Seasonal incidence and ecology of the tick Ixodes ricinus (Acari: Ixodidae) on grazing pastures in Western France

A longitudinal survey was carried out during a 2 year period in Western France to assess the infestation level of grazing pastures byIxodes ricinus ticks. Four farms were visited once a month and each of the grazing pastures was sampled in the centre and at the border using the blanket dragging method. A total of 3562I. ricinus (34 adults, 900 nymphs and 2628 larvae) were collected and the infestation was significantly higher during the first year (p<0.0001). The infestation level byI. ricinus varied between grazing pastures and farms. Grazing pastures in the vicinity of forest were more infested than the others, all through the study. The seasonal distribution of ticks showed peaks, with low fluctuations between farms, years and stages. Tick abundance could not be related to vegetation, but only to the vicinity of woods.     

Interstadial and Infestation Level-dependent Variation in the Transmission Efficiency of Borrelia Burgdorferi from Mice to Ixodes Ricinus Ticks

The efficiency with which the spirochaete Borrelia burgdorferi sensu stricto was transmitted from laboratory mice to larval and nymphal Ixodes ricinus ticks was assessed, using the polymerase chain reaction. The transmission efficiency to nymphs was significantly greater than to larvae when both fed together on the same host. Increased tick infestation levels of mice were correlated with significantly greater engorgement weights and higher B. burgdorferi transmission coefficients from mice to nymphs. These observations indicate that both the feeding success of ticks and the transmission coefficients from host to tick may be influenced by the tick infestation level of an infected host. The infestation level and the relative numbers of each life stage of the tick are factors which should be considered in the design of transmission experiments.     

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.     

Infestation of urban populations of the Northern white‐breasted hedgehog,Erinaceus roumanicus,by Ixodes spp. ticks in Poland

Infestation by the nest‐dwelling Ixodes hexagonus Leach and the exophilic Ixodes ricinus (Linnaeus) (Ixodida: Ixodidae) on the Northern white‐breasted hedgehog, Erinaceus roumanicus (Erinaceomorpha: Erinaceidae), was investigated during a 4‐year study in residential areas of the city of Poznań, west‐central Poland. Of 341 hedgehogs, 303 (88.9%) hosted 10 061 Ixodes spp. ticks encompassing all parasitic life stages (larvae, nymphs, females). Ixodes hexagonus accounted for 73% and I. ricinus for 27% of the collected ticks. Male hedgehogs carried significantly higher tick burdens than females. Analyses of seasonal prevalence and abundance of I. hexagonus revealed relatively stable levels of infestation of all parasitic stages, with a modest summer peak in tick abundance noted only on male hosts. By contrast, I. ricinus females and nymphs peaked in spring and declined steadily thereafter in summer and autumn, whereas the less abundant larvae peaked in summer. This is the first longterm study to evaluate the seasonal dynamics of both tick species on populations of wild hedgehogs inhabiting urban residential areas.     

Ability of transovarially and subsequent transstadially infected Ixodes hexagonus ticks to maintain and transmit Borrelia burgdorferi in the laboratory

In a previous study, transstadial and transovarial survival of Borrelia burgdorferi in Ixodes hexagonus and transmission to laboratory mice via the bite of infected females were demonstrated. Here, we report the ability of I. hexagonus progeny infected transovarially to maintain and transmit the spriochaete to the host.Ticks were examined for spirochaetes by direct immunofluorescence antibody test. I. hexagonus larvae derived from the parental transstadially infected females were fed on two white mice: 21/54 (38.9%) of these ticks examined as unfed nymphs were infected. I. hexagonus nymphs were fed on three white mice and examined for spirochaetes after moulting as adults: 7/25 (28%) were found to harbour the spirochaete. The success of B. burgdorferi transmission to the mice by larval and nymphal I. hexagonus was determined by xenodiagnosis using I. ricinus larvae: 20/50 (40%) and 30/99 (30.3%) of the I. ricinus larvae fed on the mice infected by I. hexagonus larvae and nymphs respectively became infected.This study shows that B. burgdorferi can be maintained through transovarial and subsequent transstadial transmissions in I. hexagonus.     

Utilisation of rodent species by larvae and nymphs of hard ticks (Ixodidae) in two habitats in NE Poland

The impact of host identity and habitat type on the density of hard ticks (Ixodes ricinus and Dermacentor reticulatus) infections on rodents in forest and abandoned field habitats in NE Poland was investigated. Ixodes ricinus was most abundant in the forest system, but D. reticulatus, although rarer, was most abundant in the field system. Environmental humidity and the much lower density of rodents probably limited the abundance of I. ricinus larvae in the field system, although this tick was still common on Microtus oeconomus from around small ponds. Nymphs of I. ricinus were comparatively rare in the forest, probably because of infection of non-rodent hosts. Dermacentor reticulatus nymphs on the other hand were very much more common in the ears of Microtus species than would have been predicted based on larval densities. The impact of habitat change (in this case successional change following field abandonment) on tick densities is emphasised, and the role of Apodemus as an epidemiological bridge, linking woodland and field habitats, is highlighted.     

Tick infestation of small mammals in an English woodland

Tick infestations on small mammals were studied from April to November, 2010, in deciduous woodland in southern England in order to determine whether co‐infestations with tick stages occurred on small mammals, a key requirement for endemic transmission of tick‐borne encephalitis virus (TBEV). A total of 217 small mammals was trapped over 1,760 trap nights. Yellow‐necked mice (Apodemus flavicollis) made up the majority (52.5%) of animals, followed by wood mice (A. sylvaticus) 35.5% and bank voles (Myodes glareolus) 12%. A total of 970 ticks was collected from 169 infested animals; 96% of ticks were Ixodes ricinus and 3% I. trianguliceps. Over 98% of ticks were larval stages. Mean infestation intensities of I. ricinus were significantly higher on A. flavicollis (6.53 ± 0.67) than on A. sylvaticus (4.96 ± 0.92) and M. glareolus (3.25 ± 0.53). Infestations with I. ricinus were significantly higher in August than in any other month. Co‐infestations with I. ricinus nymphs and larvae were observed on six (3.6%) infested individuals, and fifteen small mammals (8.9%) supported I. ricinus – I. trianguliceps co‐infestations. This work contributes further to our understanding of European small mammal hosts that maintain tick populations and their associated pathogens, and indicates that co‐infestation of larvae and nymph ticks does occur in lowland UK. The possible implications for transmission of tick‐borne encephalitis virus between UK ticks and small mammals are discussed.     

Host community structure and infestation by ixodid ticks: repeatability,dilution effect and ecological specialization

Abundance of a species in a location results from the interplay between the intrinsic properties of that species and the extrinsic properties, both biotic and abiotic, of the local habitat. Intrinsic factors promote among-population stability in abundance, whereas extrinsic factors generate variation among populations of a species. We studied (a) repeatability and (b) the effect of abundance and species richness of small mammals on the level of their infestation by larvae and nymphs of Ixodes ricinus (ecological generalist) and Ixodes trianguliceps (ecological specialist). We asked if tick infestation parameters are characteristic (=repeatable) for a particular host species or a particular stage of a particular tick species. We also asked how abundance and diversity of hosts affect the level of tick infestation on a particular host species. We predicted that the dilution effect (decrease in tick infestation levels with an increase of host abundance and/or species richness) will be better expressed in an ecological generalist, I. ricinus, than in an ecological specialist, I. trianguliceps. We found that (a) tick abundance, prevalence and aggregation were generally repeatable within tick species/stage; (b) tick abundance and prevalence, but not the aggregation level, were repeatable within host species; (c) the proportion of variance among samples explained by the differences between tick species and stages (as opposed to within-tick species and stage) was higher than that explained by the differences between host species (as opposed to within host species); and (d) the relationship between tick infestation parameters and host abundance and diversity revealed the dilution effect for I. ricinus but not for I. trianguliceps.     

Vector competence of Ixodes angustus (Acari: Ixodidae) for Borrelia burgdorferi sensu stricto

The vector competence of Ixodes angustus for Borrelia burgdorferi sensu stricto (s.s.) was investigated in the laboratory. The larval progeny of female ticks from Washington State were placed on Swiss-Webster mice that had been inoculated intravenously with 10⁸ spirochetes each of a Californian isolate of B. burgdorferi. Spirochetes were detected in 6 (12%) of 50 nymphs derived from larvae that had fed on these animals. Ten nymphs from the same cohort of experimentally infected ticks were placed on each of 4 naive deer mice (Peromyscus maniculatus). One of the mice seroconverted to B. burgdorferi and spirochetes were isolated from its ear tissues 4 weeks after exposure to ticks. Further vector competence trials were conducted with I. angustus ticks from California. Larvae were fed on deer mice that had been inoculated intradermally with B. burgdorferi along with larvae of I. spinipalpis as a comparison group. There was no significant difference in the prevalence of infection in nymphs of I. angustus (8.2%) versus those of I. spinipalpis (12.1%). We conclude that I. angustus is a competent experimental vector of B. burgdorferi s.s. and its efficiency for acquiring and transstadially passing such spirochetes is similar to that of I. spinipalpis.     

Borrelia burgdorferi sensu lato in ticks (Acari: Ixodidae) from two different foci in Spain

The prevalence of Borrelia burgdorferi sensu lato in several tick species was studied over a 2 year period in two ecologically different areas in Spain. One area was an endemic area for Lyme disease, with a number of autochthonous human cases and supported large populations of Ixodes ricinus on cattle and birds; the second area was characterized by the absence of I. ricinus together with the presence of foxes and their associated tick species. While I. ricinus was the main vector of B. burgdoreri in the endemic area (with a mean prevalence of 14% in adults and 51% in nymphs), adults of both Ixodes canisuga and Ixodes hexagonus had high rates of B. burgdorferi prevalence (30 and 28%, respectively) in the zone where I. ricinus was absent. Immatures of Ixodes frontalis were found to be carriers of the spirochete only in those zones where I. ricinus is present, suggesting evidence for reservoir competence in a tick-bird cycle.     

Entomopathogenic fungi associated with Ixodes ricinus ticks

The objective of this study was to demonstrate the occurrence of entomopathogenic fungi on Ixodes ricinus ticks in relation to the tick stage, engorgement and season. Ticks were collected from the vegetation, from small rodents and from deer. All entomopathogenic fungi found belonged to the Hyphomycetes. Paecilomyces farinosus and Verticillium lecanii were the predominant species. Other species, found only on engorged females were: Beauveria bassiana, B. brongniartii, P. fumosoroseus and V. aranearum. Eight out of 1833 ticks collected from the vegetation and three out of 269 engorged nymphs were infected with fungi. Thirty-three out of 149 engorged females were infected, whereas males and engorged larvae were not infected. Throughout the season, a significantly higher proportion of ticks collected in autumn were infected. Entomopathogenic fungi may have a significant impact on the size of the I. ricinus population, since females were the most frequently infected stage.     

Molecular Detection of Murine Herpesvirus 68 in Ticks Feeding on Free-living Reptiles

The MHV-68 (designed as Murid herpesvirus 4 (MuHV 4) strain 68) isolated from two rodents, Myodes glareolus and Apodemus flavicollis, is considered as a natural pathogen of free-living murid rodents. Recently, the detection of MHV antibodies in the blood of animals living in the same biotope as MHV-infected mice has suggested that ticks may have a role in the transmission of this pathogen. Ixodes ricinus is one the most abundant tick species in Europe known to transmit multiple pathogens causing human and animal diseases. In this study, nymphs and larvae feeding on 116 individuals of a temperate lizard species—the green lizard Lacerta viridis captured in the Slovak Karst National Park, were examined for MHV-68. The specific sequence of virion glycoprotein 150 was amplified in DNA individually isolated from I. ricinus ticks using single-copy sensitive nested polymerase chain reaction. MHV-68 was detected in ten of 649 nymphs and in five of 150 larvae, respectively. We found that 9.6% of green lizards fed at least one MHV-68-infected immature tick. Occurrence of MHV-68 within all ticks tested was 1.8%. This study is first to show that immature I. ricinus ticks feeding on free-living lizards in a Central European region could be infected with gammaherpesvirus (MHV-68), naturally infecting free-living murid rodents. Our results provide evidence supporting the hypothesis that ticks may play a mediating role in circulation of MHV-68 in nature.     

Risk indicators for the tick Ixodes ricinus and Borrelia burgdorferi sensu lato in Sweden

The distributional area of the tick Ixodes ricinus (L.), the primary European vector to humans of Lyme borreliosis spirochaetes (Borrelia burgdorferi sensu lato) and tick‐borne encephalitis virus, appears to be increasing in Sweden. It is therefore important to determine which environmental factors are most useful to assess risk of human exposure to this tick and its associated pathogens. The geographical distribution of I. ricinus in Sweden was analysed with respect to vegetation zones and climate. The northern limit of I. ricinus and B. burgdorferi s.l. in Sweden corresponds roughly to the northern limit of the southern boreal vegetation zone, and is characterized climatically by snow cover for a mean duration of 150 days and a vegetation period averaging 170 days. The zoogeographical distribution of I. ricinus in Sweden can be classified as southerly–central, with the centre of the distribution south of the Limes Norrlandicus. Ixodes ricinus nymphs from 13 localities in different parts of Sweden were examined for the presence of B. burgdorferi s.l. and found to be infected with Borrelia afzelii and Borrelia garinii. Tick sampling localities were characterized on the basis of the density of Borrelia‐infected I. ricinus nymphs, presence of specific mammals, dominant vegetation and climate. Densities of I. ricinus nymphs and Borrelia‐infected nymphs were significantly correlated, and nymphal density can thus serve as a general indicator of risk for exposure to Lyme borreliosis spirochaetes. Analysis of data from this and other studies suggests that high densities of Borrelia‐infected nymphs typically occur in coastal, broadleaf vegetation and in mixed deciduous/spruce vegetation in southern Sweden. Ixodes ricinus populations consistently infected with B. burgdorferi s.l. can occur in: (a) biotopes with shrews, rodents, hares and birds; (b) biotopes with shrews, rodents, hares, deer and birds, and (c) island locations where the varying hare (Lepus timidus) is the only mammalian tick host.     

Tick infestation risk and <Emphasis Type="Italic">Borrelia burgdorferi</Emphasis> s.l. infection-induced increase in host-finding efficacy of female <Emphasis Type="Italic">Ixodes ricinus</Emphasis> under natural conditions

An investigation of the risk of human tick infestation, together with the prevalence of Borrelia burgdorferi s.l. infection, was conducted in a sylvatic habitat in western Germany to provide data needed for future risk-benefit evaluations of acaricides used for clothing impregnation. Additionally, data were collected on behavioural changes in Borrelia burgdorferi s.l.-infected adult female I. ricinus ticks and the possible impact of such changes on host-finding efficacy. The risk of I. ricinus-infestation was determined by collecting from the protective clothing of volunteers and by dragging in known tick-infested sites in the Kühkopf Mountain area, Koblenz, Germany, from June through October 2006. The overall tick infestation rate per person per hour was 7.4 ± 5.5, with the following sex- and stage-specific differences: males 0.32 ± 0.37, females 1.1 ± 1.2, nymphs 3.6 ± 4.4, larvae 2.4 ± 3.5. Concurrent dragging revealed an average 19.4 ± 16.2 times higher infestation rate as well as a markedly lower infection rate with borreliae in adult I. ricinus ticks when compared to ticks collected from exposed human volunteers. Although the difference in infection rates was statistically significant (P < 0.023) only in adult female ticks, our data indicate that B. burgdorferi s.l. infection may increase host-finding efficacy in adult I. ricinus. The overall exposure risk was 1.0 B. burgdorferi s.l.-infected ticks per person per hour of exposure, or 0.25 ticks per 100 m walking distance in the study area.     

Relative importance of lizards and mammals as hosts for ixodid ticks in northern California

Lizards and mammals were trapped and examined for ticks from August 1992 to June 1993 in two habitat types, chaparral and woodland-grass, in northern California. Five tick species were collected from mammals (Dermacentor occidentalis, Haemaphysalis leporispalustris, Ixodes pacificus, I. spinipalpis, I. woodi), but only I. pacificus was found on lizards. Dermacentor occidentalis, I. pacificus, and I. woodi occurred in both habitats, whereas H. leporispalustris and I. spinipalpis were found only on animals trapped in chaparral. The tick species most commonly encountered on mammals was D. occidentalis in chaparral and I. pacificus in woodland-grass. Peak infestation of mammals occurred in spring for I. pacificus immatures and H. leporispalustris, summer for D. occidentalis immatures, fall through spring for I. woodi immatures, and fall through winter for I. spinipalpis. The primary aim of the study was to quantify the relative importance of the western fence lizard (Sceloporus occidentalis), which is reservoir-incompetent for Borrelia burgdorferi sensu lato (s.l.), and mammalian B.burgdorferi s.l.-reservoirs as hosts for the immature stages of I. pacificus in spring. The estimated relative utilization by I. pacificus of the western fence lizard versus mammals was 88% for larvae and 99% for nymphs in chaparral in May. When tick infestation data were corrected for a two-fold lower efficiency of field examinations for rodents than for lizards, the western fence lizard still accounted for 78% of larval and 98% of nymphal feedings. In woodland-grass, 46% of 100 I. pacificus larvae and 100% of 52 nymphs recovered from mammals or western fence lizards during May-June were collected from the lizards. However, this may represent an underestimate of the importance of the western fence lizard as a larval host in this habitat because inclement weather during the late May sampling period doubtless resulted in significantly decreased lizard activity. In conclusion, the western fence lizard was more heavily utilized by I. pacificus immatures, especially nymphs, than were rodents. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lyme borreliosis spirochetes in Ixodes ricinus and Haemaphysalis punctata ticks (Acari: Ixodidae) on three islands in the Baltic Sea

The prevalence of infection with Lyme borreliosis spirochetes in nymphal Ixodes ricinus and Haemaphysalis punctata was examined on three Swedish islands in the Baltic Sea. The proportion of H. punctata nymphs infected with Borrelia spirochetes (2%) was lower than that of I. ricinus nymphs (11–16%), even on the island of Stora Karlsö where both tick species feed on the single mammalian host present, the varying hare, Lepus timidus. Ten of the 12 infected questing H. punctata nymphs harboured very few spirochetes, whereas the remaining two harboured as many as 30–40 spirochetes. However, it remains to be seen whether H. punctata nymphs are capable of transmitting spirochetes during their blood meal and, thus, serving as vectors for Lyme borreliosis spirochetes. On Gotland and Fårö, I. ricinus was more abundant than H. punctata in deciduous and coniferous forest, whereas H. punctata was equally or more abundant than I. ricinus in juniper brush areas on open land. Host preference and biotope usage of H. punctata seems, in general, to prevent this tick from feeding on highly infective Borrelia reservoirs, such as Apodemus mice.     

Diversity,ecology, and seasonality of hard ticks (Acari: Ixodidae) in eastern Croatia

The diversity of hard tick fauna was studied in different forest communities in 48 localities of eastern Croatia using the dragging‐flagging method and by hand from ten different vertebrate hosts. A total of 2,225 specimens comprising seven species in three genera were identified. Ixodes ricinus, the most abundant species (72.8% of all collected specimens) was recorded in 44 localities, followed by Dermacentor reticulatus in 19 localities, while the other five species (D. marginatus, H. concinna, H. inermis, I. canisuga, and I. hexagonus) were recorded in fewer localities. The highest ratio (67% of collected ticks) was in the adult stage with the predominance of females. The numbers of collected females, males, and nymphs of I. ricinus and H. concinna differed significantly. Ten new tick‐host associations in Croatia were recorded. Fifty‐three animals were infested with one tick species. Single species infestation with I. ricinus was found in 45.8% of animals, followed by D. reticulatus with 25.4%, D. marginatus with 10.2%, H. inermis and I. hexagonus with 3.4%, and I. canisuga with 1.7%. Coinfestation with two species of ticks were recorded in six animals. Ixodes ricinus, H. inermis, and D. reticulatus showed bimodal seasonal activity; for other species unimodal activity patterns were recorded.     

Role of small mammals in the ecology of Borrelia burgdorferi in a peri-urban park in north coastal California

The role of small mammals other than woodrats in the enzootiology of the Lyme disease spirochete, Borrelia burgorferi, was assessed in a peri-urban park. Mammals were collected monthly from September through to April. Following tick removal, the animals were tested for B. burgdorferi by culture of ear-punch biopsies. Larvae and nymphs that were intermediate in morphology between Ixodes spinipalpis and Ixodes neotomae occurred on several species of rodents (Peromyscus truei, Peromyscus californicus, Microtus californicus, Rattus rattus and Reithrodontomys megalotis) and the brush rabbit (Sylvilagus bachmani). Morphometric analyses of these I. spinipalpis-like ticks and the offspring from two I. neotomae females from this site suggest that I. neotomae may be conspecific with I. spinipalpis. Borrelia burgdorferi was isolated from eight out of 109 (7.3%), three out of 16 (18.8%), two out of 38 (5.3%) and two out of six (33.3%) P. truei, P. maniculatus, M. californicus and R. rattus, respectively. One brush rabbit yielded the first isolate of B. burgdorferi from a lagomorph in western North America. This isolate and three others derived from unfed I. spinipalpis-like nymphs failed to produce infection when inoculated intradermally into 11–12 P. maniculatus each. Likewise, no spirochetes were detected in 420 Ixodes pacificus nymphs derived from larvae fed on animals inoculated with these isolates. An additional isolate, derived from an I. spinipalpis-like nymph, was recovered by ear-punch biopsies from five out of 12 (42%) needle-inoculated P. maniculatus. However, spirochetes were not detected in 20 I. pacificus nymphs fed as larvae on each of five mice (two infected and three uninfected) inoculated with this isolate. We conclude that brush rabbits and several species of rodents besides woodrats may contribute to the maintenance of B. burgdorferi because they harbour the spirochete and are fed upon by competent enzootic and bridge vectors.     

Hosts and Pathogen Detection for Immature Stages of Ixodes ricinus (Acari: Ixodidae) in North-Central Spain

To determine hosts of the immature stages of a southern population of Ixodes ricinus, we trapped rodents and birds in an area of north-central Spain in May–June and August–September of 1998 and 1999. The most frequently trapped rodents were Apodemus sylvaticus (230 specimens) and Clethrionomys glareolus (99), with a larval infestation prevalence of 49% and 81%, respectively (in spring) and 21% and 41% (in summer). C. glareolus was always more heavily parasitized by larvae (mean numbers 19.8 in spring, 3.4 in summer) than A. sylvaticus (6.1 and 1.2, respectively). No nymphs were collected from the rodents. The larval distribution pattern differed considerably between rodent host species but not according to the season of the year. The most commonly trapped birds were members of the Turdidae, which had infestation incidences of about 70% (larvae) and 10% (nymphs) in spring and 20–15% in summer. We also used molecular methods for the identification of reservoir hosts of the larval ticks and of the pathogens they contained, from nymphs collected in the same site in June of 2002 and 2003. The study showed that most of the ticks had fed on birds and few on rodents and ruminants. Pathogens detected in these ticks included Babesia microti, Borrelia garinii, B. valaisiana and B. afzelii. Borrelia afzelii was detected in a tick that had apparently fed on a wild boar.     

Ixodes ricinus parasitism of birds increases at higher winter temperatures

Increasing winter temperatures are expected to cause seasonal activity of Ixodes ricinus ticks to extend further into the winter. We caught birds during winter months (November to February) at a site in the west of Scotland over a period of 24 years (1993–1994 to 2016–2017) to quantify numbers of attached I. ricinus and to relate these to monthly mean temperature. No adult ticks were found on any of the 21,731 bird captures, but 946 larvae and nymphs were found, with ticks present in all winter months, on 16 different species of bird hosts. All ticks identified to species were I. ricinus. I. ricinus are now active throughout the year in this area providing temperature permits. No I. ricinus were present in seven out of eight months when the mean temperature was below 3.5º C. Numbers of I. ricinus attached to birds increased rapidly with mean monthly temperatures above 7º C. Winter temperatures in Scotland have been above the long‐term average in most years in the last two decades, and this is likely to increase risk of tick‐borne disease.