Extra Territorial Excursions by European badgers are not limited by age, sex or season

Abstract

european badgers (Meles meles) in medium and high density populations show strong territorial behaviour. territories in these populations are contiguous, well-marked and often unchanging over many years. However, badgers do not always stay within their territorial boundaries. in our mediumdensity population, most individual badgers made extraterritorial excursions (etes) throughout the year. etes were most frequent between April and September and least frequent in December and January (the period of winter lethargy). Male badgers made longer and more frequent etes than females (especially between January and March, and in autumn). Breeding females made longer and more frequent etes than non-breeding females in november. While these peaks correspond with the main mating seasons, mating activity does not explain etes throughout the year. the shorter, but more frequent, etes in summer months may serve a monitoring purpose, rather than simply providing additional mating opportunities with badgers from outside the 'home' social group. We found that young badgers did not make regular etes until the summer of their second year. if badgers could be vaccinated as cubs, this would reduce any potential risk of tB spread during etes. In the classic view of badger social organisation 1,2 , badgers live in social groups, which share a communal territorial space. Boundaries between adjoining social groups are marked by latrines. These latrines are often linked by well-trodden paths, which suggest that badgers patrol the borders between territories 1. If such territorial behaviour were strictly maintained, then, with the typically low dispersal rates reported in badgers (Table 1), this should lead to major inbreeding. However, relatedness within social groups is much lower than this strict territorial behaviour predicts 3. Observational evidence has identified badgers of both sexes making temporary visits to other social groups for mating purposes 7,8. These visits have been described as extraterritorial excursions (ETEs) 8 , as the badger leaves their home territory and enters the territory of a different social group. Research conducted in Wytham Woods, Oxfordshire (a very high density population) showed that just less than 50% of cubs in any given social group were sired by males from within that group 9. Furthermore, a single litter could contain cubs sired by males from different social groups 10. This identified a polygynandrous mating system in badgers, i.e. both males and females have multiple mating partners during a breeding season. As female badgers can delay the implantation of fertilised eggs 8 and allow the development of different embryos at different times (i.e. superfetation) 11 , they are released from the limitation of seasonal breeding cycles. It would, therefore, appear that female badgers would be as likely as males to benefit from visits to other social groups for extra-group matings, at any time of year. Territorial, group-living species are susceptible to inbreeding depression 12 , which can reduce fitne...

Impact of test, vaccinate and remove protocol on home ranges and nightly movements of badgers in a medium density population

“…At this density, badgers have been observed to engage in inter-group movements more frequently which is thought to facilitate breeding and foraging 47 . It has therefore been suggested that at lower population densities, increased inter-group movements and reduced competition for resources lessen the motivation for permanent displacement in response to culling 47 , 48 . Another corollary of increased inter-group movement is that vaccination of badgers may be particularly effective in reducing transmission when increased contact between social groups exists, which reduces badger-to-badger bTB transmission 88 and thereby spillover of bTB from badgers to cattle but does not prevent cattle-to-badger transmission.…”

abmAnimalMovement: An R package for simulating animal movement using an agent-based model

“…60,63 Badger movements are also impacted by their territoriality, avoiding areas occupied by other badger groups, but also displaying occasional extra-territorial movements. 59,61 This suggests a general, but not complete avoidance of areas occupied by other badger groups.…”

“…We also want to allow the exploratory (state 1) movements to be great enough to occasionally exceed the normal home range or territory. 61 We can draw on statements regarding maximum distance travelled in a night from papers such as, Refs. 58, 60 and 62 to approximate how distance foraging locations could be from a sett, While also confirming the nocturnal activity cycle for the badger.…”

“…Exhibits site fidelity via the use of two shelter sites 58,59 2. Movement speed approximated by summary statistics from previous studies, 58,60,62 while constrained by terrestrial environment and territoriality 59,61 3. An 8-12 hour activity cycle, that shifts over the year 60,63 2…”

An investigation of Mycobacterium bovis and helminth coinfection in the European badger Meles meles

“…At higher densities t hey are territorial ( Palphramand et al, 2007 ), live in social groups and defend their territories with active fighting, which is effective in spreading tuberculosis between individuals ( Corner et al, 2011 ). Badgers regularly range outside their territories both for mating ( Kelly et al, 2020 ) and while dispersing ( Gaughran et al, 2019 ). In addition, some males hold territories comprising more than one social group ( Gaughran et al, 2018 ).…”