Resource Dispersion Research Articles

Heterogeneity, patchiness and correlation of resources

In this paper, I argue that many ecological ideas that are typically expressed in terms of ‘patches’ of habitat can be framed more generally in terms of spatial correlation of resource availability. This avoids practical difficulties in the definition of a ‘patch’ in a given study. The idea is illustrated by reference to some existing models of territoriality, and by revisiting a model for the resource dispersion hypothesis. As an example, I show how this perspective resolves one of the difficulties of interpretation in a study of spatial organization in urban foxes.

Spatial organization and behaviour of badgers (Meles meles) in a moderate-density population

Badgers are carnivores that show considerable variation in their social and spatial organization. At the westernmost part of their range, in Britain and Ireland, variation in spatial organization appears to be determined by the availability of resources. However, the majority of studies has focussed at one end of the social/spatial spectrum, where population densities are high and adjacent territories are contiguous and non-overlapping. To examine whether the same limiting factors appear to apply across a wider range of badger densities, we established a study site in a predominantly coniferous habitat within an upland area of northeast England, where population densities were predicted to be low. Seasonal home ranges of individual badgers were largest in autumn, followed by summer and spring, then winter. This pattern is reflective of the likely seasonal changes in food availability within the area, as opposed to being related to breeding patterns. There were also significant correlations between territory size and the number of grassland patches (positive) and the proportion of grassland (negative), which are consistent with predictions from the Resource Dispersion Hypothesis. Although badgers at the site were living at low to moderate densities relative to many other studied populations in Britain, they showed patterns of spatial organization that were close to those of high-density populations. The nature of the relationship between resource availability and abundance patterns is likely to have important consequences for the conservation and management of badgers and other species that show flexible spatial organization.

Soil C and N pools in patchy shrublands of the Negev and Chihuahuan Deserts

Patchy distribution of vegetation within semi-arid shrublands is normally mirrored in the soil beneath perennial shrubs (macrophytic patches), compared to inter-shrub areas (microphytic patches). To determine impacts of (1) litterfall inputs within vegetation patches and (2) rainfall distribution on soil C and N, we investigated soil C and N pools and associated soil properties in two semi-arid shrublands, in the Negev Desert of Israel (Lehavim), which receives >90% of annual rainfall during winter and in the Chihuahuan Desert, USA (FHMR) that experiences a bimodal (Summer–Winter) annual rainfall pattern. We also evaluated grazing effects on soil C and N pools at Lehavim. More distinct differences in soil properties existed between patch types at the Negev site, where the soils contained higher soil organic C and N, amino acids and sugars, asparaginase activity and plant-available N than those at FHMR. Soil organic C (0–5 cm) in macrophytic patches was 39 g/kg at Lehavim and 13 g/kg at FHMR, and asparaginase activity was as high as 70 μg N/g 2 h in macrophytic patches at Lehavim, two times higher than at FHMR. The soil (0–5 cm) δ 13C was −15 to −18‰ at Lehavim and −18 to −19‰ at FHMR, with significantly lower δ 13C in macrophytic patches at both sites. The δ 13C suggested that considerable macrophytic patch soil C was derived from cyanobacteria at Lehavim and C4 grasses at FHMR. Plant litter δ 15N was 0.9‰ at Lehavim and 0.6‰ at FHMR, suggesting that much plant N was derived from N fixation. Concentrations of inorganic soil N (NH 4 ++NO 3 −) were up to 37 mg N/kg at Lehavim and <9 mg N/kg at FHMR. Grazing at Lehavim resulted in lower soil CH, AA, and AS. We conclude that differences between the sites are due largely to (i) higher amounts of litterfall C and N inputs within macrophytic patches at Lehavim and (ii) the different precipitation patterns, with summer precipitation at FHMR promoting increased organic matter mineralization compared to Lehavim, which experiences Winter precipitation only. Furthermore, greater differences in soil properties between patch types at Lehavim compared to FHMR can likely be attributed to the increasing importance of physical processes of resource dispersion at the more humid site in Arizona.

The social integration of European badger (Meles meles) cubs into their natal group

Three main reasons have been suggested to explain the evolution of stable social groups in mammals: cooperation, resource dispersion, and natal philopatry. Here, we investigate the driving forces behind the social integration of badger Meles meles cubs into their natal group as a model for those species, where group-living has been attributed to ecological constraints. Between March 1995 and June 1996, we observed the cub/adult interactions of 9 litters in 2 badger social groups in Wytham Woods, Oxfordshire, from the time of their first emergence to full independence using remote controlled IR-video surveillance equipment. Our results show that with increasing age, cubs emerge earlier from the sett, interact with an increasing number of adults, and initiate a greater proportion of social interactions. Young cubs exhibit a specific behaviour (here termed 'scent-theft') to mark themselves with the subcaudal gland secretion of adult group-members, shown to carry group-specific information. In contrast to other social carnivores, badger cubs are not the focus of attention from adult group-members, but, supporting our hypothesis, their social integration into the natal group is gradual and cub-driven.

Resource dispersion and badger population density in Mediterranean woodlands: is food, water or geology the limiting factor?

Eurasian badgers, Meles meles, in Mediterranean cork‐oak woodlands live in small groups within territories that embrace a mosaic of habitats where several setts (dens) are scattered. Assuming that their population density was related to home range sizes and that this in turn was influenced by food and water availability and the existence of substrate suitable for sett construction, we explored the relationship between these parameters. Two biotopes were predominantly important in providing food security to badgers in the ‘Grândola’ mountain study area: olive groves and orchards or vegetable gardens. Analysis of the mean total area of these two habitats in the ranges of radio‐tracked badgers permitted us to extrapolate to an estimate that the 66 km2 encompassed eleven areas with the capacity to support badger groups each composed by 6–8 individuals. Since only three groups populated the area we concluded that food availability was not limiting badger density. Sites with surface water in summer (the dry season) seem sufficient to support more badger groups than existed, leading us to believe that this factor was also not limiting badger density. Simultaneously, using a logistic regression model and the biophysical characteristics of sett sites as explanatory variables, four predictor variables determined sett location: the existence of a geological fault/discontinuity, ridges, valleys and the distance to abandoned farm houses, of which the former had the higher odds ratio, being thus the best sett location predictor. Indeed, 56% of the areas predicted with &gt;80% confidence to contain a badger sett were encompassed within a known home range. Therefore, our results suggest that, in Mediterranean cork oak woodlands in SW Portugal, the main factor limiting badger's density is the availability of suitable sites for setts. However, in areas where suitable sites for burrows existed, but food patches were absent, badgers were not found. This could indicate that the presence of both factors was necessary for badgers, although in this area sites suitable for digging setts appeared to be the primary limiting factor.

Spatial organization of reproductive Arctic foxes Alopex lagopus: responses to changes in spatial and temporal availability of prey

Summary 1. Home range size, spatial organization and territoriality of reproductive Arctic foxes were studied during the summer. The influence of spatial distribution and availability of the main prey was investigated in order to evaluate whether the spatial organization of Arctic foxes was coherent with key predictions of the resource dispersion hypotheses (RDH). The RDH includes the spatial characteristics of resource abundance, while there is also growing attention to the importance of the temporal characteristics of resource abundance. Hence the role of temporal and spatio-temporal predictability of prey explaining carnivore spatial organization was also investigated in this study. 2. The study was conducted on Svalbard; a simple High-Arctic terrestrial ecosystem which allowed unique estimates of prey abundance. The main prey of the Arctic fox (Svalbard reindeer Rangifer tarandus platyrhynchus , seabirds Alcidae and Procellariidae and geese Anseridae ) was surveyed systematically. These surveys revealed highly contrasting patterns in prey abundance within the terrestrial ecosystem. 3. Arctic fox summer home ranges varied in size (4‐60 km 2 ), as well as in overlap (17‐ 76%). The diverse spatial organization covaried with spatial and temporal patterns in prey abundance. Small home ranges (10 ± 5·6 km 2 ) with large overlap (76 ± 19·6%) were characteristic for coastal areas where prey was concentrated in small patches and predictable both in space and time. Medium home ranges (23 ± 4·2 km 2 ) and overlap (50 ± 6·6%) occurred inland where prey was clumped in larger patches and less predictable. Large home ranges (52 ± 8·4 km 2 ) with little overlap (17 ± 3·5%) occurred inland where prey was widely scattered and unpredictable. 4. Spatial dispersion and richness of prey resources explained most of the variation in Arctic fox spatial organization. The RDH framework could be used to explain the presence of relaxed territoriality found in this study. We suggest that the observed absence of more permanent social groups is due to the extremely severe winter conditions which force juvenile individuals to disperse from the natal area during the first winter. 5. Predictability of resources was an additional significant factor affecting both home-range size and overlap. Resource predictability captures the degree to which an animal can depend on its environment to offer suitable and secure living conditions over time. 6. This study emphasize the need to incorporate both spatial and temporal characteristics of resource distribution in order to fully understand the diversity of spatial arrangements among carnivores.

Peace in ground beetle larvae: non-aggressive outcome in Chlaenius spp. larvae interactions

Cannibalism reduces the number of competitors and provides high-quality food, but it may have costs related to the risk of injury, disease/parasite transmission and reduction of inclusive fitness. Carabid larvae are usually very aggressive, with very low tolerance of conspecifics. Thus cannibalism is common. We investigated aggressive and cannibalistic behaviour in the larvae of eight ground beetle species, especially Chlaenius velutinus and Chlaenius spoliatus whose larvae have long articulated cerci. Chlaenius species live in dense populations with frequent intra-specific encounters, whereas encounters are rare in the other species. Dyads of conspecific larvae of the eight ground beetles species were tested for aggressive and cannibalistic behaviour. Unlike the other six species, larvae of the two Chlaenius species avoid cannibalism, possibly as a consequence of a behavioural display involving cerci interactions. This display was never recorded in conspecific larval interactions of the other species. Instead, cannibalism consistently occurred (20 to 50%) following aggressive interactions (1.2 to 2.6 attacks/event). The non-aggressive outcome in Chlaenius larval interactions contrasts with the high aggressiveness (35 to 85% of trials) shown by the other species. This suggests the presence of an inhibitory mechanism in the Chlaenius species. The cerci interaction probably inhibits cannibalism via intra-specific recognition; this behaviour may have evolved under the pressure of ecological factors (resource abundance and dispersion, larvae density, frequency of encounters). In Chlaenius spp. ecological constraints may have led to an inconvenient costs/benefits trade-off, while in other species they did not exert negative pressure on the occurrence of cannibalism.

Spatial structure and land-cover use in a low-density Mediterranean population of Eurasian badgers

Eurasian badgers, Meles meles (L., 1758), have an extensive geographic range throughout which their social organization varies. Their capacity for intraspecific variation can now best be understood by studying them in landscapes that differ from the lush, lowland farmland where their tendency to form large groups has been most intensively investigated. Badgers in cork oak (Quercus suber L.) woodland are thus a priority for study, as this Mediterranean landscape provides an extreme contrast to those studied elsewhere. In this habitat in Portugal, we found 0.36–0.48 badgers/km2, one of the lowest population densities recorded in Western Europe. Here, individuals used seasonally stable home ranges that averaged 4.46 km2and that were occupied by 3–4 adults plus 3–4 cubs of the year. In this landscape, badgers selectively used cork oak woodland with understory and riparian vegetation. As predicted by the resource dispersion hypothesis, home-range size was positively correlated with food-patch dispersion. In southwestern Portugal, badgers depend upon an environmental mosaic such as olive groves and orchards and vegetable gardens for food and cork oak woodlands for shelter and protection.

REPRODUCTIVE BEHAVIOR IN FEMALE IBERIAN RED DEER: EFFECTS OF AGGREGATION AND DISPERSION OF FOOD

Resource dispersion influences mammalian mating systems by affecting space use by females and in turn the strategies employed by males. Other elements related to mating interactions, however, also may affect female decisions, and it usually becomes difficult to discriminate between them. Here we present the results of experimental food supplementation during rut in the red deer (Cervus elaphus hispanicus). We provided food at 2 levels of spatial dispersion in order to test whether changes in the distribution of food within a short period of time affect spatial behavior of females or other features of the mating system. Food clumping produced an increase in local density of females using an area and in the size of female groups. It also produced an increase in number of adult males, male–male interactions, and male harassment toward females. Despite the overall rate of harassment being higher with food clumping, females received a lower per capita rate of harassment because they gathered into much larger harems. Variance in harem size increased with higher levels of food clumping. Our data show that females were highly sensitive to food distribution when joining harems, which stresses the relative importance of direct benefits (food and sexual harassment avoidance) in molding the conditions under which selection operates during rut in Iberian red deer.

Effect of a landfill on the home range and group size of coyotes (Canis latrans) in a tropical deciduous forest

AbstractThe effect of an open landfill and the seasonality of a tropical deciduous forest in Jalisco, Mexico, was tested on the home range and group size of coyotes Canis latrans under the Resource Dispersion Hypothesis (RDH), which proposes that in social carnivores dispersion of patches of limited resources determines home‐range size, whereas independently, abundance of resources affects group size. The predictions in this study were that coyotes using the landfill, where food is available all year due to the continuous arrival of food wastes that are concentrated in a single patch, would have smaller, seasonally constant home ranges than coyotes living outside, where food is distributed in several patches. In this area, coyotes would increase their home ranges during the dry season due to seasonal changes in resource availability. Also, a larger coyote group size should exist in the landfill, where food abundance is greater. Home‐range size and group size of coyotes living in and outside the landfill were estimated by radio‐tracking. Home ranges of coyotes in the landfill varied from 0.9 to 9.5 km2, whereas home‐range sizes of coyotes outside the landfill varied from 10.9 to 43.7 km2. Seasonality had no effect on the home‐range sizes. We identified a group of four adult coyotes in the landfill and no group formation in coyotes outside. These results support the predictions about home‐range and group size of coyotes in relation to landfill presence, and indicate that under the circumstances of our study, coyotes follow the postulates proposed by the RDH.

The Causes of Resource Monopolization: Interaction Between Resource Dispersion and Mode of Competition

AbstractThe degree of monopolization of resources is thought to be higher in groups that compete by interference than by exploitation. However, the monopolization of resources will presumably depend on (1) whether the dispersion of resources is economically defendable, and (2) whether some competitors have the ability to defend these resource distributions and hence capitalize on this potential. We tested for an interaction between the effects of temporal resource dispersion and aggressiveness on the degree of resource monopolization in a foraging system. Two species of fish differing markedly in aggressiveness (high: convict cichlids, Archocentrus nigrofasciatus; low: goldfish, Carrasius auratus) were allowed to compete intra‐specifically in groups of four for food that was either potentially defendable (arrived asynchronously) or not (arrived synchronously). As predicted, the monopolization of food, measured as the coefficient of variation of food eaten within groups, was significantly higher in the defendable than in the undefendable treatment for convict cichlids but not for goldfish. However, the monopolization of food was higher in the non‐aggressive goldfish than in the aggressive convict cichlids. Future studies should quantify and compare the monopolization in species that compete primarily via scramble competition to those that use primarily resource defence.

Movement patterns and home range of Cape clawless otters (Aonyx capensis), affected by high food density patches

AbstractTo determine the effects of their movement patterns, seven Cape clawless otters Aonyx capensis were caught in two rivers and radio‐tracked between 1993 and 1995. Total range length varied from 4.9 to 54.1 km and core length from 0.2 to 9.8 km. Total area of water used varied between 4.9 and 1062.5 ha, and core areas from 1.1 to 138.9 ha. As predicted using the resource dispersion hypothesis, total home‐range length was correlated with mean reed bed (high food density patch) nearest neighbour distance. The pattern of home‐range use by females was suggestive of territoriality. Male Cape clawless otters had overlapping home ranges, both with other males and with females.

Resource dispersion and consumer dominance: scavenging at wolf‐ and hunter‐killed carcasses in Greater Yellowstone, USA

AbstractThe Greater Yellowstone Ecosystem in the northern Rocky Mountains provides the context for a natural experiment to investigate the response of consumers to resources with differing spatial and temporal dispersion regimes. Grey wolves (Canis lupus) and human hunters both provide resource subsidies to scavengers by provisioning them with the remains of their kills. Carrion from hunter kills is highly aggregated in time and space whereas carrion from wolf kills is more dispersed in both time and space. We estimated the total amount of carrion consumed by each scavenger species at both wolf and hunter kills over 4 years. Species with large feeding radii [bald eagles (Haliaeetus leucocephalus) and ravens (Corvus corax)], defined as the area over which a consumer can efficiently locate and integrate resources, dominated consumption at the highly aggregated hunter kills whereas competitively dominant species [coyotes (Canis latrans)] dominated at the more dispersed wolf kills. In addition, species diversity and the evenness of carrion consumption between scavengers was greater at wolf kills than at hunter kills while the total number of scavengers at hunter kills exceeded those at wolf kills. From a community perspective, the top–down effect of predation is likely to be stronger in the vicinity of highly aggregated resource pulses as species with large feeding radii switch to feeding on alternative prey once the resource pulse subsides.

Sentenced without trial: reviling and revamping the Resource Dispersion Hypothesis

The resource dispersion hypothesis (RDH) offers a predictive model for how, in heterogeneous environments, some animals may form groups even without any direct benefits from doing so. Revilla (2003) levels a number of criticisms at the RDH, all of which we feel can be easily clarified or resolved (we address them in the order they appear in his critique). We argue that the RDH, despite its long history and despite our own efforts, still lacks convincing evidence to reject it. On the contrary, we see it as having weathered its critics very well. While there is steadily accumulating evidence in support of the RDH, there are very few empirical tests that provide decent evidence against it.

What does the Resource Dispersion Hypothesis explain, if anything?

OikosVolume 101, Issue 2 p. 428-432 What does the Resource Dispersion Hypothesis explain, if anything? Eloy Revilla, Eloy RevillaSearch for more papers by this author Eloy Revilla, Eloy RevillaSearch for more papers by this author First published: 25 April 2003 https://doi.org/10.1034/j.1600-0706.2003.12087.xCitations: 18 Eloy Revilla, Dept of Applied Biology, Estación Biológica de Doñana, Spanish Council for Scientific Research-CSIC, Avenida de Maria Luisa, s/n, Pabellón del Perú, ES-41013 Sevilla, Spain (revilla@ebd.csic.es) and Dept of Ecological Modelling, UFZ-Centre for Environmental Res., Leipzig-Halle, Permoserstrasse 15, DE-04318, Leipzig, Germany Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume101, Issue2May 2003Pages 428-432 RelatedInformation

Home‐range use by white‐nosed coatis (Nasua narica): limited water and a test of the resource dispersion hypothesis

AbstractThe resource dispersion hypothesis (RDH) proposes that in a spatially and temporally heterogeneous environment the territory size of social carnivores increases as the dispersion of limited resources is more widely spaced, whereas group size is limited, independently, by the richness or abundance of those resources or key habitats. To assess if white‐nosed coatis Nasua narica behave in accordance with the RDH, the relationship between home‐range size and spatio‐temporal availability of resources in Mexican tropical dry forests with marked seasonal rainfall was examined. Specifically, home‐range sizes were compared at two study sites that were broadly similar but contrasting in resource abundance and dispersion. Home‐range estimates for seven white‐nosed coati bands varied between 45 and 362 ha. Home‐range size did not correlate with food resource abundance and was better explained by the dispersion of water sources during the dry season. Average home‐range size was three times greater at the site where water sources were more widely separated during the dry season. These results are in accordance with the predictions of the RDH, and provide an example where the critical resource determining range size and configuration is water.

Space use in lions, Panthera leo , in the Selous Game Reserve: social and ecological factors

Habitat qualities, such as food supply or access to refuges, often influence home-range size. Furthermore, such qualitative differences usually lead to conspecific competition over space, which can be an important factor in determining the distribution of individuals within populations. In carnivores, patterns of resource dispersion are hypothesized to determine home range-size and group size. But in contests over space (or other resources), larger groups usually dominate smaller ones, and group size should therefore also affect home-range size. Here I describe the space use of lions, Panthera leo, in the Selous Game Reserve, Tanzania, and ask whether space use is related to pride size, habitat, or relatedness. Home ranges varied in size, but size showed no correlation to number of adult females in the pride or to habitat type. Lions exhibited a significant preference for riverine and short-grass habitat, and a significant avoidance of acacia woodland. Habitat preference ratios largely reflected prey availability in each habitat. Outer areas, as well as core areas of home ranges, were often used by two or more prides. Overlaps showed no correlation to relatedness among prides or habitat type. Thus, whereas home-range sizes and overlaps were determined by factors that could not be revealed by demographic factors or analyses of habitat composition or genetic structure, lion space use within each home range seemed driven mostly by prey availability, which mainly varies with habitat type.

Spatial organization, group living and ecological correlates in low‐density populations of Eurasian badgers, Meles meles

Summary 1 Territoriality and group living are described in a low-density population of Eurasian badgers, Meles meles L., by studying the patterns of spatial grouping and territory marking, as well as the differences between individuals in some of their characteristics (body condition and dispersal) and in their space use (seasonally, periods of activity and interaction between pairs of individuals) under strong seasonal fluctuations in the availability of the key resource (young rabbits, Oryctolagus cuniculus L.). Finally, the role of the spatial distribution of the main prey (young rabbits) in the development of sociality was also studied in order to test some of the assumptions and predictions of the resource dispersion hypothesis (RDH). 2 Badgers were territorial, showing a flexible system of territory marking, which includes the marking of the most used areas (sett-latrines at the centres of activity) and additionally, at the smaller territories, a system of border-latrines in the areas of contact between territories. The maximum use of border-latrines was associated with the reproductive season, and that of sett-latrines with the season of food scarcity. 3 In the study area where badgers had rabbits as main prey, territories were occupied by small groups of animals, formed by one adult female who reproduced, one adult male who also showed signs of reproductive activity, the cubs of the year (if there was reproduction) and some animals born during previous years, which remained in their natal territory until their dispersal (normally during the mating season of their third or fourth year of life). This system was not strictly fixed as males, given the opportunity, expanded their territories to encompass additional females. Territories in another study site were occupied by one adult female (marked), plus the cubs of the year and another adult individual (unmarked). 4 In winter and spring dominant females and subordinates used only a small fraction of their territories, moved short distances, at a low speed and covering small areas per night. These seasons corresponded with the reproduction of rabbits (highest food availability). Dominant females were the only individuals using all the territory available in the summer (lowest food availability), when badgers had the worst body condition. Food availability increased again in autumn, as did body condition, while range sizes were again reduced. Dominant males used the same proportion of their territories over all seasons. However, in winter (reproductive season) they moved faster, over longer distances, and covered larger areas per period of activity. These results indicate that use of space by dominant males was affected by different factors from that of dominant females and subordinates. 5 RDH does not seem to explain group living in our populations because: (a) territoriality in each pair of primary animals was driven by different factors (trophic resources for females and females for males); (b) dominant males acted as expansionists; and (c) territory size was related to its richness and not to patch dispersion. 6 We propose an integrative hypothesis to explain not only group formation but also interpopulation variability in the social organization of badgers within ecological, demographic and behavioural constraints and in the light of current theory on delayed dispersal.

Environmental correlates of badger social spacing across Europe

AimThe European badger (Meles meles, innaeus 1758) has been a focus for numerous studies of behaviour, physiology and ecology and, in particular, for testing theories concerning the evolution of sociality. However, most of these studies originate from the British Isles, where the behavioural ecology of this species differs markedly from elsewhere across its pan‐Eurasian geographical range. We use data in the literature, from all available parts of the badger's distribution, to test whether environmental variables can explain observed variation in densities and social spacing.LocationWe used published data from studies across Europe (mainly in the western part of this region).MethodsData covered all of Europe, spanning Great Britain to Kazakhstan in lon‐gitude and Norway to Spain in latitude. We used simple and multiple linear regression models to test for environmental correlates of the following four dependent variables, recorded at exact study sites: (1) badger densities, (2) sett densities, (3) group sizes and (4) territory sizes. Independent variables were extracted at these same locations from meteorological databases of climate data from across Europe. Those used in the analyses were: (1) annual mean of mean monthly temperatures, (2) mean of the difference between mean January and July temperatures, (3) mean of the difference between minimum and maximum monthly precipitation and (4) annual mean of monthly actual evapotranspiration. We also tested for relationships between mean badger densities and mean values of environmental variables reported for whole countries.ResultsNone of the environmental variables correlated with group or territory sizes, or with whole country measures of badger densities. However, the annual difference in minimum and maximum temperature was consistently correlated with both badger densities and sett densities recorded at specific study locations, in both single‐variable and multiple regressions. We found these relationships disappeared when single mean values were used for all of the studies on the British Isles, although in doing so sample sizes were drastically reduced as well. Further investigation revealed that the original positive relationship was composed of negative trends among the data from Great Britain and continental Europe, when these were analysed separately. This has important implications for understanding the behavioural ecology of this species, as well as the general biases that spatial correlation may cause in studies comparing populations.Main conclusionsThe precise relationship between the temperature range variable and badger densities appears to be complicated. Nevertheless, because the annual difference in the minimum and maximum temperature is related, in some way, to seasonality, this implies that badger densities are associated with seasonal constraints, or some other constraint(s) that covary with seasonality. We suggest that, if models of sociality are either seasonally or density dependent, then this finding has an important bearing on why badger social behaviour is so different across Europe. In particular, we discuss the implications of these results for the most pervasive model of social organization in the badger, the resource dispersion hypothesis.

Group size versus territory size in group‐living badgers: a large‐sample field test of the Resource Dispersion Hypothesis

Badgers (Meles meles) have been the focus for the development of a pervasive model of social grouping behaviour, relevant to a number of carnivore species and other taxonomic groups – the Resource Dispersion Hypothesis (RDH). The RDH hypothesises that the dispersion and richness of resources in the environment provide a passive mechanism for the formation of groups, even without any direct benefits of group living. However, few studies have tested the RDH in the field. The principal prediction is that, as opposed to enlargement of territory sizes to accommodate more members, territory size (TS) is independent of group size (GS). Instead, TS is determined by the spatial dispersion of resources, while GS is independently determined by the richness of those resources. However, these predictions provide only weak correlative tests, especially in non‐experimental field studies. The first predicts an absence of correlation and is therefore prone to Type II error, especially given the small sample sizes and errors in estimating TS and GS of mammals in the field. We tested for independence of territory size and group size in all years with available data since the beginning of the long‐term badger study in Wytham Woods in 1974. We used two methods of TS estimation, a sequential Bonferroni technique to adjust for multiple inference tests, a combined analysis and an analysis with pooled data. This prediction of the RDH could not be rejected on the basis of any of these analyses. Given this evidence that other processes are independently determining group size and territory size, further predictions of the RDH will be worth investigating in considerable detail.