of age) had eye angles of 30° to 38°, i.e. less than any taiga moose over 2 years old. This could mean that stereopsis in mature taiga moose is better developed than in its tundra relatives; (8) No significant sex dimorphism was found in the relationships between maximum upper orbital width and the parameters of maximum and condyle-basal lengths, and maximum width of the brain case. Good correlation exists for maximum length (ML) vs. pedicle diameter. It seems that BCV could be a valuable tool for prediction of generation performance and population status. Dentition patterns in calves and yearlings point to a 3 months calving period.