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Jordan N.R.,University of Cambridge | Mwanguhya F.,University of Cambridge | Mwanguhya F.,Banded Mongoose Research Project | Kyabulima S.,University of Cambridge | And 3 more authors.
Journal of Zoology | Year: 2010

Scent marking is commonly described as a territorial behaviour, and scent marks might deter potential intruders from entering occupied areas. Conspecific neighbours present both a reproductive and a territorial threat, thus, determining which, if any, of these threats shapes scent-marking behaviour is difficult. Banded mongooses Mungos mungo provide a rare clear separation between reproductive rivals (found within groups) and territorial rivals (neighbouring groups), because immigration into social groups is extremely rare, and mating occurs almost exclusively within groups. This situation offers an opportunity to assess the relative importance of territorial defence and intra-group competition for mates in shaping scent-marking behaviour. We combined detailed behavioural observations of scent marking, chemical analyses of scent composition and discrimination experiments in the field, and found little evidence for higher rates of scent marking in overlapping areas, a lack of group specificity of scents and a failure of individuals to discriminate between the scents of different groups. Although scent may fulfill some role in territorial demarcation and defence, these results suggest that scent marks and scent-marking patterns are also involved in communicating within social groups. © 2009 The Zoological Society of London. Source

Furrer R.D.,University of Zurich | Kyabulima S.,Banded Mongoose Research Project | Willems E.P.,University of Zurich | Cant M.A.,University of Exeter | Manser M.B.,University of Zurich
Behavioral Ecology | Year: 2011

In social species that cooperatively defend territories the decision to retreat or attack in contests between groups is likely to depend on ecological and social factors. Previous studies have emphasized the importance of the encounter location or the size of competing groups on the outcome. In addition, the identity of the intruder, whether familiar or stranger, may also play a role. To test whether the same factors affect the resident group's decisions already at the beginning of contests, we simulated intergroup encounters in banded mongooses (Mungos mungo). When spotting rival groups banded mongooses emit "screeching calls" which lead group members to bunch up. With playbacks of these calls, we tested how the groups' response was affected by the following factors: 1) the location of the playback in relation to their territory (exclusive use vs. overlap); 2) the number of resident individuals; and 3) the origin of calls (neighbor vs. stranger) used. Subjects were more likely to approach the loudspeakers and arrive within 1 m of the speakers in the exclusive use zone than in the overlap zone. Moreover, larger groups tended to be more likely to move toward the loudspeakers and were also more likely to arrive there. The origin of calls used in the playbacks did not affect the groups' responses. These findings exemplify the importance of the combined effect of location and group size on group decisions during impending intergroup contest. © The Author 2011. Source

Nichols H.J.,University of Cambridge | Amos W.,University of Cambridge | Bell M.B.V.,University of Cambridge | Bell M.B.V.,University of Edinburgh | And 3 more authors.
Animal Behaviour | Year: 2012

In cooperatively breeding vertebrate societies, contributions to offspring care can vary greatly between group members. Kin selection theory predicts that cooperation will be favoured when directed towards relatives and when the cost to benefit ratio is low. The fitness costs of helping in turn depend on the impact of energetic investments in care on future reproductive success, which is likely to vary between helpers. For example, investments may impact more on a young helper, which needs to invest energy in growth and is an inexperienced forager. We investigated how a key predictor of cost, food availability (estimated using rainfall), influences helping behaviour in the banded mongoose, Mungos mungo. In this cooperative carnivore, a variable number of group members breed while almost all help to rear the communal litter. Nonbreeding females and juvenile males helped less when food was scarce, reflecting the potentially high costs of weight loss and reduced growth on survival and future reproductive success. In contrast, adult males maintained their investment in care as food supply decreased, probably because body condition has relatively little impact on male reproductive success in this species. Breeding females (with pups in the communal litter) also maintained their helping effort as food supply decreased. Although mothers invested highly in care, there was no evidence that they preferentially cared for their own pups, probably because synchronized birthing scrambles maternity cues. Patterns of care in the banded mongoose thus seem to reflect the benefits gained from helping and the long-term fitness costs to the helper. © 2012 The Association for the Study of Animal Behaviour. Source

Jordan N.R.,University of Cambridge | Manser M.B.,University of Zurich | Mwanguhya F.,University of Cambridge | Mwanguhya F.,Banded Mongoose Research Project | And 4 more authors.
Animal Behaviour | Year: 2011

Overmarking occurs when one individual places its scent mark directly on top of the scent mark of another individual. Although it is almost ubiquitous among terrestrial mammals, we know little about the function of overmarking and detailed field observations are rare. We investigated the chemical composition of scents and patterns of overmarking by wild banded mongooses, Mungos mungo. Chemical analyses of anal gland secretions showed that scents were sexually dimorphic. Both male and female adults were more likely to overmark the scents of same-sex individuals. An analysis of responses to two scents on the same site suggested that the sex of the top or most recent scent was more important than that of the bottom or original scent in determining overmarking response. Juveniles also overmarked scents at high rates, but did not respond to scents in a sex-specific way. Same-sex-specific patterns within groups have not been described in any other species, and may reflect a social system with intense intrasexual competition for reproduction within both sexes. Banded mongooses live in large mixed-sex groups, with intense competition between males for females, owing to the heavily male-biased adult sex ratio and highly synchronized oestrous cycles. Oestrous synchronization may also promote intrasexual competition for males within females, as females compete simultaneously for high-quality males. Female competition for males may also be enhanced by the rewards of male-biased parental care. This investigation highlights the need for detailed studies of overmarking in the natural context, to confirm and expand upon laboratory findings. © 2010 The Association for the Study of Animal Behaviour. Source

Jordan N.R.,University of Cambridge | Mwanguhya F.,University of Cambridge | Mwanguhya F.,Banded Mongoose Research Project | Furrer R.D.,University of Zurich | And 4 more authors.
Animal Behaviour | Year: 2011

Sexual selection has resulted in the elaboration of secondary sexual characteristics in many animals. Although mammalian scent glands, secretions and marking behaviour are commonly sexually dimorphic, these traits have received little attention compared to avian plumage and mammalian weaponry. Overmarking, when one individual places a scent mark directly over that of another individual, is of particular interest. Owing to the costs of repeatedly monitoring and covering the scent marks of rivals, overmarking may provide an honest indication of a male's resource-holding potential, perhaps explaining why female rodents exposed to experimental overmarks subsequently prefer to associate with males whose scent mark was on top. This study on wild banded mongooses, Mungos mungo, suggests that overmarking may primarily affect behavioural mating success through male competition not by female mate choice. First, chemical analyses of anal gland secretions demonstrated that males had individually distinctive scents, and a field experiment confirmed that mongooses were able to discriminate between scents from different individuals. Observations of overmarking patterns showed a relationship between overmarking score and behavioural mating success, but we found no evidence that females actively chose to mate with males with high overmarking scores. Instead, we found that males with higher overmarking scores first mate-guarded females at a significantly younger age than males with lower overmarking scores. Since mate-guarding males obtain the vast majority of matings, this suggests that overmarking may be an important component of intrasexual competition for mating opportunities in this species. © 2010 The Association for the Study of Animal Behaviour. Source

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