The reproductive state of female roe deer (Capreolus capreolus) (n = 140) caught during 4 consecutive winters (January and February) was determined from progesterone concentrations in blood samples. We found that (i) females older than 20 months were pregnant almost every year, indicating that though monoestrous, this species can achieve a very high conception rate (98%); (ii) a significant proportion of females 20 months of age (corresponding to the usual age at first pregnancy) had not reached sexual maturity; and (iii) body weight measured in winter could be used to predict the probability of pregnancy for young females (20 months of age) but not for older females. The correlation observed between age, body weight, and reproductive success suggests the hypothesis that the proportion of young females that breeds is density dependent. Ecological conditions mediated by social behaviour and prevailing during the spring of birth could constitute the ultimate factor determining pregnancy rate at 20 months.
Patterns of growth and seasonal variation in body mass, kidney fat level, and bone marrow fat level were investigated in a roe deer population south of Paris. Size dimorphism was not apparent until the deer were 2 years of age, following a second period of rapid growth in males during spring-summer. No differences between the sexes in fat accumulation or in the periodicity of the annual fat cycle were observed. However, annual cycles of adult body mass were asynchronous between the sexes. Carcase mass was stable for much of the year, but one marked seasonal decline was observed in animals of each sex. For females (April -August) this reflected investment in late gestation and lactation, but among males (April-November) it was presumably linked to the costs of rutting. Contrary to reports for other ungulates, no over-winter decline in adult carcase mass, kidney fat level, or bone marrow fat level was observed, possibly because winters were mild. All four fat indices (kidney fat index, three bone-marrow fat indices) declined over spring -summer. This seasonal cyclicity does not match the energy requirements of reproductive activity, suggesting that the fat cycle is intrinsic, linked to seasonal metabolic variation in roe deer. We suggest that carcase mass is a more reliable index of condition in roe deer.RCsurnC : La croissance et les variations saisonnikres de la masse corporelles, de la graisse perirenale et de la graisse de la moelle osseuse ont ete etudies chez une population de Chevreuils. Le dimorphisme quant B taille n'apparait qu'B l'ige de 2 ans, B la suite d'une seconde periode de croissance rapide chez les miles au printemps et en ete. L'accumulation des graisses et la periodicite de leur cycle annuel ne diffkrent pas chez les miles et les femelles. Cependant les cycles annuels de la masse corporelle des adultes ne sont pas synchronises entre les deux sexes. La masse de la carcasse est relativement constante, mais une chute saisonnibe marquee se produit chez les deux sexes. Chez les femelles (avril-aoQt), elle correspond B l'investissement energetique important au moment de la gestation et de la lactation. Chez les miles (avril-novembre), elle est sans doute attribuable aux depenses energetiques liees au rut. Aucune diminution de la masse de la carcasse, de la graisse perirenale ou de la graisse de la moelle osseuse n'a ete observee chez les adultes au cours de l'hiver; ce resultat atypique peut Ctre dQ aux hivers doux. De plus, les quatre indices des graisses ont diminuk entre le printemps et 1'Cte. Cette cyclicite saisonnikre suggkre une origine intrinskque au cycle annuel des graisses, lie aux variations saisonnikres du metabolisme chez l'espkce. Nous recommandons l'utilisation de la masse de la carcasse comme indicateur de la condition physique chez le Chevreuil.
Indirect calorimetry measurements were made continuously over a 2-year period in 10 adult female roe deer (Capreolus capreolus) maintained in outdoor enclosures on ad libitum feeding. Results from adult nonpregnant does revealed no endogenous seasonal rhythm in resting metabolic rate (RMR), in contrast to most cervid species. Throughout the 2 years of our study, RMR (overall mean 4695 ± 65 kJ∙d−1) fluctuated in parallel with variations in body mass. The mass-specific RMR ranged from 221.2 ± 4.8 to 230.7 ± 4.0 kJ∙kg−1∙d−1 (466.0 ± 10.8 to 495.5 ± 9.7 kJ∙kg−0.75∙d−1). Results from pregnant females (five in the first year, four in the second) showed that their energy expenditure increased by 15% during the last 2 months of gestation, in step with the increase in body mass. A 27% increase in RMR was recorded in lactating females during the first month post partum. These results show that in a small-bodied cervid such as the roe deer, reproduction costs are no higher than in other wild herbivores.
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