Christina D. Buesching

Validating mammal monitoring methods and assessing the performance of volunteers in wildlife conservation - "Sed quis custodiet ipsos custodies?"

Abstract Many conservation organisations rely heavily on volunteers, and the government often relies on them to achieve tasks for which funding is insufficient—for example, the monitoring of trends in biodiversity on a national scale. Thus, it is critical to deploy non-professionals effectively. In this study we validated and calibrated the data collected by 155 volunteers, assisting with mammal monitoring at Wytham Woods, Oxfordshire, between April 2000 and December 2001. Tasks included small mammal trapping and handling, surveying and censusing for badgers, estimating deer population sizes from dropping counts, and transect surveys for mammal field signs. We analysed the effects of age, gender, previous experience, physical fitness and aptitude on volunteer performance using quantitative measures and qualitative scores. We found that (1) techniques that could be taught to volunteers without lengthy or specialist training were sufficiently accurate to yield reliable data, (2) with approximately half a day of training in each task, volunteers could produce reliable data, verified by professionals, and (3) volunteer teams brought considerable time savings to many tasks, compared with a single professional researcher. Our analyses show that physical fitness was a significant predictor of a volunteers ability to perform tasks well and, in our particular sample, a male-bias in volunteer aptitude was apparent in some tasks. Previous experience as a conservation volunteer did not enhance performance over that of novices nor did age have any effect on volunteers’ ability. The overall veracity of volunteer data compared well with data collected using more specialist methods or collected by professional researchers using the same method. Volunteers required more time per task and, while they showed a tendency to underestimate population sizes, their results were consistent. Additionally, the programme helped to raise the environmental awareness of volunteers and their understanding of woodland ecology.

MALE-BIASED MOVEMENT IN A HIGH-DENSITY POPULATION OF THE EURASIAN BADGER (MELES MELES)

Abstract We investigated movement patterns in a high-density population of Eurasian badgers (Meles meles) to explore how the costs and benefits of dispersal and other forms of movement differed among individuals in the population. We analyzed a 17-year data set comprising 5,255 trapping events for members of a population of Eurasian badgers at Wytham Woods, Oxford, United Kingdom. For a subset of badgers with a sufficient trapping history, we were able to identify dispersal events. Permanent dispersal was not common. Of 267 badgers 1st trapped as young and caught on a minimum of 4 occasions spanning 400 days or more, the majority (75.8%) were never captured at more than 2 social groups. Only 51 (19.1%) of these animals satisfied our definition of dispersal; 96 (35.8%) were never captured outside of their natal social group. Male badgers moved between groups more than did females and accumulated more wounds in the process. Dispersing males tended to move to larger groups and to groups with a preponderance of females, but dispersal rate did not change as the density of the population increased. However, evidence of extraterritorial matings suggests that inbreeding may be alleviated without dispersal. We consider the implications of these findings for the mating system and social behavior of the badger.

The social function of allo-marking in the European badger (Meles meles)

The adaptive significance of sociality in European badgers (Meles meles) is often explained on the basis of ecological factors, but little is known about their social interactions. Here, we investigate how allo-marking of conspecifics with subcaudal gland secretions might serve as a behavioural mechanism to create a shared group-odour, thus functioning simultaneously to maintain group cohesion, and as an individual advertisement signal. The odour of subcaudal secretions, which encodes group-membership and individual-specific information, is partly generated by the bacterial flora in the subcaudal pouch. Studying the interactions of 40 different adults from two social groups, we analysed 3021 instances of allo-marking, which may be either mutual, i.e. two badgers pressing their subcaudal pouches against each other simultaneously (155 events) or sequential, i.e. one badger marking the body of another individual (2866 events). Sequential marking is significantly more frequent than mutual marking, although both occur significantly more often during the mating season and the cub-rearing season than at other times. Whereas mutual marking appears to be independent of individual-specific parameters, sequential allo-marking is strongly influenced by sex, age, and reproductive status. We propose that mutual marking generates a common group-smell by facilitating the exchange of pouch bacteria, thus aiding in group-cohesion, while sequential marking serves two purposes, to distribute the common group-smell, and to advertise individual-specific, fitness-related information. Strong correlation of the frequencies of sequential and mutual allo-marking as well as the allo-grooming behaviour between particular clusters of group members suggests the existence of sub-groups within badger groups.

AN ANALYSIS OF EURASIAN BADGER (MELES MELES) POPULATION DYNAMICS: IMPLICATIONS FOR REGULATORY MECHANISMS

Abstract Based on 15 years of observations of a badger (Meles meles) population at Wytham Woods in the central United Kingdom, we investigated which parameters governed demographic changes, using data recording the life histories of 868 individuals. We modeled the population in terms of a stage-classified matrix, giving an exponential population growth rate of r  =  0.063 (λ  =  1.065). Population elasticity values, derived from this matrix, produced a relative order of importance of regulatory parameters governing this population growth rate, of: adult survival (Pa) > fertility (F) > juvenile survival (Pj) > age at 1st reproduction (α) > age at last reproduction (ω). Thus, changes in Pa and F have the greatest potential to influence population growth rate. The population underwent a dramatic change in the last 5 years of the study, with a decline, then stabilization in population growth. However, this change was not related to any change in elasticity patterns between the 2 periods. Comparing the latter period to the preceding period of marked population growth revealed that fertility rate had little actual influence, whereas adult and juvenile survival rates were far more influential demographic variables. These findings prompted a 2nd, retrospective, analytical approach, a life-table response experiment (LTRE), revealing that the importance of Pj in the LTRE contrasted with its lesser prospective importance in the elasticity analysis. Change in fertility (ΔF) apparently had little environmental or genetic scope (according to the results of either technique) to influence regulation in this population. We also tested for delayed density dependence using the theta logistic model. Because territorial animals are expected to respond quickly to the effects of density dependence, corresponding to theta < 1, our rejection of this hypothesis indicated that the restrictions of territorial sociospatial regulation are relaxed in this badger population. These results are used to highlight population vulnerabilities.

Encounters between two sympatric carnivores: red foxes ( Vulpes vulpes ) and European badgers ( Meles meles )

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.

Variations in colour and volume of the subcaudal gland secretion of badgers (Meles meles) in relation to sex, season and individual-specific parameters

Summary Activity of scent glands is often related to an animals biological status. Here we investigate how endogenous parameters influence activity of the subcaudal gland tissue in European badgers ( Meles meles ). The large subcaudal glands produce a lipid-rich secretion which badgers frequently use for scent-marking. Earlier studies suggest that the smell of this subcaudal secretion is individual-specific and encodes information about group membership, but does not contain further information about individual-specific parameters (sex, age, body condition etc.). In this study the colour and volume of 975 subcaudal secretion samples collected between January 1996 and January 1999 were investigated and analysed in relation to sex, endocrinological and reproductive status, age, head body length and body condition of the badgers, and seasonality. The analyses show a distinct seasonal pattern, a significant sex difference in the secretions colour and volume, apparent throughout the year, and a strong influence of individual-specific parameters on the characteristics of the secretion. Thus, we conclude that the subcaudal secretion of the European badger could communicate more information about the marking individual than previously assumed. We propose that the function of subcaudal scent-marking is likely to be two-fold, to provide information about territory occupancy to non-group members at the periphery of territories and to act as an intra-group communication signal in the vicinity of the sett.

Coordinated Latrine Use by European Badgers, Meles meles: Potential Consequences for Territory Defense

Abstract The Active Territorial Defense Hypothesis (ATDH) and Passive Range Exclusion Hypothesis (PREH) are contrasted as possible explanations for patterns of latrine use in a high-density population of the European badger (Meles meles) in the United Kingdom. Using bait-marking techniques, temporal patterns in latrine use by individuals and social groups were investigated to test for any systematic marking behavior, especially whether coordination of individual actions might be involved in the group territorial marking strategy. Latrine use by 4 groups was concentrated primarily along territory boundaries and particularly along parts of the boundary closer to that groups sett, rather than closer to active feeding areas. Boundary latrines were used to a similar extent by each group, with a consistent percentage (but differing subset) of a groups boundary latrines used daily. Individually, badgers preferentially used certain latrines and male badgers, in particular, showed a tendency to deposit more feces in latrines closer to their group sett. Our results indicate that badgers partition the collective responsibility of marking their territories, with the result that their entire boundaries are marked regularly and consistently, regardless of where focal individuals may be feeding. Individuals did not simply defecate at the section of boundary closest to where they happened to be active, but rather according to a pattern resulting in comprehensive, regular group coverage of the border. The patterns of latrine use accorded more closely with the ATDH than the PREH. This study provides evidence that badgers may cooperate systematically to defend their territories.

Scent-Marking Behaviour of the European Badger (Meles Meles): Resource Defence or Individual Advertisement?

European badgers (Meles meles) are nocturnal mustelids. Unlike most other members of this family, which are mainly solitary or pair-living (Powell, 1979; Johnson et al., 2000), badgers live in closely related groups of up to 30 individuals (Rogers et al, 1997). However, the adaptive significance of group-living in this species remains unclear (e.g.Woodroffe and Macdonald, 1993). Incidences of truly co-operative behaviour have not as yet been reported, and although there is some evidence of allo-parental behaviour (Woodroffe, 1993), the benefit of apparent “helpers” for cub-survival appears to be negligible (Woodroffe and Macdonald, 2000). Other behaviours, such as allo-grooming, which are often considered as primitive forms of co-operation, appear to follow a “tit for tat” pattern in badgers (Macdonald et al., 2000). Thus, sociality in Meles meles is often explained instead on the basis of ecological factors, such as food distribution (Kruuk, 1978; Macdonald, 1983). It has only recently become possible to study in detail the behavioural repertoire underlying social group dynamics in badgers, as advances in remote infra-red video surveillance (Stewart et al., 1997b) have overcome the traditional problems of working with nocturnal species. Observations using this technique have already provided insights into sett-maintenance (Stewart et al., 1999) and dominance (Murphy et al., in press). It now offers great potential regarding scent-marking behaviour. In this paper we review the scent-marking behaviour of badgers along territory boundaries, at the sett, and in social context, and we discuss the significance of olfactory signals in the context of both resource defence and individual advertisement.

Diet of an opportunistically frugivorous carnivore, Martes flavigula, in subtropical forest

Abstract In response to foraging for foods that fluctuate in availability, generalists often exhibit the ability to switch between different food sources. Many of the Carnivora on an omnivorous–frugivorous diet display temporal dietary switching and specialism, but the mechanisms underlying this are incompletely understood. Here we studied the diet of the opportunistically frugivorous yellow-throated marten (Martes flavigula) with regard to food-resource exploitation in a subtropical forest of central China. Diet was determined through scat analyses combined with surveys to estimate local food abundance. Peak fruit consumption and the lowest utilization of small mammals occurred when fruit abundance reached its temporal maximum in the environment in synchrony with a concomitant peak in small mammal abundance. When both fruits and small mammals were least abundant in the environment, the martens diet shifted to the maximum utilization of small mammals with no fruit consumption. This dietary switching could not be explained by the fluctuation in the abundance of principal prey in the environment, that is, small mammals, but by the ease of procurement of fruit at peak fruiting season. The martens diet thus does not simply reflect primary resource abundance but is a function of the relative abundance and inferred availability of alternative food types. This case study of the yellow-throated marten provides insight into foraging strategies that depend on the relative, temporal availability of food types, a phenomenon observed for other generalist omnivores (including several Carnivora).

Climate and the Individual: Inter-Annual Variation in the Autumnal Activity of the European Badger (Meles meles)

We establish intra-individual and inter-annual variability in European badger (Meles meles) autumnal nightly activity in relation to fine-scale climatic variables, using tri-axial accelerometry. This contributes further to understanding of causality in the established interaction between weather conditions and population dynamics in this species. Modelling found that measures of daylight, rain/humidity, and soil temperature were the most supported predictors of ACTIVITY, in both years studied. In 2010, the drier year, the most supported model included the SOLAR*RH interaction, RAIN, and30cmTEMP (w = 0.557), while in 2012, a wetter year, the most supported model included the SOLAR*RH interaction, and the RAIN*10cmTEMP (w = 0.999). ACTIVITY also differed significantly between individuals. In the 2012 autumn study period, badgers with the longest per noctem activity subsequently exhibited higher Body Condition Indices (BCI) when recaptured. In contrast, under drier 2010 conditions, badgers in good BCI engaged in less per noctem activity, while badgers with poor BCI were the most active. When compared on the same calendar dates, to control for night length, duration of mean badger nightly activity was longer (9.5 hrs ±3.3 SE) in 2010 than in 2012 (8.3 hrs ±1.9 SE). In the wetter year, increasing nightly activity was associated with net-positive energetic gains (from BCI), likely due to better foraging conditions. In a drier year, with greater potential for net-negative energy returns, individual nutritional state proved crucial in modifying activity regimes; thus we emphasise how a ‘one size fits all’ approach should not be applied to ecological responses.