The individual within the group territorial system of the European badger (Meles meles L.)
Three groups of European badger (Meles meles L.) were studied during 1985 and 1986 on an area of mixed farmland in the Spey Valley, Scotland. The European badger is group territorial but individuals forage solitarily. Group size was 6 (Milton group), 3-5 (Sheilich group) and 2-4 (Little Loch group). Data were obtained by means of radio tracking on five of the Milton group, three of the Sheilich group, two of the Little Loch group plus two single males. The three group territories ranged in size from 75-146 ha. and each contained a unique habitat structure. Spatial autocorrelation and graphical analyses indicated that individuals within each group distributed their intensity of use of the group territory similarly; the three groups, however, differed from one another in this respect. When examined over the long-term, individuals' total ranges and core areas overlapped widely, however, overlap of 50x50 m grid cells was low between pairs of individuals and the individual and the rest of the group suggesting partial spatial separation of individuals within the group. Over three week intervals the Milton badgers showed a complex, shifting arrangement of activity centres with no association between particular group members. On a nightly basis, an individual's total range overlapped widely with the rest of the group, but spacing of observation points for all individuals suggested that each individual's movement was concentrated in relation to the movements of the rest of the group. Diet comparisons between groups, within groups between years and between seasons suggested that availability, as indicated by the differing vegetational composition of each group territory, affected diet. Initial evidence was that individual's diets were similar within groups. Individuals within the three groups had similar range composition, showed similar preferences for the vegetation zones within each group territory and appeared to use the zones similarly. Individuals within each group exploited the group territory similarly, at least within the sensitivity of the present data. Above surface activity was strictly nocturnal and individuals showed the same pattern of varying length activity bouts interspersed with periods of rest underground; there was no common schedule, however, between individuals. Overall activity budgets were similar between individuals within the group. Individuals used the same ongoing movements each night, often travelling 3-4km, returning occasionally only to those areas that had received light use earlier in the night, and avoiding previously used areas more than expected from models of random badger movement. Group members were seldom observed in close proximity and appeared to be either spacing themselves each night randomly or avoiding one another. The three groups differed in the distribution of communal defaecation sites (latrines). All group members visited latrines and latrine paths, behaviours associated with demarcation of the group range, at similar rates. It is suggested that the spatial organization of the three groups of badgers was non-competitive. At first glance, the data indicated a large potential for spatial competition, however, a detailed analysis suggests that group members intensively used a number of different parts of the group territory ('patches'), these were shared with only a part of the group, and individuals were seldom in close contact with one another on a given night as predicted by patch based models of Carnivore group territoriality. However, territory size and configuration were not determined by the location of key feeding areas, in contradiction to the patch based models. Possible advantages gained by individuals within the group by spatial non-competitiveness are discussed in light of possible territory inheritance by related individuals. Possible advantages to all individuals contributing to demarcation of the group territory are also discussed. Group formation in European badgers is also compared with a model of group formation in birds.