Wild badgers (Meles meles) in Wytham woods, Oxfordshire, are routinely trapped, transported to a central field laboratory, studied and released as part of an on-going population study. These procedures have been carefully developed to minimise impact on the badgers' welfare; however they are potentially stressful, and, as part of our on-going welfare refinements, and our exploration to develop methods for quantifying stress in wild mammals, we studied the effects of transport stress on neutrophil activation in wild trapped badgers. Blood samples were obtained from 28 badgers. We compared three transport regimes: transported (n = 9), transported and rested for at least 30 mins (n = 11), and not transported (n = 8). Total and differential white cell counts were carried out and neutrophil activation was measured by the nitroblue tetrazolium test. Our goal was primarily to validate neutrophil activity as an indicator of stress, on the basis that the transport treatment was expected to be more stressful than the non-transport treatment. There were significant increases in % activated circulating neutrophils in response to transport. This study supports the proposition that stress affects circulating neutrophil numbers and the state of their activation, as determined by the nitroblue tetrazolium reduction assay, and therefore adds weight to the idea that neutrophil activation is a potential measure of stress in wild animals.

Babesia are intraerythrocytic parasites of importance worldwide within the fields of human and veterinary medicine, as some Babesia sp., including Babesia microti are potentially zoonotic and can cause fatal disease in both humans and animals. The aims of this study were to use a nested PCR (amplifying the 18S rRNA gene) to determine the presence and species of Babesia parasite DNA found in blood (n = 47) and spleen (n = 47) samples collected from Eurasian badgers (Meles meles) in Scotland. The results showed 28/47 (59·6%) blood and 14/47 (29·8%) spleen samples tested positive for the presence of Babesia DNA. Initial sequence analysis of the Babesia DNA identified three distinct sequence types (submitted to GenBank KX528553, KX528554 and KX528555), which demonstrated ⩾99% identity to Babesia sp. parasites previously identified in badgers in Spain (KT223484 and KT223485). Phylogenetic analysis showed that the three isolates are closely related to Babesia annae, B. microti and other Piroplasmida species found in wildlife. Further sequence analysis of the samples demonstrated that the badgers were routinely infected with more than one parasite isolate and there was also evidence of genetic recombination between the Babesia parasite isolates (submitted to GenBank KY250472 – KY250477)

Sarcocysts from the tongue muscle of a European badger (Meles meles) are reported for the first time and described by light and transmission electron microscopy. Judging from the ultrastructure of the cyst wall, the parasite is similar to the species Sarcocystis gracilis Rátz, 1909 sensu Erber, Boch & Barth (1978) from roe deer and possibly identical with it. This is noteworthy regarding the intermediate host specificity.

In our study three badger Meles meles populations separated by only a few km but subjected to different environmental conditions were compared. Differences are especially marked for climatic factors, the three areas being located at different altitudes, and for intensivity of soil use by people. The diet of the three populations was significantly different, with one or two dominant items in each area: mammals and cereals in the mountain, maize in the mid-mountain and in the lowland areas. In the most intensively cultivated area, maize was the most consumed item in autumn and spring, several months after harvesting. Earthworms had only a secondary importance in the diet in the mountainous area, but were negligible in the mid-mountain and lowland areas. Soil management seemed to play a preponderant role, mostly owing to soil quality and topography. Climate seemed to have a secondary effect only.

Distance sampling is a common and increasingly used method of estimating animal abundance in conservation and management programmes. The precision of a distance sampling survey can be estimated from the field data, but accuracy can only be evaluated by comparison with the true population size. For wild mammal populations, such opportunities are rare. The high-density badger Meles meles population at Woodchester Park in Gloucestershire, U.K. has been routinely and intensively live-trapped for the past 30 years. The estimates of abundance based on mark–recapture analyses of the live-trapping data provided a reliable baseline against which to evaluate distance sampling for a badger population. A distance sampling survey was carried out in autumn 2002 by using spotlighting along line transects. Owing to the impractical nature of spotlighting in closed habitats, such as woodland, surveys were conducted in open habitat only. A radio-tracking study provided behavioural data that were used to estimate the proportion of the population available for sampling in open habitats. This was incorporated as a multiplier into the DISTANCE analysis. The estimate of abundance from distance sampling was 76 badgers (% CV=42.2), using a multiplier based on radio-tracking data from autumn only. When the multiplier was derived from radio-tracking data from across the whole year, based on a larger sample of tracked badgers, the distance sampling abundance estimate was 77 badgers (% CV=25.9). These compared favourably to the mark–recapture estimate of 68 badgers (% C.V=7.4). The lack of precision in the distance sampling density estimate was largely owing to the inclusion of the multiplier. Distance sampling combined with data on habitat use can produce reliable estimates of badger abundance in areas of medium to high density, particularly in landscapes of primarily open habitat.

During the past 50 years the number of badgers (Meles meles) in Denmark has declined by c. 50%. To assess the genetic consequences of the demographic decline, six DNA-microsatellite loci were used to analyse 139 badger tissue-samples, which were collected in 1995–98 from three zones (1, 2 and 3) in Jutland (Denmark). Results from contemporary samples were compared to data obtained from DNA extracted from teeth belonging to 39 badgers collected from zones 1 and 2 in 1957–66. The microsatellites showed a low to moderate polymorphism, and the within area genetic diversity (HE) was relatively low (0.308≤HE≤0.441) as compared to other carnivores and mustelids. Genetic differentiation among the three recent sampling zones was significant (FST=0.072, P<0.0001). The FST values between the two recent (FST=0.092, P<0.0001) and the two historical samples (zones 1 and 2; FST=0.073, P<0.0001) were significant and similar. The HE and FST of the recent and historical zones were not significantly different (P>0.05). Despite the drastic recent decline, Danish badgers did not show apparent signs of genetic bottlenecks in both recent and historical samples. The use of molecular techniques which allowed us to work with small amounts of degraded DNA extracted from old teeth, allowed us to exclude the hypothesis that genetic differentiation between zones 1 and 2 was owing to a barrier, which has appeared in the last 50 years. Furthermore, the low genetic variability and therefore the relatively high genetic differentiation shown by Danish badgers were also shown not to be the result of the recent drastic population decline.

Interspecific interactions between sympatric carnivores have important implications for intra-guild competition, epidemiology (here especially in the context of rabies and bovine tuberculosis), and strategies for species-specific population management. Data are provided on 135 interspecific encounters between at least 35 European badgers Meles meles and a minimum of five red foxes Vulpes vulpes, gathered with the aid of remote video surveillance at an artificial feeding site, and in the vicinity of six badger setts. We hypothesized that interspecific competition would be manifest in aggression and changes in vigilance and feeding, with the larger badger having the advantage, and we sought to explore differences in any such changes at the two types of site. Badgers were clearly dominant over foxes, fed in longer bouts and were less vigilant. At badger setts, once it was clear that the encounter was not going to escalate to aggression, each species was unaffected by the presence, proximity or orientation of the other. There are preliminary indications that foxes sometimes seek the company of badgers.

This paper examines the relationship between the number of occupied setts in a badger social group territory and badger group size, breeding success, and status of infection with Mycobacterium bovis (TB). The data used were from a long-term epidemiological and ecological study of a high-density population of badgers Meles meles in south-west England. The number of occupied setts in a social group was significantly and positively related to the number of badgers caught in the social group, so that as a social group increases in size, badgers occupy more of the available setts. This relationship remained significant when numbers of adults, adult males and adult females were examined. The number of breeding females, number of cubs and sex ratio was not related to the number of occupied setts in a social group. It is possible that the advantages to breeding females of a larger number of setts available to breed in might be outweighed by the increased aggression found in larger groups. The TB score for prevalence and for incidence of social groups was significantly and positively related to the number of occupied setts in a social group, such that the more occupied setts there were in a territory, the higher the TB index of the group. Possibly the setts themselves contribute to the persistence of TB within social groups, or badgers infected with TB might show a difference in behaviour from uninfected badgers resulting in their increased use of outlying setts.

Estimating the size of badger populations at a local scale using direct observation is difficult because of their nocturnal and elusive lifestyle. Methods based on live-trapping can provide robust estimates of badger numbers, but are very labour-intensive and expensive. The development of alternative methods to predict badger numbers accurately would provide valuable tools for research and management. Badger setts are distinct structures, which exhibit various signs of activity. The physical appearance of setts has been used in the past as a crude guide to the number of badgers likely to be trapped. In this study, an objective system for quantifying levels of activity at badger setts was developed and related to the number of trapped badgers. Several types of activity were positively associated with badger numbers, although these associations varied seasonally. Furthermore, all individual activity scores, summary indices and combinations of activity types were poor predictors of the number of badgers trapped. This is probably because variations in environmental conditions and badger behaviour confound the relationship between activity and badger numbers.

This study assesses the pattern of occurrence of a generalist species, the Eurasian badger Meles meles, in forest fragments located in agricultural landscapes of central Spain with a coarse-grained pattern of fragmentation (<20% forest cover in the landscape). Four forest regions (n = 139 forest fragments) were sampled. Badger presence/absence in forest fragments was studied in relation to: forest size, isolation and vegetation structure. Badgers were tested to see if, despite their habitat generalism, they were negatively affected by forest fragmentation in this type of fragmented landscape. Results indicated a strong and significant effect of fragment size on badger occurrence (presence was rare in forest fragments <100 ha) and an important effect of isolation at a local scale. The response of badgers to forest fragmentation in Spain is quite different to the response in other European landscapes. In Spain, badgers cope with a divided coarse-grained landscape where suitable habitats are embedded in a largely unsuitable matrix (cereal croplands). In contrast, in Britain or central Europe, badgers may be benefited by forest clearances in a heterogeneous but non-divided landscape where small woodlots are separated by a matrix of good quality (mainly pastures) and fragmentation produces fine-grained mosaic landscapes where food and den sites are simultaneously enhanced. Species' response to forest fragmentation may strongly depend on the pattern of fragmentation and, in coarse-grained fragmented landscapes, generalist species may be affected in the same way as specialist ones.

The relationships between radio-collaring/tracking and 12 biometric parameters in a population of badgers (Meles meles) that were live-trapped in south-west England were investigated. The length of time for which a badger had worn a radio-collar was selected as an explanatory variable in generalized linear models of three biometric parameters (body condition, body weight and testes volume) irrespective of whether or not age class was included as a variable in the analyses. There was evidence that badgers that had been carrying a radio-collar for 1–100 days had lower body condition scores both when compared to badgers that had not been collared and with those that had been collared for longer than 100 days, suggesting a post-collaring acclimation period. In addition, the time period between first and last capture was longer for radio-collared than non-collared badgers. It is unlikely that this was due to an effect of collaring on trappability or to non-random selection of badgers for collaring. Although testes size differed between non-collared badgers and badgers that had been tagged for > 100 days, the relationship between radio-collaring and reproductive output remained unproven. These results highlight not only the need to assess the welfare aspects of radio-collaring but also the potential intricacy of corollaries of collaring. Explorations such as that reported here are important to the validity of studies that make use of radio-telemetry.

Between 1987 and 1996 the numbers of badgers Meles meles in Wytham Woods rose from 60 to 228 adults. The area occupied by the population has not changed and thus density has also risen from 10 adult badgers/km2 to 38/km2. This rise parallels an increase in badger abundance seen across Britain in recent years. The hypothesis that this increase is either the consequence of improved badger protection or of changes in habitat can be rejected for this site. Instead, a link between increasing numbers and changing weather patterns, possibly resulting from climate change, is investigated. In particular, attention is drawn to a correlation between mild winters and heavier body weights of badgers in January. Furthermore socio-spatial restructuring within the population may be the mechanism that has permitted high density to be sustainable. The increase in badger numbers at Wytham has not affected population sex ratio, which has remained relatively constant at parity throughout the study.

We describe diurnal resting dens (setts) used by Eurasian badgers Meles meles L. in Coto del Rey, Doñana National Park, south-western Spain, and analyse the factors that determine sett location and selection in relation to territory outlines, soil type and vegetation structure. Setts were located by tracking radio-tagged badgers daily. Badger setts were mainly underground burrow systems with, on average, 2.6 badger entrances. Frequently, badgers constructed setts by enlarging existing rabbit warrens. Setts were located almost everywhere, but badgers preferred easily dug, well-drained soils with good vegetation cover within foraging habitats. A logistic regression model showed that badgers select sites with high surrounding shrub density, large shrubs covering the burrow and close to the centre of the territory (in Mediterranean scrubland habitat). The small size of badger setts in Coto del Rey is common to other low density areas, and probably relates to the extent of use (i.e. age of the burrows and number of badgers using them) of the burrow system. The number of setts per badger territory is related positively to territory size. The similarity of sett densities between this low density population and high density populations, points to a minimum number of setts being required to maximize territory use, and to offer easily-available protection. The preservation and improvement of Mediterranean scrubland vegetation, as well as of large and old shrubs, are important for the future conservation of the badger in Mediterranean landscapes. In these areas, and given the impossibility of distinguishing main setts, the estimation of absolute densities in population surveys using main sett numbers should be avoided in favour of relative indices of abundance.

One of the hypotheses proposed to account for why badgers Meles meles are highly social in the U.K., the resource dispersion hypothesis, is that patchy resources are unpredictably dispersed in the environment and therefore must be shared, but that these patches are rich enough, when available, to support several badgers at any one time. Previous empiricists in our study site at Wytham Woods calculated that single patches could be rich enough to support 30 badgers in a night. The sustained increase in population density in Wytham Woods suggests that food was not limiting and territories were below capacity, and therefore that feeding competition was relatively low. Low feeding competition would predict an absence of dimorphism in trophic apparatus between the sexes. Contrary to this, significant sexual dimorphism was found, after removing effects resulting from body size allometry, in canine cross-section length, width (both P < 0.0001) and skull breadth (P < 0.001). The differences in canine dimensions were still significant when allometry of both body length and skull breadth are accounted for statistically (P < 0.0001). It is therefore suggested that feeding competition may not necessarily be low, which would have implications for understanding the costs of social behaviour. Alternative explanations involving sexual selection and phylogenetic inertia are discussed.

In lowland England, badgers Meles meles form social groups of up to 30 individuals. They share a main den (sett) and a core feeding range, but largely forage alone. Faeces are deposited in discrete hinterland and border ‘latrines’. Border latrines are shared with neighbouring groups. We demonstrate that there is a highly significant tendency for neighbouring groups to place a similar quantity of faeces at shared latrines. There are also significant tendencies to place more faeces in boundary latrines close to the sett, and for reduced separation of latrines close to the sett. We also demonstrate that badgers tend to defecate most frequently on the boundary closest to their current feeding site. These observations are consistent with the hypothesis that faeces at border latrines are used to promote range exclusion. We propose that faecal volume represents a reliable signal of the encounter likelihood and/or foraging pressure of badgers along a particular border. According to the ‘active territorial defence’ hypothesis, this indicates a stand-off position in terms of each group's resource holding potential by signalling encounter likelihood across the boundary. By the ‘passive range exclusion’ hypothesis, this border is an isopleth (equal contour) of resource depletion between groups, and crossing over such a contour deep into a neighbouring range reduces foraging efficiency. By either hypothesis, the matched faecal volume and sett proximity effects suggest a simple mechanism that is capable of allowing reliable information to be passed by individuals between adjacent sectors of neighbouring territories to deter intrusion. This is a ‘bottom–up’ process of inter-dependent, parallel, individual responses, which is capable of generating the emergent complexity of co-ordinated group ranges without central control.

Controlled studies with baits containing the biomarkers iophenoxic acid or tetracycline were carried out to measure bait uptake by free-living badgers. The presence of these biomarkers was determined in badger plasma and dentition. The biomarkers were then incorporated into baits to quantify bait uptake by badgers in the field. Seven captive badgers were orally dosed with iophenoxic acid, which was subsequently measured in serial plasma samples for 18 weeks. Subsequently, field studies using baits marked with iophenoxic acid were carried out at selected setts in two study areas. In other experiments, five cage-trapped badgers were orally dosed with tetracycline and released. These badgers were subsequently re-trapped and the presence of tetracycline measured in sections of canine teeth. Field trials were also carried out using baits marked with tetracycline in four separate study areas. Badgers dosed with iophenoxic acid had elevated plasma iodine in comparison to a pre-dose baseline level. The elevations in plasma iodine could be detected throughout the sampling period. Field experiments using iophenoxic acid showed that c. 80% of wild badgers had ingested the marked bait. In addition, all five badgers dosed with tetracycline had tetracycline deposits in their canine teeth. Between 20% and 77.8% of badgers trapped in the tetracycline field trials were positive for uptake of the tetracycline-marked bait. Variation in the percentage of badgers marked was attributed to several factors including seasonal timing of bait deployment. Our results indicated that iophenoxic acid and tetracycline were effective biomarkers of bait uptake by badgers.

Genetic diversity in four populations of the Eurasian badger Meles meles from Denmark was estimated by allozyme electrophoresis. Low genetic variability was found within populations as compared to the variability found in badger populations from other countries, whereas significant genetic differentiation was found between populations. The low genetic variability and the differentiation between populations is explained by the fragmentation of the Danish landscape, which reduces the effective population size of local populations and the gene flow between them. Low genetic variability found for Danish badgers also supports the hypothesis of a rapid recolonization following the last glaciation.

Spotlight transect surveys with distance sampling were used to estimate spring (pre-breeding) and autumn (post-production) fox Vulpes vulpes densities in three contrasting rural areas of Britain during 1995–97. This was the first attempt in Britain to measure and compare fox densities over large geographical areas (630–1460 km2). Mean post-production fox abundance was estimated to be 0.90/km2, 2.62/km2, and 0.59/km2 in mid-Wales, the east Midlands and East Anglia, falling to pre-breeding levels of 0.41/km2, 1.17/km2, and 0.16//km2 in spring. As relative measures of regional density, these estimates are strongly supported by independent indices of fox abundance, and by the simultaneous survey of two sympatric species, the badger Meles meles and brown hare Lepus europaeus, which demonstrate the absence of any terrain-related bias. Absolute abundance is less easy to verify, but estimates of spring density based on breeding earth censuses support the transect surveys. For two of the three regions, fox density was close to levels predicted by extrapolation on the basis of landscape, but in the third region (East Anglia), fox density was substantially below prediction. Thus, results failed to support a hypothesis that fox abundance can be predicted solely on the basis of landscape and its close correlates. Rather, they favoured a competing hypothesis that an independent factor determines fox abundance in some regions. A likely factor is culling by man.