Tick burden on European roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>)

In our study we assessed the tick burden on roe deer (Capreolus capreolus L.) in relation to age, physical condition, sex, deer density and season. The main objective was to find predictive parameters for tick burden. In September 2007, May, July, and September 2008, and in May and July 2009 we collected ticks on 142 culled roe deer from nine forest departments in Southern Hesse, Germany. To correlate tick burden and deer density we estimated deer density using line transect sampling that accounts for different detectability in March 2008 and 2009, respectively. We collected more than 8,600 ticks from roe deer heads and necks, 92.6% of which were Ixodes spp., 7.4% Dermacentor spp. Among Ixodes, 3.3% were larvae, 50.5% nymphs, 34.8% females and 11.4% males, with significant seasonal deviation. Total tick infestation was high, with considerable individual variation (from 0 to 270 ticks/deer). Adult tick burden was positively correlated with roe deer body indices (body mass, age, hind foot length). Significantly more nymphs were found on deer from forest departments with high roe deer density indices, indicating a positive correlation with deer abundance. Overall, tick burden was highly variable. Seasonality and large scale spatial characteristics appeared to be the most important factors affecting tick burden on roe deer.     

Abundance estimation of <Emphasis Type="Italic">Ixodes</Emphasis> ticks (Acari: Ixodidae) on roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>)

Despite the importance of roe deer as a host for Ixodes ticks in central Europe, estimates of total tick burden on roe deer are not available to date. We aimed at providing (1) estimates of life stage and sex specific (larvae, nymphs, males and females, hereafter referred to as tick life stages) total Ixodes burden and (2) equations which can be used to predict the total life stage burden by counting the life stage on a selected body area. Within a period of 1½ years, we conducted whole body counts of ticks from 80 hunter-killed roe deer originating from a beech dominated forest area in central Germany. Averaged over the entire study period (winter 2007–summer 2009), the mean tick burden per roe deer was 64.5 (SE ± 10.6). Nymphs were the most numerous tick life stage per roe deer (23.9 ± 3.2), followed by females (21.4 ± 3.5), larvae (10.8 ± 4.2) and males (8.4 ± 1.5). The individual tick burden was highly aggregated (k = 0.46); levels of aggregation were highest in larvae (k = 0.08), followed by males (k = 0.40), females (k = 0.49) and nymphs (k = 0.71). To predict total life stage specific burdens based on counts on selected body parts, we provide linear equations. For estimating larvae abundance on the entire roe deer, counts can be restricted to the front legs. Tick counts restricted to the head are sufficient to estimate total nymph burden and counts on the neck are appropriate for estimating adult ticks (females and males). In order to estimate the combined tick burden, tick counts on the head can be used for extrapolation. The presented linear models are highly significant and explain 84.1, 77.3, 90.5, 91.3, and 65.3% (adjusted R ²) of the observed variance, respectively. Thus, these models offer a robust basis for rapid tick abundance assessment. This can be useful for studies aiming at estimating effects of abiotic and biotic factors on tick abundance, modelling tick population dynamics, modelling tick-borne pathogen transmission dynamics or assessing the efficacy of acaricides.     

The effect of environmental gradients on the bed site selection of roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>)

A wildlife species’ selection of bedding sites is often characterised by strong trade-offs, as habitat quality, predator avoidance and foraging needs should be achieved simultaneously. Human activities often represent major threats in addition. In areas of intensive agriculture, e.g. mowing is one of the main causes of mortality of roe deer (Capreolus capreolus) fawns due their hiding strategy. For a species’ offspring, the selection of bedding sites is particularly crucial and thus, identifying how and when animals use such habitats is important for management. We used a long-term dataset of marked roe deer fawns in Switzerland (1971–2015) to reveal the characteristics of optimal bedding sites within the first two weeks of a fawn’s life in three contrasting landscapes and the potential trade-offs that may occur. We hypothesised that roe deer adjust the selection of bedding sites to current environmental conditions and available habitat to achieve sufficient levels of predator avoidance and thermoregulation necessary for the fawn’s survival, as well as the availability of sufficient food resources for the mother doe. We found that, in general, grassland habitats with medium vegetation height (20–50 cm) and habitats in close proximity to the edge of the forest were favoured to achieve those basic requirements. However, the use of bed site habitats differed between the three contrasting landscapes in dependence of elevation and hence vegetation phenology. Our results provide essential information to reduce mortality rates caused by mowing and improve the reproductive success of this species.     

Effectiveness of odour repellents on red deer (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) and roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>): a field test

Chemical repellents are promoted as a method to reduce ungulate–vehicle collisions and ungulate browsing damages to agricultural and forestry resources. We tested the effectiveness of two odour repellents (Mota FL and Wolf Urine) on the foraging behaviour and area avoidance of free-ranging roe deer (Capreolus capreolus) and red deer (Cervus elaphus). The effects of the repellents were assessed by comparing deer visitation rates to sand arenas before and after application of repellents and visitation rates to control arenas. Neither of the tested products reduced deer visitation rates. Rapid habituation to olfactory stimuli and lack of sensitivity to predator odours may explain the ineffectiveness of the repellents to alter the behaviour of the deer. The results indicate that the tested products have no effects on roe deer and red deer behaviour and suggest that the effectiveness of the chemical area repellents as a measure to reduce deer–vehicle collision risk and browsing damages is questionable.     

Description and epidemiological implications of <Emphasis Type="Italic">S. scabiei</Emphasis> infection in roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) originating from chamois (<Emphasis Type="Italic">Rupicapra rupicapra</Emphasis>)

The authors describe a case of Sarcoptes scabiei transmission from a chamois (Rupicapra rupicapra) kid to three roe deer (Capreolus capreolus) fawns kept in captive cohabitation in a wildlife rehabilitation centre for approximately 4 months. Symptoms in the two male fawns started developing 1 week after skin lesions were noticed in the kid, whereas a delayed (75 days later) appearance of scabies signs was observed in the female fawn. A severe generalised form of scabies rapidly developed in a male fawn, but lesions in the other two healed after triple inoculation of ivermectin at 15 days intervals. These roe deer were monitored for specific anti-S. scabiei antibodies with an immunoblotting technique. The strongest antibody response was exhibited during the clinical phase of the infection and then rapidly declined post-treatment. Interestingly, the female fawn developed immunoglobulin G to S. scabiei proteins more than 2 months before the onset of clinical scabies. Since all captive roe deer appeared sensitive to infection with S. scabiei var. rupicaprae, the authors hypothesise that the sporadic frequency of spontaneous scabies in this Cervid host may be attributed to avoidance of direct contacts with moribund or recently dead scabietic chamois, and/or to a self-limiting (and therefore difficult to detect) course of the disease after infrequent infectious contacts and/or exposure to lower infectious doses than in the described episode.     

Calibration of remotely collected acceleration data with behavioral observations of roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis> L.)

Long-term, remote monitoring of animals under natural conditions is essential for obtaining information on animal activity. Advances in biotelemetry have led to the construction of low-power accelerometers placed on Global Positioning System (GPS) collars. Such acceleration data from roe deer have not yet been classified to the various behavioral categories. Here, we determined the threshold values of such data for different behavioral categories. We equipped captive roe deer with Global Positioning System–Global System for Mobile Communications/dual-axis acceleration sensor neck collars and simultaneously measured their movement and observed their behavior. The difference between feeding and slow locomotion was significant on the x- but not the y-axis, and both of these two behavioral categories differed significantly from resting and fast locomotion. Specific thresholds for the behavioral categories—resting, feeding, and slow and fast locomotion—were established by recursive partitioning. We compared the behavior determined by these threshold values with observed behavior and found that 92% of the behavioral categories were correctly assigned. A comparison of our results with those of earlier studies showed that thresholds derived for one species cannot be directly applied to another species. We provide recommendations for the further development of acceleration sensors based on the results obtained in this study.     

Survival rates and causes of mortality of roe deer <Emphasis Type="Italic">Capreolus capreolus</Emphasis> in a rural landscape,eastern Poland

Game species in the cultural landscapes of Europe are exposed to several sources of anthropogenic pressure. Whilst hunting is part of coordinated wildlife management, poaching is difficult to quantify, and hence, relatively little is known about its impact on survival patterns of game species. We estimated survival and cause-specific mortality rates of 31 roe deer Capreolus capreolus in the surroundings of the Bia?owie?a Primeval Forest, eastern Poland, from 2010 to 2013. The study area consisted of large, extensively used agricultural fields and a mosaic of pine plantations, which were interspersed with natural forest stands and small agricultural fields and meadows. Roe deer were regularly hunted and the forested part of the study area was traversed by large carnivores. Annual survival rate of all deer was 0.69 and did not differ between seasons. Annual survival rates of females and males in each age class (young and adult) were similar. Poaching was a major source of mortality (6 out of 13 roe deer deaths), and poachers did not prefer any sex or age. Adult survival (0.77) was higher than survival of young individuals (0.53); this trend was stronger when poaching was excluded from the analysis. All cases of poaching were recorded between mid-September and February. Although the two parts of the study area were exposed to a similar degree of anthropogenic pressure, all poached individuals occupied home ranges in the mosaic, where the forest cover in home ranges of roe deer was significantly higher than in the field.     

Demographic crash associated with high parasite load in an experimental roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) population

In March 2002, ten roe deer (Capreolus capreolus) were released in a partly wooded 14.2-ha enclosure to investigate the effect of high population density on vegetation cover and demographic parameters. However, in mid 2003, five animals died after rapid emaciation. Two other deer were killed to carry out further post-mortem examination. In addition to a general loss of body mass and injuries in males caused by the healthiest of them, we found a high level of parasitism. The remaining animals received anti-parasite treatment, and four other treated roe deer were added into the enclosure. All the deer were then captured and treated against parasites twice a year, the fawns being removed when first captured. Four years after the crash, the population seemed healthy: deaths no longer occurred; mean adult body mass reached 27.6 kg in March; females produced on average 1.6 fawns per year, with a mean body mass of 13.8 kg in October and 16.7 kg in March. Furthermore, undergrowth cover changed little since March 2004. These results suggest that outbursts of parasites may cause population crashes in high-density situations before the onset of nutritive stress and may explain certain cases of ‘abnormal’ (massive) mortality recorded in roe deer.     

<Emphasis Type="Italic">Trueperella pyogenes</Emphasis> isolated from a brain abscess of an adult roebuck (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>)

The present study was designed to characterize phenotypically and genotypically a Trueperella pyogenes strain isolated from a brain abscess of an adult roebuck (Capreolus capreolus). The species identity could be confirmed by phenotypical investigations, by MALDI-TOF MS analysis, and by sequencing the 16S ribosomal RNA (rRNA) gene, the 16S–23S rRNA intergenic spacer region (ISR); by sequencing the target genes rpoB, gap, and tuf; and by detection of T. pyogenes chaperonin-encoding gene cpn60 with a previously developed loop-mediated isothermal amplification (LAMP) assay. The T. pyogenes strain could additionally be characterized by PCR-mediated amplification of several known and putative virulence factor-encoding genes which revealed the presence of the genes plo encoding pyolysin and nanH and nanP encoding neuraminidases; the genes fimA, fimC, and fimE encoding the fimbrial subunits FimA, FimC, and FimE; and the gene cbpA encoding collagen-binding protein CbpA. The present data give a detailed characterization of a T. pyogenes strain isolated from a brain abscess of a roebuck. However, the route of infection of the roebuck remains unclear.     

The modular organization of roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) body during ontogeny: the effects of sex and habitat

Background

As a small artiodactyl, the roe deer (Capreolus capreolus L.) is characterized by biological plasticity and great adaptability demonstrated by their survival under a wide variety of environmental conditions. In order to depict patterns of phenotypic variation of roe deer body this study aims to quantify variation during ontogenetic development and determine how sex-specific reproductive investment and non-uniform habitat differences relate to phenotypic variation and do these differential investments mold the patterns of phenotypic variation through modular organisation.

Results

Patterns of phenotypic correlation among body traits change during the ontogeny of roe deer, with differential influence of sex and habitat type. Modularity was found to be a feature of closed habitats with trunk+forelimbs+hindlimbs as the best supported integration/modularity hypothesis for both sexes. The indices of integration and evolvability vary with habitat type, age and sex where increased integration is followed by decreased evolvability.

Conclusion

This is the first study that quantifies patterns of correlation in the roe deer body and finds pronounced changes in correlation structure during ontogeny affected by sex and habitat type. The correlation structure of the roe deer body is developmentally written over the course of ontogeny but we do not exclude the influence of function on ontogenetic changes. Modularity arises with the onset of reproduction (subadults not being modular) and is differentially expressed in males and females from different habitats. Both adult males and females show modularity in primordial, closed habitats. Overall, all these findings are important as they provide support to the idea that modularity can evolve at the population level and change fast within a species.

     

Spatial patterns and density dependence in the dynamics of a roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) population in central Italy

The demography of roe deer living in a mountain area of central Italy was studied from 1995 to 1999 with 104 radio-tagged animals, including fawns and adults of both sexes. From spring surveys we estimated population density by mark-resighting (average: 53.8dž.8 individuals km^-2) and found an average fawn/doe ratio of 0.75ǂ.4. The fawn/doe ratio was negatively correlated to density suggesting density-dependent regulation in this population. Using culled and net-trapped individuals we evaluated the dressed body weights of adult males (23.1ǃ.0 kg) and females (22.0ǃ.0 kg), which indicated a low level of sexual dimorphism. The potential litter size (1.44ǂ.1 embryos) depended on female body weight and a threshold of 20.9ǃ.4 kg separated adult females carrying one or two embryos. Both fawn (0.38ǂ.07) and adult survival (0.90ǂ.07) were evaluated from radiotagged individuals and no gender effect was observed in either age class. During the study period we recorded a population decline in one part of the study area and an increasing fawn mortality, which was attributed to the spreading of an enteropathogenic desease. The study revealed an unexpected spatial structure in population dynamics at a scale of few square kilometres. In the two studied subareas, which are very close and ecologically similar, we documented significant differences in several demographic parameters: females in the subarea with the highest deer density produced smaller litters and allocated their reproductive effort preferentially to males, which is consistent with the hypothesis that local resource competition determines sex allocation in roe deer. The importance of spatial variability with respect to roe deer demography was overlooked in previous studies and our results raise new interesting research questions relative to the study of population equilibria which are also relevant for the management of this important game species.     

Evaluation of the eye lens method for age determination in roe deer<Emphasis Type="Italic">Capreolus capreolus</Emphasis>

Eye lens weight curves were obtained from a sample of 522 male and 171 female free-living roe deerCapreolus capreolus (Linnaeus, 1758), collected during the regular annual harvest 1998/99–2005/06 (May–January) in 12 different field hunting grounds in Vojvodina (North part of Serbia). We found no significant differences in eye lens weight between males and females within the same age class (except age class 1). Thus, the eye lens weight data for both sexes within the same age class were pooled for further analyses. The rate of increase in eye lens weight declined at a relatively early age, but lenses continued to increase in weight through age class 9. However, there was a considerable overlap in ranges of eye lens weights within all age classes, which restricted the usefulness of this method. The estimate precision of the eye lens method in determining age was evaluated by the comparison of “known age” (cementum layer technique) and predicted age (eye lens weight technique). We examined model validity on 78 roe deer not used previously to construct the regression line. The lack of correspondence between the two techniques was evident among individuals within older age classes. The percentage of correctly determined age rapidly declined already from age class 4 (<30%).     

Impact of environmental diversity of hunting complexes in the Lublin region on ontogenetic quality indicators in roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>)

Populations of game are not confined to single ecosystems but function within higher-order units, e.g. ecological landscape. The basis for the establishment of the hunting complexes was the assumption that the existing game hunting grounds, i.e. the basic units implementing game management, are too small and do not cover the natural areas inhabited by game populations. Roe deer are flexible species and easily adapt to various site conditions, so they inhabit many different habitats, from large forest complexes, through small in-field tree stands and shrubs, to treeless grounds and field monocultures. The aim of the study was to determine a possible impact of environmental conditions prevailing in the hunting complexes of the Regional Directorate of State Forests (RDLP in Lublin) on the ontogenetic quality of roe deer. The study was conducted on 518 European roe deer (Capreolus capreolus) aged from 4 to 7 years (379 bucks and 139 does) harvested within hunting seasons 2010/2011–2013/2014. The results have shown that animals originating from areas with greater forest cover and denser stands are characterised by lower values of the mean ontogenetic quality parameters (carcase weight, kidney fat index, chest girth, weight of antlers) in comparison with animals from typical agricultural areas with fragmented forest complexes. These results indicate that, even in the case of such a eurytopic species as the roe deer, the ontogenetic quality differs between individual hunting complexes. The study has proved that strategies for hunting management of the roe deer should take into account the impact of the landscape structure, which provides a rationale behind creation of hunting complexes.     

Experimental evidence for density-dependence of home-range size in roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis> L.): a comparison of two long-term studies

The effect of experimental manipulation of population density on home-range size was investigated in two free-ranging roe deer (Capreolus capreolus) populations under contrasting environmental conditions. In these two long-term monitoring studies, one in Bogesund, Sweden (12 years) and one in Dourdan, France (10 years), deer density varied fourfold through varying culling pressure. Home-range data were collected by radio-tracking across the periods of contrasting density of the studies. We predicted that home-range size for females should vary in relation to the level of feeding competition, while for males, competition for mating opportunities should also influence range size, at least in summer when roe bucks are territorial. We found a highly consistent pattern over the two populations, with strong effects of deer density on home-range size, as well as significant differences between winter and summer ranges and between the sexes. Home ranges were consistently smaller at high density compared to low density. Males had larger ranges than females and this was particularly so during summer. Lastly, winter ranges were generally larger than summer ranges, particularly among females, although males at Dourdan had larger summer ranges compared to winter ranges. We suggest that the reduction of range size at high deer density during winter, as well as summer, is linked to the solitary behaviour and territorial social system of roe deer, with possible effects of dominance rank, even outside the mating season.     

<Emphasis Type="Italic">Ty</Emphasis>1<Emphasis Type="Italic">/copia</Emphasis>- and <Emphasis Type="Italic">Ty</Emphasis>3<Emphasis Type="Italic">/gypsy</Emphasis>-like DNA sequences in <Emphasis Type="Italic">Helianthus </Emphasis>species

Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes.     

Influence of livestock,habitat type,and density of roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) on parasitic larvae abundance and infection seroprevalence in wild populations of roe deer from central Iberian Peninsula

Livestock farming is a common human activity that not only modifies natural habitat but also may lead to interactions with other wild animal species. We studied whether health status of roe deer (Capreolus capreolus) is influenced by density, livestock, and type of habitat. We analyzed 208 samples (120 fecal and 88 sera) from roe deer populations of central Iberian Peninsula to evaluate both presence and abundance of parasitic oocysts, eggs, and/or larvae, especially of gastrointestinal and bronchopulmonary parasites, as well as the prevalence of five infectious diseases (infectious bovine rhinotracheitis (IBR), pestivirosis (BVD/BD), paratuberculosis (PTB), bluetongue (BT), and brucellosis). Fecal samples were collected in transects in pine and oak forests and endoparasites were detected by means of coprological techniques. Serum samples were obtained from hunted individuals and the serological testing for the infectious pathogens was performed by ELISA and Rose Bengal tests. Livestock and habitat type were associated both with the presence and the number of bronchopulmonary nematode L1-larvae per gram of feces (lpg), which was higher in areas with livestock and in pine forests. However, roe deer density neither influenced parasite presence nor lpg values. Regarding infectious pathogens, only seropositive samples for PTB and pestivirus were obtained indicating a possible transmission between domestic and wild ungulates in the study area. The low prevalence found is consistent with other studies in the Iberian Peninsula suggesting that roe deer have little contact with the infectious agents studied. Our results highlight that both habitat type and livestock significantly mediate abundance of parasitic larvae in roe deer, being higher under competition scenarios and in habitats of lower quality, a valuable aspect to be considered in future management and conservation strategies.     

Revision of the <Emphasis Type="Italic">Serrulati</Emphasis> species of <Emphasis Type="Italic">Penstemon</Emphasis> section <Emphasis Type="Italic">Saccanthera</Emphasis> subsection <Emphasis Type="Italic">Serrulati</Emphasis>

A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations.     

<Emphasis Type="Italic">Agrobacterium</Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>-mediated transformation of callus cells of <Emphasis Type="Italic">Crataegus</Emphasis><Emphasis Type="Italic">aronia</Emphasis>

A genetic transformation system has been developed for callus cells of Crataegus aronia using Agrobacterium tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with 5 mg l⁻¹ Indole-3-butyric acid (IBA) and 0.5 mg l⁻¹ 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red colored callus was obtained on MS medium supplemented with 2 mg l⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l⁻¹ kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l⁻¹ hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this is the first time to report an Agrobacterium-mediated transformation system in Crataegus aronia.     

Tick infestation (Acari: Ixodidae) in roe deer (<Emphasis Type="Italic">Capreolus capreolus</Emphasis>) from northwestern Spain: population dynamics and risk stratification

During the 2007 and 2008 hunting seasons (April–October) the skin of 367 roe deer (Capreolus capreolus L.), hunted in different preserves from Galicia (Northwestern Spain), were examined for ticks (Acari: Ixodidae). The overall prevalence of infestation by ticks was 83.1%. The predominant species was Ixodes ricinus (83.1%), whereas a single Dermacentor marginatus specimen appeared in one roe deer. All developmental stages of I. ricinus were found parasitizing roe deer, the adults being the most frequent (82.2%), followed by nymphs (45.6%) and larvae (27.2%). The mean intensity of infestation by I. ricinus was 43.2 ± 49.85; most of them were adults (30.7 ± 31.64) and in a lesser extend nymphs (16.9 ± 24.74) and larvae (10.7 ± 29.90). Ixodes ricinus was present all over the study with percentages that oscillated between 100% in spring and 57.4% in autumn. CHAID algorithm showed the sex of roe deer as the most influential factor in tick prevalence, followed by the climatic area. The different developmental stages of I. ricinus were more frequent in males than in females, and the prevalence of adults and larvae were higher in roe deer from coastal areas than in those from mountainous and central areas, whereas nymphs were more frequent in mountainous areas. Host age and density were not determinants for tick infestation. Our results confirm that roe deer are important hosts for I. ricinus in northwestern Spain, serving as a vehicle for the geographic distribution of these ticks.