Reproductive parameters, kidney fat index, and grazing activity relationships between the sexes in Cantabrian chamois Rupicapra pyrenaica parva

Reproductive parameters, kidney fat index and grazing activity of both sexes of Cantabrian chamois Rupicapra pyrenaica parva (Cabrera, 1910) in relation to age, season and year are presented and compared with those of other chamois subspecies and cervids. Females younger than three years old had not ovulated. Ovulated ovaries were significantly heavier than non-ovulated ovaries in March-April, and these differences remained until the following rutting season. All pregnant females carried a single foetus. A significant decrease in the percentage of parous females was found in 3-11 years age class (94%) compared with > 11 years (50%). There were no differences in the kidney fat index (KFI) between age classes for either of the sexes throughout the study period. Females showed a significant higher KFI in August-October 1993 than in August-October 1992, coinciding with a significantly greater abundance of grass in 1993. Throughout the year KFI in females showed less fluctuations than in males. Males began the rutting season with a significant KFI three times higher than did females. However, by the spring, the KFI of the males had fallen to half of that of the females. In March-April pregnant females showed a significantly higher KFI than non-pregnant or late-conception adult females. Feeding activity of females and sward height throughout the year were inversely related. Females grazed more actively than males in the summer, rut and spring, except in winter where no differences in feeding activity between sexes were found. The differences in the KFI and feeding activity are discussed in relation to the parental investment and the sexual dimorphism-body size theory.