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Fat content was not dependent on size (p = 0.1), sex (p = 0.4) or the interaction sex by period (p = 0.1) but changed with the period (F₃₍₇4 = 4.3, p < 0.01). It remained constant in the fali and midwinter and declined progressively to reach a level 25.8% lower in summer (Tukey: p < 0.01) (figurę 4.4f).

We found no significant period by sex interaction (p = 0.5) on water content but body water varied with size (Fi, ri= 13-8, p< 0.001), sex (Fi,72= 25.1, p< 0.0001) and period (F_3f72=3.3, p < 0.05). Controlling for size, the male’s body (5170 ± 70 mg) contained on average 6.3% morę water than that of females (4860 ± 70 mg). Water content increased by 8.4% between the fali and midwinter (Tukey: p < 0.01) and then decreased by 6.4% by the end of winter (Tukey: p < 0.05) to stay constant until summer (figurę 4.4g).

Figurę 4.4 Seasonal variation in organ groups throughout the year. Least square mean of A) size-independent digestive organ, B) cardiopulmonary organ, C) size-independent muscle, D) brain and E) size-independent skin lean dry masses as well as of F) fat and G) size-independent water content. Least square means were obtained from a GLM including period, sex, period*sex as independent variables (and size as covariate for digestive organs, muscles, skin and water content). Different letters represent significant difference between periods.