Paul D. Stewart

DENSITY‐DEPENDENT REGULATION OF BODY MASS AND CONDITION IN BADGERS (MELES MELES) FROM WYTHAM WOODS

Body mass and an index of condition for badgers (Meles meles) in a high-density population (Wytham Woods, UK) were examined between 1990 and 1997 and compared with the size of the groups with which individuals were associated. Both body mass and condition decreased as centered group size increased. Fecundity also declined with increasing centered group size. Female badgers exhibited the greatest effects of density-dependent constraints on body mass and condition in autumn, whereas for males the effect was most pronounced in spring.

Boundary faeces and matched advertisement in the European badger (Meles meles): a potential role in range exclusion

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

Vocal Repertoire in the European Badger (Meles meles): Structure, Context, and Function

Vocalizations and behaviors of wild European badgers ( Meles meles ) were recorded using infrared video surveillance systems in Wytham Woods, Oxfordshire, United Kingdom. A quantitative acoustic analysis was undertaken, and the following acoustic parameters were measured from audio spectrograms: fundamental frequency bandwidth, duration, units per call, and inter-call interval. Sixteen discrete adult and cub sounds are described that form the basis of the European badgers vocal repertoire. Eight of these basic vocal categories are exhibited by adults and cubs. Churrs, purrs, and keckers are restricted to adults, and chirps, clucks, coos, squeaks, and wails are confined to the cubs repertoire. The majority of call types are low- to moderate-pitched and noisy. The sound system of the badger exhibits further complexity by way of gradations and transitions and is therefore best described as possessing a mixed vocal repertoire. Acoustic structure of call types is correlated with call function (inferred from context). No evidence of either alarm calls to conspecifics or the putative long-range ‘scream’ vocalization was found. A preliminary comparison of vocal signaling within the Mustelidae may add credence to the view that the vocal repertoire could serve as a potential indicator of social complexity. An Internet site, containing digital sound files representative of the call types described in this paper can be found at [http://users.ox.ac.uk/∼wcruinfo][1]. [1]: http://users.ox.ac.uk/%E2%88%BCwcruinfo

Vigilance in badgers Meles meles: the effects of group size and human persecution

Potential costs to badgersMeles meles (Linnaeus, 1758) of living in groups may be offset by the ability of a group to either improve predator detection, or reduce the time each individual must be vigilant to attain a certain likelihood of predator detection. Using an infra-red video-surveillance system, we show that badgers emerge later from their dens in a population that has been repeatedly subjected to lethal control by humans as compared to badgers from a nearby, undisturbed population. We further illustrate that, despite the apparent lack of a visual or vocal alarm signal to alert group members to a threat, corporate vigilance increases and individual vigilance levels decrease as badgers aggregate in groups (up to 4). These results highlight the possibility that the role of (human) predation in badger social evolution has not been sufficiently considered.