Increasing frequency of bite wounds with increasing population density in Eurasian badgers, Meles meles

Eurasian badgers sometimes live in territorial, mixed-sex groups; the adaptive significance of this is not understood, but members generally interact amicably. None the less, badgers occasionally fight and inflict sometimes severe wounds on one another. Based on 498 badger life histories, from first emergence as a cub until death, documented during a 10-year trapping study at Wytham Woods, Oxfordshire, U.K., the patterns and rates of bite wounding and consequential scarring were examined. Male badgers received more wounds and more severe wounds than did females. Wounding rates for both sexes increased significantly with age, and there was evidence that heavier individuals received most wounds. No seasonal pattern in wounding rates was apparent. During the study, the badger population size increased three-fold and wounding rates, particularly in males, showed a density-dependent increase. The rate of bite wounding increased with group size, and this increase was more marked among males than among females. Among males, but not females, the rate of bite wounding also increased with the number of badgers living in adjoining territories.     

Distribution and population density of badgers Meles meles in Luxembourg

1. The distribution and density of Eurasian badgers Meles meles in Luxembourg was estimated by gathering information about the location of badger setts with a questionnaire survey, by visiting 708 setts in order to classify them as ‘main setts’ or ‘outliers’, and by estimating social group size by directly counting emerging badgers. 2. Badgers were found to be widely distributed in Luxembourg, with a minimum main sett density of 0.17 setts/km². Setts were sited preferentially in forest habitat. The mean minimum group size was 4.6 badgers. 3. The Luxembourg badger population was conservatively estimated to contain at least 2010 adult and young badgers (95% CI 1674–2347) in spring 2002, equivalent to a density of 0.78 adult and young badgers/km² (95% CI 0.65–0.91). This is moderate compared to most of continental Europe.     

Winter hibernation and body temperature fluctuation in the Japanese badger, Meles meles anakuma

This study examined seasonal changes in body weight, hibernation period, and body temperature of the Japanese badger (Meles meles anakuma) from 1997 to 2001. Adult badgers showed seasonal changes in body weight. Between mid-December and February, badger activity almost ceased, as the animals remained in their setts most of the time. Adult male badgers were solitary hibernators; adult females hibernated either alone or with their cubs and/or yearlings. The total hibernation period of Japanese badgers ranged from 42 to 80 days, with a mean length of 60.1 days. Japanese badgers did not always spend the winters in the same sett, although they seldom changed setts during hibernation. I equipped a male cub with an intraperitoneally implanted data logger to record its body temperature between November and April, while the cub hibernated with its mother. Over the winter, the body weight of the cub decreased from 5.3 kg to 3.6 kg, a weight loss of 32.1%, and its body temperature ranged from 32.0 to 39.8 degrees C. The mean monthly body temperature was 35.1 degrees C in December, 34.8 degrees C in January, 35.9 degrees C in February, 37.1 degrees C in March, and 37.4 degrees C in April, so the monthly decrease in body temperature of this cub was not great. The results indicate that during hibernation, when body temperature is low, there is likely considerable economy of energy and a reduced demand for adipose reserves.     

The role of setts in badger (Meles meles) group size, breeding success and status of TB (Mycobacterium bovis)

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.     

Density dependence in a fluctuating wild reindeer herd; maternal vs. offspring effects

Summary The Hardangervidda wild reindeer herd in Norway is the largest in Western Europe. It has fluctuated between 7000 and 32000 animals during the last 35 years. Four density-dependent effects were found: 1. A food limitation effect due to a shift in diet after overgrazing lichen on the winter range. This led to increased tooth wear and lowered body size and fat reserves. 2. A significant correlation between population density and juvenile winter survival rate. No effect on adult female survival rate was found. 3. A cohort effect. After population increase and overgrazing, recruitment was reduced by 30% and remained so after population reduction. Birth weights had increased by 30% 5 years after population reduction and the mean calving time was earlier. As a result, after population reduction weights of newborns were 40% greater at a comparable date. Neonatal survival rate was related to maternal condition during the last part of gestation which coincides with the peak winter snow accumulation. The slow increase in adult dressed body weights (DBW) after population reduction is due to the combined effects of increased tooth wear when winter range was limiting and to the cohort-generation time, so that an improvement in neonatal survival and size was first expressed in subsequent offspring cohorts. 4. An inter-generation effect. During 30 years of resource limitation, DBW decreased by 23%, birth rate was unchanged after the first peak, while fecundity increased by 15%, suggesting increased reproductive effort per unit body weight. Natural selection for increased reproductive effort by smaller females when food was limiting was suggested. Some size-effect due to hunters selecting the largest adult phenotypes was possible but not the main cause. These results do not support some earlier hypotheses about the effects of population density on size at maturity in ungulates.     

Dynamics of a harvested moose population in a variable environment

1. Population size, calves per female, female mean age and adult sex ratio of a moose ( Alces alces ) population in Vefsn, northern Norway were reconstructed from 1967 to 1993 using cohort analysis and catch-at-age data from 96% (6752) of all individuals harvested.
2. The dynamics of the population were influenced mainly by density-dependent harvesting, stochastic variation in climate and intrinsic variation in the age-structure of the female segment of the population.
3. A time delay in the assignment of hunting permits in relation to population size increased fluctuations in population size.
4. Selective harvesting of calves and yearlings increased the mean age of adult females in the population, and, because fecundity in moose is strongly age-specific, the number of calves per female concordantly increased. However, after years with high recruitment, the adult mean age decreased as large cohorts entered the adult age-groups. This age-structure effect generated cycles in the rate of recruitment to the population and fluctuations introduced time-lags in the population dynamics.
5. An inverse relationship between recruitment rate and population density, mediated by a density-dependent decrease in female body condition, could potentially have constituted a regulatory mechanism in the dynamics of the population, but this effect was counteracted by a density-dependent increase in the mean age of adult females.
6. Stochastic variation in winter snow depth and summer temperature had delayed effects on recruitment rate and in turn population growth rate, apparently through effects on female body condition before conception.     

Density-Dependent Fertility Selection in Experimental Populations of DROSOPHILA MELANOGASTER

The effects of larval density on components of fertility fitness were investigated with two mutant lines of Drosophila melanogaster. The differences in adult body weight, wing length, larval survivorship and development time verified that flies reared at high density were resource limited. Experimental results indicate that: (1) relative fecundities of both sexes show density-dependent effects, (2) there is a strong density effect on male and female mating success, and (3) in general, there is a reduction in fecundity differences between genotypes at high density. These results imply that it may be important to consider fertility in models of density-dependent natural selection.     

In situ adaptive response to climate and habitat quality variation: spatial and temporal variation in European badger (Meles meles) body weight

Variation in climatic and habitat conditions can affect populations through a variety of mechanisms, and these relationships can act at different temporal and spatial scales. Using post‐mortem badger body weight records from 15 878 individuals captured across the Republic of Ireland (7224 setts across ca. 15 000 km²; 2009–2012), we employed a hierarchical multilevel mixed model to evaluate the effects of climate (rainfall and temperature) and habitat quality (landscape suitability), while controlling for local abundance (unique badgers caught/sett/year). Body weight was affected strongly by temperature across a number of temporal scales (preceding month or season), with badgers being heavier if preceding temperatures (particularly during winter/spring) were warmer than the long‐term seasonal mean. There was less support for rainfall across different temporal scales, although badgers did exhibit heavier weights when greater rainfall occurred one or 2 months prior to capture. Badgers were also heavier in areas with higher landscape habitat quality, modulated by the number of individuals captured per sett, consistent with density‐dependent effects reducing weights. Overall, the mean badger body weight of culled individuals rose during the study period (2009–2012), more so for males than for females. With predicted increases in temperature, and rainfall, augmented by ongoing agricultural land conversion in this region, we project heavier individual badger body weights in the future. Increased body weight has been associated with higher fecundity, recruitment and survival rates in badgers, due to improved food availability and energetic budgets. We thus predict that climate change could increase the badger population across the Republic of Ireland. Nevertheless, we emphasize that, locally, populations could still be vulnerable to extreme weather variability coupled with detrimental agricultural practice, including population management.     

DENSITY-DEPENDENT NATURAL SELECTION IN DROSOPHILA: EVOLUTION OF GROWTH RATE AND BODY SIZE

Drosophila melanogaster populations subjected to extreme larval crowding (CU lines) in our laboratory have evolved higher larval feeding rates than their corresponding controls (UU lines). It has been suggested that this genetically based behavior may involve an energetic cost, which precludes natural selection in a density-regulated population to simultaneously maximize food acquisition and food conversion into biomass. If true, this stands against some basic predictions of the general theory of density-dependent natural selection. Here we investigate the evolutionary consequences of density-dependent natural selection on growth rate and body size in D. melanogaster. The CU populations showed a higher growth rate during the postcritical period of larval life than UU populations, but the sustained differences in weight did not translate into the adult stage. The simplest explanation for these findings (that natural selection in a crowded larval environment favors a faster food acquisition for the individual to attain the same final body size in a shorter period of time) was tested and rejected by looking at the larva-to-adult development times. Larvae of CU populations starved for different periods of time develop into comparatively smaller adults, suggesting that food seeking behavior in a food depleted environment carries a higher cost to these larvae than to their UU counterparts. The results have important implications for understanding the evolution of body size in natural populations of Drosophila, and stand against some widespread beliefs that body size may represent a compromise between the conflicting effects of genetic variation in larval and adult performance.     

The distribution of Eurasian badger, Meles meles, setts in a high-density area: field observations contradict the sett dispersion hypothesis

Are setts significant determinants of badger socio‐spatial organisation, and do suitable sett sites represent a limited resource, potentially affecting badger distributions? The factors determining diurnal resting den, or sett, location and selection by Eurasian badgers Meles meles L. were investigated in Wytham Woods, Oxfordshire. 279 sett sites were located. The habitat parameters that were associated with the siting of these setts were analysed and associations were sought between sett location and character and the body condition and body weight of resident badgers Habitat characteristics in the vicinity of setts were significantly different from randomly selected points. Badgers preferentially selected sites with sandy, well‐drained soils, situated on NW‐facing, convex and moderately inclined slopes at moderate altitude. There was no evidence that sett morphology (number of entrances, sett area, number of hinterland latrines) was affected by the surrounding sett site habitat characteristics. Mean body weight was significantly higher for badgers occupying territories with setts in sandy soils, situated on NW‐facing slopes, than in territories with less optimal sett characteristics. Contrary to the hypothesis that the availability of sett sites was limiting, and therefore that sett dispersion dictates the spatial and social organisation of their populations, the badgers were clearly able to excavate new setts. On our measures, these new setts were not inferior to old established ones, despite occupying subsequently exploited sites; the badgers utilising these new setts had neither lighter body weights nor poorer body condition scores. During the period of our study badgers have manifestly been able to dig numerous new setts; as satisfactory sites still remain available, this indicates that suitable sett sites have not yet become a limiting resource. There was no relationship between sett age and the characteristics of the site in which it was dug, as suitable sites were not limiting. Significantly, population expansion during the decade 1987–1997 was not constrained by lack of setts, rather the main proliferation in setts occurred after the population size had peaked in 1996. Some implications for the management and conservation of the Eurasian badger are considered.     

Sexual dimorphism in the skull of minks Mustela vison, badgers Meles meles and otters Lutra lutra

Multiple-group principal component analysis and discriminant analysis were used to investigate the morphological differences between adult skulls of male and female minks, badgers and otters from Norway. The first principal component axis, calculated from the variance-covariance matrix of log-transformed data, was interpreted as a growth-free size axis in all three species, while the other components were interpreted as representing shape. Having largely separated size and shape variation, these two aspects of sexual dimorphism could be studied. The standardized component scores were subjected to an analysis of variance and discriminant analyses were performed on size-in and size-out data. Sexual dimorphism was disclosed on eight of the 12 components in minks and on seven of the 12 components in badgers and otters. In mink the multivariate differences were more due to size than to shape, whereas in badgers and otters most of the multivariate differences were due to shape, but the differences in size were also significant. The shape dimorphism was shown to be functionally related to jaw and neck muscles. The results were discussed in relation to recent theories to explain the evolutionary significance of sexual dimorphism in body size of mustelids. It was concluded that these theories do not fully explain the dimorphism found in the skulls of the moderately dimorphic badger and otter.     

Density- and size-dependent mortality of a settling coral-reef damselfish (<Emphasis Type="Italic">Pomacentrus moluccensis</Emphasis> Bleeker)

Density-dependent mortality may regulate many populations, but due to an offshore larval phase in benthic marine organisms, it is often difficult to quantify the effects of mortality of arriving individuals. We added approximately 600 recruit-sized individuals onto coral reef that parallels patterns in naturally settling fish. Strong, positive density-dependent mortality occurred 3 days, 1–2 weeks, and 4 months after release. Since our study species was patchily distributed, we estimated both mean group size and overall density in a transect. Mortality was more strongly related to mean group size than overall density in a transect, indicating that recruit patchiness was important. Cohesive groups may suffer higher mortality than those spread over larger areas, even if overall density of the latter is greater. Aggregative responses of predators may occur in response to larger groups, so may have contributed to positive density-dependent mortality. Increased conspicuousness to predators and congeneric aggression are additional factors that may vary positively with group size. Tagging of recruits showed migration within but not between transects, so persistence was tantamount to survival. Standard otolith back-calculation techniques employed to reconstruct original size of tagged recruits that persisted 4 months after additions indicated that mortality was also size-dependent. Size-dependent mortality was apparent at the site with the highest mortality but not at the site with the lowest mortality, resulting in different mean body sizes of recruits between sites. Size-dependent mortality may influence estimation of growth and lead to onset of size-based maturity in these fish. Strong, positive density-dependent mortality may regulate recruitment, and if coupled with size-dependent mortality, may increase maturity rate, adding to reproductive schedules of those that survive.     

Environmental networks,compensating life histories and habitat selection by white-footed mice

Summary Analysis of 6 years' data on a population of free-living white-footed mice documents both phenotypic and environmental control of litter size. Litter size was positively correlated with maternal body size. Maternal size depended upon both seasonal and annual variation. Paradoxically, the proportion of small versus large litters varied among habitats independently of the effects of body size. The result is an influence of habitat on life history that yields patterns of reproduction and survival opposite to the predictions of demographic theory. The habitat producing the largest litters had a relatively high ratio of adult/juvenile survival. Litter size was small in the habitat where the adult/juvenile survival ratio was smallest. All of these anomalous patterns can be explained through density-dependent habitat selection by female white-footed mice. Life-history studies that ignore habitat and habitat selection may find spurious correlations among traits that result in serious misinterpretations about life history and its evolution.     

Life-history parameters of a wild group of West African patas monkeys (Erythrocebus patas patas)

Based on long-term, although intermittent, observations (2 years 4 months of 14 years), we present data on birth seasonality, age at first birth, interbirth intervals, mortality rates, age at first emigration, and population change of a wild population of West African patas monkeys (Etythrocebus patas patas) in northern Cameroon. Birth season was from the end of December until the middle of February, corresponding to the mid-dry season. In spite of large body size, the patas females had the earliest age at first birth (36.5 monthsold) and the shortest interbirth intervals (12 months) compared to the closely related wild forest guenons. Age at first emigration of the males was considered to occur between 2.5 and 4.5 years. The group size of the focal group drastically decreased between 1984 and 1987, and steadily increased until 1994, then decreased again in 1997. The neighboring group also showed a similar trend in group size. The population decreases were likely to be caused by drought over 3 years. Annual crude adult mortality rate was 4% during population increase periods (PIP) between 1987 and 1994. It rose to 22% during all the periods (AP), including drought over 3 years. Despite their smaller body size, the rate of the wild forest guenons (Cercopithecus mitis) (4%) was the same and much lower than those of the patas during PIP and AP, respectively. The annual average juvenile mortality rate was 13% during PIP and it also rose to 37% during AP. That of wild forest guenons (C. ascanius) (10–12%) was a little lower and much lower than those of the patas during PIP and AP, respectively. These findings were consistent with Charnov's theoretical model of mammalian life-history evolution in that patas with high adult and juvenile mortality showed early and frequent reproduction in spite of large body size. Charnov also considered high adult mortality as a selective force and high juvenile mortality as a density-dependent consequence of high fecundity. Our results support the former but not the latter research findings.     

Sex-dependent effects of sibling cannibalism on life history traits of the ladybird beetle Harmonia axyridis (Coleoptera: Coccinellidae)

To investigate the sex-dependent effects of sibling cannibalism on variations in life history traits, I analysed body size, weight and instar interval in relation to the occurrence of sibling cannibalism in the ladybird beetle Harmonia axyridis. Sibling cannibalism at the time of hatching significantly affected the body size and weight of adults. There was a 2.32% and 1.05% increase in the body size of males and females, respectively, and a 3.55% increase and a 2.30% decrease in their respective body weights. Sibling cannibalism also significantly shortened the total and larval instar intervals, by 4.24% in males and by 1.22% in females, mainly due to shortening of the first instar. These results suggest that the effects of sibling cannibalism on life history traits are sex-differentiated and are greater in males than in females. A simulation of aphid density indicated that shortening the instar interval affected larval survival; the aphid density when the larvae completed development was 39.71% and 10.52% larger for cannibalistic males and females, respectively, than for non-cannibals. These results suggest that sibling cannibalism promotes more rapid development and larger adult size, although the effect was more pronounced in males than in females. Faster development may be adaptive for resource tracking, and the large adult size may increase fecundity in females and mating success in males through female mate choice, both resulting in an increase in the fitness of cannibals.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 76 , 349–360.     

Annual and circadian activity patterns of badgers (Meles meles) in Białowieża Primeval Forest (eastern Poland) compared with other Palaearctic populations

Aim The annual and circadian rhythms and duration of activity of Eurasian badger Meles meles (Linnaeus 1758) were studied in a low‐density population inhabiting the primeval woodland in the European temperate zone. Results were compared with available data from the literature on seasonal changes in body mass and winter inactivity of badgers from across the Palaearctic region. Location Field work was carried out in Bia?owie?a Primeval Forest, eastern Poland. Biogeographical variation was reviewed based on twenty‐three localities in the Palaearctic region (from Western Europe to Central Siberia). Methods Thirteen badgers were radio‐collared in 1997–2001. Their circadian activity was sampled by 24‐h sessions of continuous radio‐tracking with location taken at 15‐min intervals. Annual activity was studied by radio‐tracking and inspections of setts. Earthworm (badgers’ main food) biomass was estimated in four types of habitats throughout the year. Results Badgers were nocturnal with one long bout of activity. Their rhythms of diel activity differed between spring and autumn, and between adult and subadult individuals. On average, badgers emerged from setts at 19:00 hours and returned to them at 03:42 hours. The highest level of activity was recorded between 20:00 and 03:00 hours. Duration of daily activity was, on average, 8.2 h day^?1, but varied significantly between seasons. The seasonal changes were inversely related to the abundance of earthworms. Duration of activity also depended on daily temperature, especially in the cold season. In winter, badgers stayed inactive for an average of 96 days per year. In autumn, they built fat reserves and their body mass nearly doubled compared with the spring values. The literature review on annual cycle of activity and body mass changes in Eurasian badgers showed that fat storage and duration of winter sleep strongly depended on climate (best approximated by January mean temperature). In regions with warm climates, badgers were active year round and their body mass changed only slightly, while in regions with severe winters badgers increased their body mass twofold from spring to autumn, and stayed inactive for as long as 6 months per year. Main conclusion We propose that, in the temperate and boreal zones of the Palaearctic region, the ultimate determinant of biogeographical variation in badgers’ annual activity is the winter shortage of earthworms, which are the main component of badger diet.     

BODY SIZE DECLINES DESPITE POSITIVE DIRECTIONAL SELECTION ON HERITABLE SIZE TRAITS IN A BARNACLE GOOSE POPULATION

Analyses of more than 2000 marked barnacle geese (Branta leucopsis) in the largest Baltic colony, Sweden, showed that structurally large females generally produced larger clutches and larger eggs, hatched their broods earlier in the season, and produced more and heavier young than smaller females. In males, the corresponding relationships between reproductive parameters and structural body size were weaker or nonsignificant. Because structural body size traits have previously been found to be significantly heritable and positively genetically correlated, an increase in mean structural body size of individuals as a response to selection might have been expected. By contrast, we found that the mean adult head length and mean adult tarsus length decreased significantly in the largest colony by approximately 0.7 and 0.5 standard deviations, respectively, in both males and females during the 13-year study period. Environmental factors, such as the amount of rain in different years, were found to affect the availability of high-quality food for growing geese. As a consequence of this temporal variability in the availability of high-quality food, the mean adult structural body size of different cohorts differed by up to 1.3 standard deviations. Comparisons of mean body size of cohorts born in different colonies suggest that the most likely explanation for the body-size decline in the main study colony is that a density-dependent process, which mainly was in effect during the very early phase of colony growth, negatively affected juvenile growth and final size. We conclude that large environmental effects on growth and final structural body size easily can mask microevolutionary responses to selection. Analyses of environmental causes underlying temporal and spatial body size variation should always be considered in the reconstruction and prediction of evolutionary changes in natural populations.     

Evaluating seasonal bait delivery to badgers using rhodamine B

In the UK and Ireland, research on the control of bovine tuberculosis in badgers includes the development of a palatable bait for oral delivery of a vaccine and a means of its deployment in the field. In the present study, we carried out field deployment of bait according to the established method of bait marking in early spring and early summer to compare the effects of seasonality on bait uptake rates. All baits contained rhodamine B (RhB) which was subsequently detected in the hair and whiskers of captured badgers. During the 8 days of bait feeding at 14 badger setts, 99% of baits deployed in spring, and 100% of those deployed in summer were removed. The presence of RhB in captured badgers indicated high rates of uptake amongst adult badgers in spring (93%) and summer (98%). Only cubs captured in summer showed evidence of having taken bait (91%). Between 67% and 100% of each social group was estimated to have taken bait. The detection of RhB in 96% of badgers captured at outlier setts, where bait was not fed, suggested that deployment at main setts alone may be sufficient to target a relatively high proportion of the badger population. The number of baits deployed per marked badger suggested that a similar level of uptake might be achievable using fewer baits. The results clearly demonstrate the potential value of the bait-marking methodology for delivering vaccine baits to badgers during spring and summer, but that deployment in early summer is necessary to target cubs.     

Density-dependent processes in the life history of fishes: evidence from laboratory populations of zebrafish Danio rerio

Population regulation is fundamental to the long-term persistence of populations and their responses to harvesting, habitat modification, and exposure to toxic chemicals. In fish and other organisms with complex life histories, regulation may involve density dependence in different life-stages and vital rates. We studied density dependence in body growth and mortality through the life-cycle of laboratory populations of zebrafish Danio rerio. When feed input was held constant at population-level (leading to resource limitation), body growth was strongly density-dependent in the late juvenile and adult phases of the life-cycle. Density dependence in mortality was strong during the early juvenile phase but declined thereafter and virtually ceased prior to maturation. Provision of feed in proportion to individual requirements (easing resource limitation) removed density dependence in growth and substantially reduced density dependence in mortality, thus indicating that 'bottom-up' effects act on growth as well as mortality, but most strongly on growth. Both growth and mortality played an important role in population regulation, with density-dependent growth having the greater impact on population biomass while mortality had the greatest impact on numbers. We demonstrate a clear ontogenic pattern of change in density-dependent processes within populations of a very small (maximum length 5 mm) fish, maintained in constant homogeneous laboratory conditions. The patterns are consistent with those distilled from studies on wild fish populations, indicating the presence of broad ontogenic patterns in density-dependent processes that are invariant to maximum body size and hold in homogeneous laboratory, as well as complex natural environments.     

To breed or not to breed: an analysis of the social and density-dependent constraints on the fecundity of female badgers (Meles meles).

Data from post-mortem examinations, population density estimates and long term capture-mark-recapture studies have been combined to look at the pattern of reproductive behaviour and the social factors leading to reproductive failure in badgers in Britain. The results are used to evaluate whether the hypothesis that the defence of oestrous females (as opposed to defence of food resources) best explains territorial behaviour and the social organization of badgers. Badgers in Britain have two peaks of reproductive activity, one immediately post partum and one in the summer/autumn. These coincide with two peaks of ovulation, and in the late winter/spring there is a steep rise in the number of sows carrying blastocysts, to reach an asymptote in June for yearling sows and April in older sows. Measured by their contribution to overall productivity, winter/spring matings were much more important than summer/autumn matings, contributing 65% of total autumn blastocysts in yearling sows and 71% of autumn blastocysts in older sows. The relative importance of the two mating periods is reflected in the seasonal pattern of bite wounding in adult male badgers; minor bite wounding in January-March was 2.3 times as frequent as in August-October, and moderate-extensive bite wounding was 3.1 times more frequent. In the populations studied, pre- and post-natal losses were high, with reproductive failure occurring at all stages of the breeding cycle, so that less than 30% of potential productivity was achieved. Indeed 22% of sows failed to develop blastocysts; these had a lower body mass, less body fat, larger adrenal glands, poorer health and higher bite wound scores than sows with blastocysts. Only 44% of adult sows implanted their blastocysts and proceeded to the end of pregnancy. However, it was less easy to identify features characteristic of sows that did or did not go on to implant their blastocysts. Finally, 35% of sows that produced cubs ceased lactation early, and this loss of entire litters was thought to be due to infanticide by dominant sows. The presence of annexe setts correlates with increased productivity in younger sows, and this is thought to be because annexe setts enable younger sows and their cubs to avoid the aggression of older, more dominant sows. Living in large social groups has no net reproductive gain for adult males or females, and there was a decline in productivity (per adult) with increasing group size.(ABSTRACT TRUNCATED AT 400 WORDS)