Seasonal cycles in the output of first stage larvae of the nematode Elaphostrongylus rangiferi from reindeer,Rangifer tarandus tarandus

Summary The output of first stage larvae of the neurotrophic nematode Elaphostrongylus rangiferi was studied both in a herd of reindeer in the field and in reindeer held in captivity. There was a marked seasonal cycle in the output of larvae from infected reindeer. This seasonal cycle is dependent on host sex. After an initial phase of logarithmic increase from the onset of patency in late winter/spring, the larval output declines to a minimum in summer in both female and male reindeer. From then onwards a yearly cycle is repeated with a maximum density of larvae in autumn/early winter from male reindeer, and in late winter/spring from female reindeer. E. rangiferi has an adult longevity of several years in the reindeer, and it is probable that the seasonal cycle of parasite output is linked to seasonal changes in the degree of host stress.     

Density-dependent effects in a parasitic nematode,Elaphostrongylus rangiferi,in the snnail intermediate host

Summary Density-dependent effects in Elaphostrongylus rangiferi, a parasitic nematode in the CNS and muscular system of reindeer, were studied in a laboratory population of the snail intermediate host, Arianta arbustorum. The rates in parasite growth, development and mortality were all affected by parasite density. The effects on growth and development were, however, much more marked, than the effect on mortality.All density-dependent rates were intensified by decreasing snail size, and by snail starvation. The snail host showed marked tissue reactions against infection, and the intensity of these reactions increased with increasing parasite density. The mechanism behind the observed density-dependent rates is discussed, and is tentatively concluded to be competition for nutritive substances in the host tissue.The importance of a density-dependent developmental rate in natural populations of this parasite is discussed, and it is hypothesized that this effect may counteract the strong temperature-dependent developmental rate of E. rangiferi In a more general context it is pointed out that density-dependent developmental rates, although common amongst animal populations, has been neglected in models of population dynamics. Developmental rates are usually represented by a constant time lag in such models, but should be treated as a density-dependent variable.     

Escaping parasitism in the selfish herd: age, size and density-dependent warble fly infestation in reindeer

It has been suggested that animals may escape attack from mobile parasites by aggregating in selfish herds. A selfish herd disperses the risk of being attacked among its members and the per individual risk of parasite infection should therefore decrease with increasing animal density through the encounter–dilution effect. Moreover, in a selfish herd, dominant and agile animals should occupy the best positions and thereby receive fewer attacks compared to lower ranked animals at the periphery. We tested these predictions on reindeer ( Rangifer tarandus tarandus ) parasitized by warble flies ( Hypoderma tarandi ). Warble flies oviposit their eggs on reindeer during summer and induce strong anti-parasitic behavioural responses in the herds. In this period, reindeer are sexually segregated; females and calves form large and dense herds while males are more solitary. After hatching, the warble fly larvae migrate under the skin of their host where they encyst. In the present study encysted larvae were counted on newly slaughtered hides of male calves and 1.5 year old males from 18 different reindeer herds in Finnmark, northern Norway with large contrasts in reindeer density. In reindeer, body mass is correlated with fitness and social status and we hypothesized that individual carcass mass reflected the animal's ability to occupy the best positions within the herd. Larval abundance was higher among the 1.5 year old males than among the calves. For calves we found in accordance with the selfish herd hypothesis a negative relationship between larval abundance and animal density and between larval abundance and body mass. These relationships were absent for the 1.5 year old males. We suggest that these differences were due to different grouping behaviour where calves and females, but not males, aggregated in selfish herds where they escaped parasitism.     

Elaphostrongylus rangiferi: Influence of temperature,substrate, and larval age on the infection rate in the intermediate snail host, Aarianta arbustorum

The infection rate of the first stage larval nematodes, Elaphostrongylus rangiferi, was studied experimentally, using the juvenile snail Arianta arbustorum as intermediate host. The nematode showed a linear, fivefold increase in infection rate within the temperature range of 4 to 28 C. The snails were exposed to the larval nematodes on three different substrates. The highest infection rate was recorded when snails were exposed in tap water and significantly slower infection rates were obtained when either lettuce or soil was used as the substrate. First stage larvae of E. rangiferi were infective for at least 2 months when stored at 12 C. Throughout this period, the infection rate showed a significant decline, while the motility of the larvae remained unchanged.     

The effect of domestic sheep on forage plants of wild reindeer; a landscape scale experiment

Domestic herbivores often compete with wildlife for limited resources, and on longer time-scales, grazing may also increase or decrease coverage of important food plants to wildlife affecting the threshold density for when competition can be expected. In Norway, there are growing concerns about the effect of releasing 2.1 million domestic sheep (Ovis aries) for summer grazing into areas hosting wild populations of alpine reindeer (Rangifer tarandus). We quantified the effect of sheep grazing (0, 25 and 80 sheep/km²) on the development in coverage and abundance of plants known to be important in the diet of reindeer during summer (vascular plants) and winter (lichens) within a fully replicated, landscape scale (2.7 km²) experiment. From 2001 to 2005, the sedge, Carex bigelowii, increased while the herb Solidago virgaurea decreased in frequency at high density of sheep relative to controls (both marginally non-significant). There was no marked development in Deschampsia flexuosa, Salix herbacea or Hierarcium alpinum that could be related to sheep grazing intensity. Lichen coverage and height both decreased at high density of sheep from 2002 to 2005. Effects of low grazing intensity were closer to controls than to high grazing intensity. Our study highlights that high sheep grazing intensity induce changes to the plant community that, at the same time, can improve the summer habitat and detriment the winter habitat to reindeer. Many wild reindeer populations are fragmented and may thus be limited by either summer or winter range. The effect of sheep grazing is predicted to vary accordingly. However, currently, we have limited ability to quantify how much this explicitly means in terms of increased or reduced carrying capacity for reindeer.     

Black spot infection in juvenile steelhead trout increases with stream temperature in northern California

Climate change will increase water temperature in rivers and streams that provide critical habitat for imperiled species. Warmer water temperatures will influence the intensity and nature of biotic interactions, including parasitism. To better understand the factors influencing a neascus-type parasitic infection known as black spot disease, we examined the relationship between infection rate in juvenile steelhead trout (Oncorhynchus mykiss), abundance of another intermediate host (ramshorn snail, Planorbella trivolvis), and water temperature. We quantified infection patterns of trout at seven sites within the South Fork Eel River in northern California, visiting each site on three different occasions across the summer, and recording water temperature at each site. We also quantified infection patterns in trout captured from two tributaries to the South Fork Eel River. Overall, trout infection rates were highest in sites with the warmest temperatures. The abundance of ramshorn snails was positively related to both water temperature and black spot infection rates in juvenile trout. Both snail abundance and infection rates increased rapidly above a 23 °C daily maximum, suggesting a threshold effect at this temperature. We suggest that warmer temperatures are associated with environmental and biotic conditions that increase black spot disease prevalence in threatened steelhead trout. A comparison of our results with similar data collected from a more northern latitude suggests that salmonids in California may be warm-adapted in terms of their parasite susceptibility.     

Ecological and morphological characteristics of Ephelota gemmipara (Ciliophora,Suctoria), epibiontic on Eudendrium racemosum (Cnidaria,Hydrozoa) from the Adriatic Sea

The relationship between the suctorian Ephelota gemmipara and the large hydroid Eudendrium racemosum from the North Adriatic Sea has been studied over its full annual cycle. Ephelota gemmipara settles on the perisarc of the hydroid, usually close to the hydranths in order to exploit the hydroid's food discharges. The life cycle of E. gemmipara is influenced by temperature variations and by its relationship with the host. The hydroid shows an active phase in the summer, and it gets through the adverse winter season forming resting stages. In April, when temperature increases, the hydroid starts its active phase and it is colonized by suctorians. From May to September the suctorians produce multiple buds (swarmers) that detach from the parental cells to settle on an Eudendrium colony. The abundance of the suctorian peaks in September, with more than 1.2 million ind. m^?2. Their proliferation coincides with the maximal abundance of their host and the highest water temperatures. On the contrary, sexual reproduction and the encystment occur when the temperature and the abundance of E. racemosum decrease. Lastly, we also report the presence of symbionts such as bacteria and the parasitic protozoans Tachyblaston ephelotensis and Enigmocoma acinetarum.     

A trematode parasite alters growth,feeding behavior,and demographic success of invasive rusty crayfish (Orconectes rusticus)

Nonindigenous species can cause major changes to community interactions and ecosystem processes. The strong impacts of these species are often attributed to their high demographic success. While the importance of enemy release in facilitating invasions has often been emphasized, few studies have addressed the role of parasites in the invasive range in controlling demographic success of potential invaders. Here we examine whether a trematode parasite (Microphallus spp.) can contribute to previously documented alternate states in the abundance of invasive rusty crayfish (Orconectes rusticus) in north temperate lakes in Wisconsin, USA. Microphallus infect O. rusticus after emerging from their first intermediate host, a hydrobiid snail. As previously documented, O. rusticus reduce densities of hydrobiid snails through direct predation and destruction of macrophyte habitat. Therefore, if Microphallus substantially reduce O. rusticus fitness, these parasites may reinforce a state of low crayfish abundance, and, at the other extreme, abundant crayfish may repress these parasites, reinforcing a state of high crayfish abundance. From samples collected from 109 sites in 16 lakes, we discovered (1) a positive relationship between crayfish infection intensity and hydrobiid snail abundance, (2) a negative relationship between parasite prevalence and crayfish abundance, and (3) a negative relationship between parasite prevalence and crayfish population growth. With experiments, we found that infection with Microphallus reduced foraging behavior and growth in O. rusticus, which may be the mechanisms responsible for the population reductions we observed. Overall results are consistent with the hypothesis that Microphallus contributes to alternate states in the abundance and impacts of O. rusticus.     

Thermal constraints on daily patterns of aggregation and density along an intertidal gradient in the periwinkle Echinolittorina peruviana

Variations in environmental temperature have both direct and indirect effects that affect organisms at levels ranging from intra-cellular physiological processes to ecological patterns. These variations are especially important for intertidal marine ectotherms such as littorinids since they alternate between periods of immersion in seawater, and must also experience long periods of emersion. In central Chile, Echinolittorina peruviana is one of the most conspicuous species on rocky intertidal shores, occurring at high tidal levels and in the splash zone. The species is known to resist direct exposure to the sun for long periods, although juveniles tend to be restricted to protected microhabitats. Adults show seasonal variations in abundance and vertical distribution and may form aggregations that have been shown to help reduce water loss and body temperature. In this study, we evaluate the relationship between daily thermal variations throughout the vertical distribution of this species and how these affect the patterns of density and aggregation. Our results suggest that one of the leading determinants of the spatio-temporal variation of density in E. peruviana may be operative temperature (T_O: the amount of stored heat resulting from the balance between heat fluxes into and out of the body, measured with taxidermic mounts mimicking heat transfer properties of the snail). T_O showed a strong negative relationship with density and a strong positive relationship with aggregation in the highest intertidal level monitored. The strength of these relationships decreased in importance at lower levels. While T_O alone cannot explain the abundance of E. peruviana throughout its range of distribution, our results show that it does have a strong influence that should be considered in addition to other ecological factors affecting the density of intertidal littorinids.     

Population Densities,Vegetation Green-Up,and Plant Productivity: Impacts on Reproductive Success and Juvenile Body Mass in Reindeer

Global warming is expected to cause earlier springs and increased primary productivity in the Arctic. These changes may improve food availability for Arctic herbivores, but may also have negative effects by generating a mismatch between the surge of high quality food in the spring and the timing of reproduction. We analyzed a 10 year dataset of satellite derived measures of vegetation green-up, population densities, calf body masses and female reproductive success in 19 reindeer (Rangifer tarandus) populations in Northern Norway. An early onset of spring and high peak plant productivity had positive effects on calf autumn body masses and female reproductive success. In addition, body masses and reproductive success were both negatively related to population density. The quantity of food available, as determined by the onset of vegetation green-up and plant productivity over the summer were the main drivers of body mass growth and reproductive success. We found no evidence for an effect of the speed of spring green-up. Nor did we detect a negative mismatch between early springs and subsequent recruitment. Effects of global warming on plant productivity and onset of spring is likely to positively affect sub-Arctic reindeer.     

Differential effects of reindeer on high Arctic lichens

Abstract. We studied the effects of Svalbard reindeer on the abundance of lichens in Spitsbergen. A survey was carried out in 14 areas with contrasting reindeer densities. Separate cover estimates for crustose, fructose and foliose lichens were taken in each area, and related to the density of reindeer pellet groups, a measure of reindeer density. Dominant macro lichen families were identified in 10 areas, and a full record of macrolichen species was taken in four additional areas. Variation in reindeer density is partially due to past overhunting, and subsequent incomplete recovery, releasing some areas from reindeer grazing for 100–200 yr. The cover of fruticose lichens was negatively related to reindeer pellet group density, indicating suppression by Svalbard reindeer. This makes their impact comparable to other members of the Rangifer genus around the northern hemisphere. The generally recorded low abundance of lichens in the diet of Svalbard reindeer compared to other Rangifer species, therefore, was interpreted as the depletion of fruticose lichens in Spitsbergen, and a subsequent switch to alternative foods. Of all fruticose lichens, Stereocaulon spp. appeared least sensitive to grazing. Crustose and foliose lichen cover was independent of reindeer pellet group density. The cover of crustose lichens was significantly related to latitude, with greater cover in more northern areas. Foliose lichens were more abundant in places where moss cover was high. We conclude that the impact of Svalbard reindeer on lichens is dependent on growth form, with fruticose lichens suffering from grazing, whereas foliose lichens might indirectly benefit from higher densities of reindeer or, like crustose lichens, be controlled by other factors.     

Induced Shift in Ecosystem Productivity? Extensive Scale Effects of Abundant Large Herbivores

Abundant large herbivores can strongly alter vegetation composition, shifting the ecosystem into a lasting state of changed productivity. Previous studies of the effects of abundant reindeer on alpine and arctic vegetation have yielded equivocal results, probably due to differing environmental contexts. To overcome context dependency we devised a large-scale survey in the region of Finnmark, northern Norway, possessing some of the most densely stocked reindeer herds in the world. The effects of reindeer abundance on summer pasture vegetation were assessed by employing a quasi-experimental design, including site fertility as a potential modifier of the reindeer–vegetation interaction. The study design comprised ten pairs of neighboring management districts (encompassing 18,003 km²), where over the two last decades a high-density district on average had reindeer densities more than twice as high and calf weights consistently lower than the low-density district. The abundance of different plant functional groups, ranging from those having facilitating to retarding effects on ecosystem productivity, were quantified by the point intercept method on plots selected according to a hierarchical, stratified random sampling design. Species with strong retarding effects on ecosystem productivity (for example, ericoids) were by far the most abundant. However, we found no consistent effects of reindeer density on their abundance. The most consistent differences between high- and low-density districts were found in plant functional groups with facilitating to neutral effects on ecosystem productivity. In particular, the abundance of N-facilitators, large dicotyledons and grasses were substantially reduced in the high-density districts. However, this reduction was restricted to fertile sites. Thus, reindeer when present at high densities have homogenized the biomass of palatable plants across environmental productivity gradients according to predictions from exploitation ecosystem models. Such reduction of plants with facilitating to neutral effects on ecosystem productivity indicates a reduced state of ecosystem productivity in high-density districts. Electronic supplementary material: The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Distribution patterns of pelagic euphausiids in the East China Sea

Distribution patterns and abundance of the euphausiids were examined in the East China Sea (23°30′ –33°00′N, 118°30′ –128°00′ E) in relation to temperature and salinity. The data were collected in 4 surveys from 1997 to 2000. The density or yield density model was used to predict optimum temperature and salinity of water for euphausiid distribution, and thereafter distribution patterns of euphausiids were determined based on the predicted parameters. Of 23 species, Euphausia pacifica, E. nana, Pseudeuphausia sinica and P. latifrons were numerically dominant. The analyses indicate that Euphausia pacifica is an offshore temperate water species, E. nana is an offshore temperate warm water species, P. sinica is a coastal subtropical water species and P. latifrons is an oceanic tropical water species. The 4 species occupied 4 different water masses, respectively, namely, cold water mass, cold and warm water mixed masses in winter and spring, cold and warm water mixed masses in summer and autumn, and warm water mass, which could be the good designators of individual water masses, respectively. The predicated optimal temperatures for E. tenera, S. carinatum, E. diomedeae, Stylocheiron affine, Nematoscelis sp., N. gracilis, N. atlantica, Stylocheiron sp. and S. suhmii are all > 25°. These species are mainly distributed in southern Kuroshio in winter and spring, Kuroshio, the Taiwan Warm Current and Tsushima Current in summer and autumn, the equatorial waters of Pacific Ocean and the eastern waters of the Taiwan Strait. They are called as oceanic tropical water species. Nematoscelis tenella and T. tricuspidata are referred to as offshore subtropical water species according to their geographic distributions even if they are halobionts. Euphausia sanzoi is considered as a typical offshore subtropical water species, which inhabited waters below 25°. Stylocheiron microphthalma, occupying warm current waters where temperature and salinity are nearly 25° and 34 in summer and autumn, belongs to oceanic tropical water species. In the same way, E. similes, E. mutica, Euphausia sp., E. brevis and E. recurva are classified into offshore subtropical water species in accordance with the optimum temperature and salinity of waters as well as locations and seasons of their occurrence. Optimum temperature, rather than salinity, is a better parameter in determining the distribution patterns of euphausiids.     

Seasonal grazing effects by semi-domesticated reindeer on subarctic mountain birch forests

In northern Fennoscandia, the spatial and temporal grazing practices of semi-domesticated reindeer (Rangifer tarandus tarandus) vary, which implies different grazing effects dependent on natural conditions as well as management regime (i.e., timing and intensity of grazing). We compared density and biomass of main plant groups in semi-dry mountain birch forests exposed to either long-term summer or winter grazing in three reindeer herding districts in the northernmost Finland. Percent plant cover, height, and biomass of reindeer lichens (Cladonia spp.) and dwarf shrubs (Vaccinium uliginosum, Calluna vulgaris, and Betula nana) were lower on summer ranges compared with winter ranges. The biomass of other dwarf shrubs (Vaccinium myrtillus and V. vitis-idaea), and graminoids and herbs, and the % cover of non-vegetated bare soil and litter were, however, higher on summer ranges than on winter ranges. Young mountain birch shoots (Betula pubescens ssp. czerepanovii) were less frequent on summer ranges than on winter ranges. The total leaf biomass under the browsing height of reindeer (<1.5 m) was also lower on summer ranges compared with winter ranges. Especially in drier and nutrient poor mountain birch forests, intensive summer grazing reduces the quantity of lichens and total plant biomass which affects the ecological state and productivity of these forests and also reduces especially their winter grazing value for reindeer. Therefore, in addition to regulating the maximum sustained numbers of reindeer, pasture rotation systems that effectively protect dry and nutrient poor vegetation from summer grazing and trampling should be encouraged.     

福建中部近海浮游动物数量分布与水团变化的关系

根据2009—2010年在福建中部近海24°55'—25°13'N、119°11'—119°32'E水域冬、春、夏3个季节的调查资料,探讨了该水域浮游动物总丰度与生物量的平面分布、季节变化及其与台湾海峡水团变化的关系。结果表明,调查水域浮游动物的数量在冬、春之交变化较大,而在春、夏季变化较小。浮游动物冬、春两季的平均丰度分别为8.90 个/m³和245.65 个/m³,夏季为236.82 个/m³。冬、春两季,该水域浮游动物的分布特征相近。其数量在近岸较高,向外侧水域逐渐降低。冬季浮游动物的丰度最高为31.56 个/m³,春季最高达到831.67 个/m³。中华哲水蚤(Calanus sinicus)是冬、春季影响总丰度变化最主要的种类。与冬、春季不同,夏季浮游动物的数量在离岸水域较高,丰度最高达1053.13 个/m³,而在近岸较低,最低值仅19.17 个/m³。汉森莹虾(Lucifer hanseni)、双生水母(Diphyes chamissonis)是影响总丰度变化最主要的种类。浮游动物在各季的不同分布特征与台湾海峡的季节性水团变化有关。受季风转换影响,从冬季到夏季,海峡内沿岸流势力逐渐减弱,台湾暖流水势力逐渐增强,并影响到沿岸的水文环境。这导致调查水域内浮游动物的优势种类由暖温种向暖水种演替。由于冬、春季的重要优势种类中华哲水蚤与夏季的汉森莹虾、双生水母具有不同的温度适应性,受不同性质水团的影响,在近岸和离岸水域各自呈现出不同的数量高低。从而进一步影响到各季浮游动物总数量的分布。     

Life history strategy influences parasite responses to habitat fragmentation

Anthropogenic habitat use is a major threat to biodiversity and is known to increase the abundance of generalist host species such as rodents, which are regarded as potential disease carriers. Parasites have an intimate relationship with their host and the surrounding environment and it is expected that habitat fragmentation will affect parasite infestation levels. We investigated the effect of habitat fragmentation on the ecto- and endoparasitic burdens of a broad niche small mammal, Rhabdomys pumilio, in the Western Cape Province, South Africa. Our aim was to look at the effects of fragmentation on different parasite species with diverse life history characteristics and to determine whether general patterns can be found. Sampling took place within pristine lowland (Fynbos/Renosterveld) areas and at fragmented sites surrounded and isolated by agricultural activities. All arthropod ectoparasites and available gastrointestinal endoparasites were identified. We used conditional autoregressive models to investigate the effects of habitat fragmentation on parasite species richness and abundance of all recovered parasites. Host density and body size were larger in the fragments. Combined ecto- as well as combined endoparasite taxa showed higher parasite species richness in fragmented sites. Parasite abundance was generally higher in the case of R. pumilio individuals in fragmented habitats but it appears that parasites that are more permanently associated with the host’s body and those that are host-specific show the opposite trend. Parasite life history is an important factor that needs to be considered when predicting the effects of habitat fragmentation on parasite and pathogen transmission.     

Relationship between temperature and Ceratomyxa shasta -induced mortality in Klamath River salmonids

Water temperature influences almost every biological and physiological process of salmon, including disease resistance. In the Klamath River (California), current thermal conditions are considered sub-optimal for juvenile salmon. In addition to borderline temperatures, these fish must contend with the myxozoan parasite Ceratomyxa shasta , a significant cause of juvenile salmonid mortality in this system. This paper presents 2 studies, conducted from 2007 to 2010, that examine thermal effects on C. shasta -induced mortality in native Klamath River Chinook ( Oncorhynchus tshawytscha ) and coho ( Oncorhynchus kisutch ) salmon. In each study, fish were exposed to C. shasta in the Klamath River for 72 hr and then reared in the laboratory under temperature-controlled conditions. The first study analyzed data collected from a multi-year monitoring project to asses the influence of elevated temperatures on parasite-induced mortality during the spring/summer migration period. The second study compared disease progression in both species at 4 temperatures (13, 15, 18, and 21 C) representative of spring/summer migration conditions. Both studies demonstrated that elevated water temperatures consistently resulted in higher mortality and faster mean days to death. However, analysis of data from the multi-year monitoring showed that the magnitude of this effect varied among years and was more closely associated with parasite density than with temperature. Also, there was a difference in the timing of peak mortality between species; Chinook incurred high mortalities in 2008 and 2009, whereas coho was greatest in 2007 and 2008. As neither temperature nor parasite density can be easily manipulated, management strategies should focus on disrupting the overlap of this parasite and its obligate hosts to improve emigration success and survival of juvenile salmon in the Klamath River.     

Disease transmission in an extreme environment: nematode parasites infect reindeer during the Arctic winter

Parasitic nematodes are found in almost all wild vertebrate populations but few studies have investigated these host-parasite relationships in the wild. For parasites with free-living stages, the external environment has a major influence on life-history traits, and development and survival is generally low at sub-zero temperatures. For reindeer that inhabit the high Arctic archipelago of Svalbard, parasite transmission is expected to occur in the summer, due to the extreme environmental conditions and the reduced food intake by the host in winter. Here we show experimentally that, contrary to most parasitic nematodes, Marshallagia marshalli of Svalbard reindeer is transmitted during the Arctic winter. Winter transmission was demonstrated by removing parasites in the autumn, using a novel delayed-release anthelmintic bolus, and estimating re-infection rates in reindeer sampled in October, February and April. Larval stages of nematodes were identified using molecular tools, whereas adult stages were identified using microscopy. The abundance of M. marshalli adult worms and L4s increased significantly from October to April, indicating that reindeer were being infected with L3s from the pasture throughout the winter. To our knowledge, this study is the first to experimentally demonstrate over-winter transmission of a gastro-intestinal nematode parasite in a wild animal. Potential mechanisms associated with this unusual transmission strategy are discussed in light of our knowledge of the life-history traits of this parasite.     

The role of deer as vehicles to move ticks, Ixodes ricinus, between contrasting habitats

In Europe the most important hosts maintaining Ixodes ricinus tick populations are deer. Therefore, excluding deer by fencing or culling are potential tick management tools. Here we test the hypothesis that deer act as vehicles for moving ticks between two distinct habitats: forest and open heather moorland. We utilised an ideal “natural experiment” whereby forests were either fenced or unfenced to prevent or allow deer to move between habitats. We aimed to test the hypothesis that deer cause a net movement of ticks from high tick density areas, i.e. forests, to low tick density areas, i.e. open moorland. We recorded I. ricinus and host abundance in 10 unfenced and seven fenced forests and their respective surrounding heather moorland. We found that fenced forests had fewer deer and fewer I. ricinus nymphs than unfenced forests. However, we found no evidence that fencing forests reduced I. ricinus abundance on adjacent heather moorland. Thus there was insufficient evidence for our hypothesis that deer cause a net movement of ticks from forest onto adjacent moorland. However, we found that deer abundance generally correlates with I. ricinus abundance. We conclude that fencing can be used as a tool to reduce ticks and disease risk in forests, but that fencing forests is unlikely to reduce ticks or disease risk on adjacent moorland. Instead, reducing deer numbers could be a potential tool to reduce tick abundance with implications for disease mitigation.