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The aim of this study was to describe the pattern and rates of growth of roe deer fawns up to the age of weaning. Eighteen fawns of Capreolus capreolus (Linnaeus, 1758) raised by their mothers in enclosures grew at decelerating rates after birth, with a monomolecular rather than sigmoid pattern. Bottle rearing modified profoundly the natural pattern of growth, but these fawns caught up with mother-reared fawns by weaning (about six months). There was no evidence for differential investment by the mothers in male and female offspring. Most mother-reared fawns showed an initial, near-linear phase in their first month (10/12 individuals). During this period milk provides all, or nearly all the nutrients; the rates of growth were high (145 g/day), and close to the value observed in a highly productive wild population. The decelerating rate of growth may be a consequence of allocation of resources to movement as these "hider" young become more active; and the monomolecular pattern may be commoner among ungulates than is currently realised.
The function of male territoriality in roe deer has been debated for decades. There now seems to be consensus that it is a mating tactic. As such, it is highly untypical though. The reasons being, first, males neither conform to the typical ‘resource defence’ territoriality model nor to the ‘mate defence’ territoriality model; second, territory defence commences several months in advance of the breeding season; and third, the territorial system seems to be very rigid, as practically all studies that have described the social organisation of the species have reported adult males to be territorial. In spite of the general agreement that territoriality is a mating tactic, conclusive evidence on which selective forces are responsible for the prevalent pattern is still lacking. In the present paper, it is suggested that territorial defence serves as a sexual ornament, i.e. ‘cleanness’ of other males on the territory, in combination with size of the ‘clean’ area, and tenure length are parameters used by females to estimate male phenotypic quality. The hypothesis generates at least four predictions, and available data provide support. It is concluded that although a firm test of the hypothesis remains to be undertaken, existing data support this, just as well as any other, explanatory model and therefore it should be taken into consideration.
We present data on fidelity to territory, and length of tenure (multi-year) for bucks of European roe deer Capreolus capreolus (Linnaeus, 1758) based on 26 radio-collared individuals that were followed for up to 5 years. Individual bucks showed a high degree of fidelity to summer territory, with consecutive year's activity centres being less than 200 m apart on average. An average 70% of one year's territory was within the borders of the previous year's territory. No buck occupied a territory which did not overlap with the previous year's territory. Activity centres of consecutive winter home ranges were on average 502 m apart, although this difference was not sig­nificant. Several cases of switching between non-overlapping winter ranges between years were observed. Annual survival was high (97%) and we observed only a single case of an old buck losing dominance on his former territory after a very hard winter. All other surviving bucks regained their dominance on their territories. It is suggested that the roe deer bucks were demonstrating an "always stay" strategy in order to gain the benefits of site familiarity. This is in keeping with the concept of roe deer territoriality being a relatively "low-risk low-gain" strategy where emphasis is placed on survival and multi-year tenure of a territory.
Knowledge about the mechanisms of embryonic diapause in European roe deer Capreolus capreolus (Linnaeus, 1758), although first described 140 years ago, is not extensive. In contrast to post mortem publications, this is an in-vivo study which monitored individual ovarian and uterine dynamics during diapause by transrectal ultrasonography. Ten roe deer were examined at 4 to 6-week intervals starting from the end of the breeding season (August) until after implantation (January), Sonographic appearance of corpora lutea and their average number observed per animal did not differ between pregnant (3.6) and non-pregnant (3.2) does prior to implantation. However, in pregnant animals (n = 5) endometrial changes associated with embryonic diapause were identified. The endometrium in pregnant does were low in echogenicity compared to the non-pregnant. Changes in echogenicity of the endometrium were first detected three months before implantation. Observed endometrial changes were quantified by computer-assisted grey scale analysis. Mean medians of grey scale histograms were lower in pregnant compared to non-pregnant animals beginning as from October. In late December and January, embryonic structures were detected in animals in which a low echogenic endometrium had been observed earlier. Ultrasono­graphy and grey scale analysis characterised efficiently the dynamic processes in the uterus and ovary during embryonic diapause in pregnant and non-pregnant roe deer.
In female roe deer Capreolus capreolus (Linnaeus, 1758), like in several deer species, first reproduction occurs before they have reached their full body size. This study quantifies, in young females, the energetic costs induced by the contemporaneously occurring events: growth and first reproduction. Resting metabolic rate and body mass were measured in young primiparous females from first mating to 4 months after parturition, and compared to values measured in fully-grown adult multiparous females. Throughout the 10-month period from mating to fawning, body mass increased in yearlings. Prior to the blastocyst implantation (month -5 before parturition) young females were lighter than adult females whereas after parturition they had the same body mass. Our results suggest that body growth was reinitiated during pregnancy in primiparous females. From mating to fawning, except in the first part of pregnancy, mass-specific metabolism was higher in primiparous females than in multiparous individuals indicating the occurrence of an additional cost due to growth in young females. The depressed level observed at the beginning of gestation could allow the resumption of growth at lower cost. Thus, the allocation of resources to both reproduction and growth was not detrimental to first reproduction in young female roe deer under experimental conditions with ad. lib feeding.
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