Fighting behaviour in territorial male roe deer <Emphasis Type=Italic>Capreolus capreolus</Emphasis>: the effects of antler size and residence

In all areas where they have been studied, male roe deer are believed to have a territorial mating system, although few quantitative studies have been conducted and there remains considerable debate about the function of male roe deer territories. We observed 139 aggressive interactions between male roe deer in Storfosna Island (Norway) during one territorial season (March–August). We recognised seven rank levels of escalation according to the potential danger of the behaviour. On the basis of the number of escalation levels included in the interactions, the complexity of the fights was also scored. We recorded the presence of other individuals during the interaction, the age, the antler size, the territorial status and the residency status of the two contestants and tested how these variables affected escalation, complexity and outcome of the fights. Most of the interactions ended with low levels of escalation, and physical contact occurred only in fights between two territorial bucks. The escalation was also affected by the difference in antler size index (the bucks escalated more when the difference in antler size was smaller) and increased with an increasing number of female deer present during the interaction. The resident buck won in 81% of the fights. When it drew or lost, it was generally both inferior in age and antler size, and the duration and escalation of the interactions were higher. However, even when a fight was lost, no territory loss occurred. These results are consistent with the evolutionary game theory and the proposed low risk–low gain strategy of roe deer bucks.     

Use of space and habitat selection by roe deer Capreolus capreolus in a Mediterranean coastal area: how does woods landscape affect home range?

The home-range dynamics and habitat selection of nine roe deer were studied from March 1994 to August 1994 in the Maremma Natural Park along the Tyrrhenian coast of Italy. The habitat was highly fragmented, with open agricultural fields prevailing in the study area (57%); the climate was Mediterranean. Data on spatial behaviour were collected by radio-tracking techniques. Habitat selection and structure were investigated by compositional and landscape analysis, both within the study area and within the home ranges. Animals of our sample showed spatial-use patterns varying from stationary to roaming. Stationary individuals used small home ranges while roaming ones moved, especially during the reproductive period in July and August. The percentage and structure of woodlands influenced the size of home ranges and the behaviour of males: stationary males used large amounts of woodlands within their home ranges and showed a territorial behaviour whereas males that used a high percentage of fields showed wider home ranges even during the territorial period. Females seemed to be less influenced by the presence and patch-structure of woodland within their home range. Landscape structure and habitat composition seemed to be important factors influencing the spatial behaviour of this roe deer population.     

Parturition date for a given female is highly repeatable within five roe deer populations

Births are highly synchronized among females in many mammal populations in temperate areas. Although laying date for a given female is also repeatable within populations of birds, limited evidence suggests low repeatability of parturition date for individual females in mammals, and between-population variability in repeatability has never, to our knowledge, been assessed. We quantified the repeatability of parturition date for individual females in five populations of roe deer, which we found to vary between 0.54 and 0.93. Each year, some females gave birth consistently earlier in the year, whereas others gave birth consistently later. In addition, all females followed the same lifetime trajectory for parturition date, giving birth progressively earlier as they aged. Giving birth early should allow mothers to increase offspring survival, although few females managed to do so. The marked repeatability of parturition date in roe deer females is the highest ever reported for a mammal, suggesting low phenotypic plasticity in this trait.     

Minimal activity in both proliferation and apoptosis of interstitial cells indicates seasonally persisting Leydig cell population in roe deer

Seasonally regulated breeding is associated with significant changes in testis mass, structure and function. This includes the variation in size, structure and function of the Leydig cells. Recently, interstitial cells have been characterised as a numerically constant population in roe deer. However, no consistent data are available regarding changes in the number of Leydig cells, their differentiation or turnover in seasonally breeding mammals. This study has quantified the numbers of both proliferating and apoptotic cells in roe deer testis bimonthly during a complete annual cycle. Proliferation was detected by immunolocalisation of PCNA and Ki-67 in tissue sections, whereas apoptosis was localised by the TUNEL technique and an antibody to caspase-3. The labelled cells were counted by using a computer-aided image-analysing system. The number of proliferating spermatogenic cells per tubule cross section showed seasonal changes with a maximum in April (14.9±0.6) and a subsequent decline up to December (1.6±0.3). Percentages of positive cells per square millimetre of interstitial area were below 1% throughout the year. The average number of apoptotic cells per tubule cross section was low and varied only between 0.5 and 1.4 (caspase-3) or 0.1 and 2.1 (TUNEL). In the interstitial compartment, only a few apoptotic cells (0.7%) were found sporadically scattered within the intertubular region during all studied seasonal periods. The results suggest that a constant total number of interstitial cells arise from a conserved cell population of changing functional state rather than from a steady-state population with a definite turnover of cells during seasonal changes in testicular activity.The study was supported by a grant from the Deutsche Forschungsgemeinschaft (BL 319/6-2).     

Low genotyping error rates in non-invasively collected samples from roe deer of the Bavarian Forest National Park

Genetic wildlife monitoring is increasingly carried out on the basis of non-invasively collected samples, whereby the most commonly used DNA sources are skin appendages (hairs, feathers) and faeces. In order to guide decisions regarding future adequate ways to monitor the roe deer (Capreolus capreolus) population of the Bavarian Forest National Park in Germany, we tested these two different types of DNA source materials to compare their suitability for genetic monitoring. We determined the haplotypes (d-loop) of 19 roe deer and genotyped each individual (tissue, hairs, faeces) across 12 microsatellite loci. The amount of missing and erroneous microsatellite alleles obtained from hair and faeces samples, respectively, was estimated based on comparisons with the corresponding tissue sample control. We observed no missing alleles in hair samples, but in fecal samples PCR failed in 30 out of 228 instances (19 individuals x 12 loci), corresponding to a frequency of missing alleles of 13.2% across all loci and individuals. In genotypes generated from hairs erroneous alleles were detected in 2 out of 228 instances (0.9%), while genotypes retrieved from fecal samples displayed erroneous alleles in 6 out of 198 remaining instances (3%). We conclude that both hair and fecal samples are generally well suited for genetic roe deer monitoring, but that fecal sample based analyses require a larger sample size to account for higher PCR failure rates.     

Apoptosis is not the cause of seasonal testicular involution in roe deer

Apoptosis is involved in the regulation of spermatogenesis. The involution of testes in seasonal breeders might be expected to involve enhanced apoptotic cell elimination. We have compared seasonally changing testicular apoptosis in roe deer with that in non-seasonally breeding cattle. Apoptotic cells were detected as TUNEL-positive cells by both flow-cytometric analysis and in situ localisation of fragmented DNA in tissue sections. Apoptosis-induced DNA fragments were also assessed by enzyme-linked immunosorbent assay (ELISA) in homogenised testicular parenchyma. As expected, the testis mass and the percentage of haploid cells in roe deer showed a seasonal pattern with a significant maximum during the rut (August), whereas no annual variation of these parameters was found in bulls. All three methods for determining apoptosis showed similar findings. Roe deer exhibited significant seasonal fluctuation of total apoptotic activity (ELISA, apoptotic cells per tubule cross section) with a maximum during the breeding season. However, the seasonal differences in the number of apoptotic cells corresponded to the variable total numbers of spermatogonia and spermatocytes per tubule cross section. Thus, the percentages of TUNEL-positive cells related to the combined number of both germ cell types showed no seasonal variance, as confirmed by percentages of apoptotic cells analysed flow-cytometrically. The maximum level of apoptosis during the rut in roe deer was similar to the values obtained during the invariably high spermatogenic activity in cattle. These results suggest that, in roe deer, apoptosis is not the cause of the seasonal involution of testes. This study was partially supported by grant Bl 319/6-1 from the Deutsche Forschungsgemeinschaft.     

Detection of Bartonella DNA in roe deer (Capreolus capreolus) and in ticks removed from deer

The potential role of roe deer as a sylvatic reservoir of Bartonella in north-west Poland has been assessed. In addition, ticks infesting roe deer were screened to assess their role as a vector and reservoir of Bartonella. Blood and tissue samples of 72 animals from north-western Poland were PCR-screened. Bartonella DNA was detected by using primers complementary to the intergenic spacer between the 16S and 23S rRNA genes, which is used for identification of over a dozen species of this genus. Products of three different sizes were detected: 230 and 290 bp, representative of two strains of Bartonella capreoli, and 190 bp, identified as Bartonella bovis. All the three amplicons were detected in the blood, spleen and liver from the roe deer. All samples from the heart, lungs and kidneys were PCR negative. In ticks (Ixodes ricinus), only the 290 bp fragment from B. capreoli was present. Generally, Bartonella infection rate in Capreolus capreolus amounted to 27.6% of the roe deer, but it was much higher during winter (62%) than in spring (6.9%). The results show that the roe deer may be a reservoir for B. capreoli and B. bovis. The infection detected in I. ricinus ticks (7.7%) suggests that ticks may act as a Bartonella reservoir and vector.     

Maternal and individual effects in selection of bed sites and their consequences for fawn survival at different spatial scales

We examined the relationship between survival of roe deer (Capreolus capreolus) fawns at Trois Fontaines, Champagne-Ardennes, France, and factors related to bed-site selection (predator avoidance and thermoregulation) and maternal food resources (forage availability in the maternal home range). Previous studies have demonstrated that at small scales, the young of large herbivores select bed sites independently from their mothers, although this selection takes place within the limits of their mother’s home range. Fawn survival was influenced largely by the availability of good bed sites within the maternal home range, not by the fawn’s selection of bed sites; however, selection for thermal cover when selecting bed sites positively influenced survival of young fawns. Typical features of a good home range included close proximity to habitat edges, which is related to forage accessibility for roe deer. The availability of bed sites changed as fawns aged, probably due to an increased mobility of the fawn or a different use of the home range by the mother; sites offering high concealment and thermal protection became less available in favor of areas with higher forage accessibility. Despite the minor influence of bed-site selection on survival, roe deer fawns strongly selected their bed sites according to several environmental factors linked to predator avoidance and thermoregulation. Fawns selected for sites providing concealment, light penetration, and avoided signs of wild boar (Sus scrofa) activity. Avoidance of sites with high light penetration by young fawns positively affected their survival, confirming a negative effect on thermoregulation due to reduced thermal cover. Selection for light penetration by older fawns was less clear. We discuss these results in the context of cross-generational effects in habitat selection across multiple scales, and the potential influence of the ‘ghost of predation past’.     

Diet of Eurasian lynx, Lynx lynx, in the boreal forest of southeastern Norway: the relative importance of livestock and hares at low roe deer density

The year-round food habits of lynx were studied using radio-telemetry and snow-tracking in the boreal forest of southeastern Norway. The main objectives of the study were to clarify the importance of domestic sheep and small prey species in the diet of lynx in an area with a very low density of roe deer. During the period 1995–1999, we found 193 scats and 358 kills made by lynx. Our results indicate that roe deer were the most common prey species (contributing to 83 and 34% of the biomass consumed in winter and summer, respectively), although a wide range of other species were also found, including mountain hares, tetranoids, red foxes, domestic sheep, wild reindeer, and even moose. Most of the diet was obtained by predation, although we did document several cases of scavenging. Roe deer were more important in the diet in winter than in summer, perhaps because they were easier to locate in winter as they clustered around feeding sites. In summer, domestic sheep and small prey increased in importance. Despite the very low density of roe deer in this study area, lynx seemed to still specialise on them, although domestic sheep did constitute a significant amount to their diet, especially for males and yearlings. However, the contribution of sheep to summer diet was far from that expected if their relative density was considered.     

The use of antlers to monitor temporal variation in environmental lead levels: a case study from an industrialized area in Germany

In order to assess temporal changes in ambient lead levels, Pb concentrations were determined in roe deer (Capreolus capreolus) antlers (n=116) that had been collected in the industrialized area of Siegen (western Germany) in the period 1948–2000. Lead concentrations ranged between 0.3 and 166.3 mg/kg dry weight. An overall decline in antler Pb concentration occurred from the mid-1970s onward, and lead concentrations in the samples from the periods 1980–1989 and 1990–2000 were significantly lower than those in samples from previous periods. Our findings indicate a marked decline in lead exposure of the roe deer inhabiting the study area in the recent past. This decline is attributed to a decrease in atmospheric lead deposition, caused mainly by the phase-out of leaded gasoline, and, in addition, by a reduction of lead emissions from stationary sources. The results of the present study and of previous investigations demonstrate that analysis of antler samples obtained in an area over a certain period can be used to reconstruct temporal changes in environmental lead levels.     

Predation processes: behavioural interactions between red fox and roe deer during the fawning season

Predation by red fox (Vulpes vulpes) is the most important mortality cause for neonatal roe deer (Capreolus capreolus) in Scandinavia. With the objective of investigating how the fox finds fawns and how antipredatory behaviour of roe deer females influences choice of hunting method, I analysed observations of interactions between red fox and roe deer females. The observations were collected over 14 years in a mixed forest/agricultural landscape in Sweden. Of 49 fox–doe encounters, the doe attacked the fox in 59%. In 90% of these attacks the fox was successfully deterred. In two observations a doe saved a fawn attacked by a fox. Two hunting methods used by the fox were discerned. In 28 cases foxes searched the ground, and in 18 cases they surveyed open areas, often from a forest edge. The latter behaviour seemed more directed at fawns and was seen leading to a capture attempt. Searching seemed less efficient and also difficult to conduct due to the aggressiveness of does. A surveying sit-and-wait type of hunting method thus appeared as the most successful. The possibility to use this method could explain why roe deer fawns are more vulnerable to fox predation in open habitats.     

Identification of Mycobacterium avium subsp. paratuberculosis in wild cervids ( Cervus elaphus hippelaphus and Capreolus capreolus ) from Northwestern Italy

Seventy-seven red deer (Cervus elaphus hippelaphus), 40 roe deer (Capreolus capreolus) from the Northwestern (NW) Alps (Turin Province, NW Italy) and 29 roe deer from the NW Apennines (Alessandria province, NW Italy) were examined for the presence of Mycobacterium avium subsp. paratuberculosis (MAP) by culture, IS900 nested polymerase chain reaction (PCR) and IS1311 PCR restriction endonuclease analysis for strain characterisation. MAP identification (nested PCR and/or culture) allowed us to detect 32.9% MAP-infected red deer and 22.5% infected roe deer in the NW Alps and 41.4% MAP infected roe deer in the NW Apennines. On the basis of the polymorphism present in the IS1311 sequence, all MAP isolates were characterised as cattle strains. Our results show that MAP circulates widely among populations of wild cervids in NW Italy.     

Influence of a deer carcass on Coleopteran diversity in a Scandinavian boreal forest: a preliminary study

We tested the effect of a large ungulate carcass on boreal forest biodiversity by contrasting the local abundance and diversity of Coleoptera around a roe deer Capreolus capreolus carcass and in a control plot, between 8 August and 3 September 2003, in southern Norway. The two plots differed both in occurrence and richness of species, which were almost double at the carcass plot, although the diversity indices were similar. The higher evenness of the control plot compensated for its lower number of species, probably because the carcass plot was a disturbed area, colonized by many species, which were represented by few individuals. The number of beetles captured each day correlated positively with temperature at the control plot, but not at the carcass plot, indicating that the presence of an abundant and concentrated resource increased the local activity of Coleoptera. The carcass is likely to create a particular microclimate, which could partly buffer against extremes of air-temperature variation. These preliminary results indicate that ungulate carcasses have a significant ecological impact, which should be further investigated to improve the management and restoration of European boreal forest ecosystems.