Multi-generational persistence of traditions in neighbouring meerkat groups

Reports of socially transmitted traditions based on behavioural differences between geographically separated groups of conspecifics are contentious because they cannot exclude genetic or environmental causes. Here, we report persistent differences between neighbouring groups of meerkats (Suricata suricatta) where extensive gene flow precludes genetic differentiation. Over 11 years, some groups consistently emerged later from their sleeping burrows in the morning than others, despite complete turnovers in group membership and the influx of immigrants. Group territories overlapped and, in many cases, the same sleeping burrows were used by different groups. Differences persisted even after accounting for effects of group size, weather and burrow characteristics, and were unrelated to food availability within territories. These results provide compelling evidence that the emergence times of meerkat groups represent conservative traditions.     

The development of foraging microhabitat preferences in meerkats

Animals of many species tend to target their foraging attemptstoward particular microhabitats within their habitat. Althoughthese preferences are critical determinants of the foragingniche and have important ecological and evolutionary implications,we know little about how they develop. Here, we use detailedlongitudinal data from meerkats (Suricata suricatta) to examinehow individual learning and the use of social information affectthe development of foraging microhabitat preferences. Despiteliving in an open, arid environment, adult meerkats frequentlyforaged at the base of vegetation. Young pups seldom did so,but their foraging microhabitat choices became increasinglyadult-like as they grew older. Learning about profitable microhabitatsmay have been promoted in part by positive reinforcement fromprey capture. Foraging may also have become increasingly targetedtoward suitable locations as pups grew older because they spentmore time searching before embarking on foraging bouts. Thedevelopment of microhabitat preferences might also have beeninfluenced by social cues. Foraging in close proximity to adultsmay increase the probability that pups would dig in similarmicrohabitats. Also, pups often dug in holes created by olderindividuals, whereas adults never dug in existing holes. Foragingin existing holes was no more profitable to pups than creatingtheir own foraging hole but could provide pups with importantinformational benefits. The integration of personal and socialinformation is likely to be a common feature in the developmentof the foraging niche in generalist species.     

Cooperative personalities and social niche specialization in female meerkats

The social niche specialization hypothesis predicts that group‐living animals should specialize in particular social roles to avoid social conflict, resulting in alternative life‐history strategies for different roles. Social niche specialization, coupled with role‐specific life‐history trade‐offs, should thus generate between‐individual differences in behaviour that persist through time, or distinct personalities, as individuals specialize in particular nonoverlapping social roles. We tested for support for the social niche specialization hypothesis in cooperative personality traits in wild female meerkats (Suricata suricatta) that compete for access to dominant social roles. As cooperation is costly and dominance is acquired by heavier females, we predicted that females that ultimately acquired dominant roles would show noncooperative personality types early in life and before and after role acquisition. Although we found large individual differences in repeatable cooperative behaviours, there was no indication that individuals that ultimately acquired dominance differed from unsuccessful individuals in their cooperative behaviour. Early‐life behaviour did not predict social role acquisition later in life, nor was cooperative behaviour before and after role acquisition correlated in the same individuals. We suggest that female meerkats do not show social niche specialization resulting in cooperative personalities, but that they exhibit an adaptive response in personality at role acquisition.     

Individual contributions to territory defence in a cooperative breeder: weighing up the benefits and costs

While investment in territory defence is expected to be influenced by its benefits, the additional role that costs may play is rarely considered. Here, we quantify both benefits and costs of repelling prospecting males in cooperative meerkats, and demonstrate that both are required to explain the substantial variation in individual contributions to the defence observed. Males benefit more from repelling prospectors than females, as males may lose dominance and be expelled during intrusions. Accordingly, males invest the most in repelling prospectors. We also show that males experience an associated cost in the form of reduced weight gain and, as such, heavier males contribute more to chasing prospectors. Finally, we show evidence of a cost not restricted to individuals engaged in chasing: both males and females reduce their contributions to feeding dependent pups when prospectors are present, resulting in a reduction in pup weight gain in this context. Males appear to adjust their contributions to chasing in light of this cost, chasing at lower rates when their group contains dependent young. Our findings support the view that investment in cooperative behaviours can be attributed to benefits and costs, and highlight the additional importance of considering trade-offs in investment between cooperative behaviours.     

Nonlinearities in Meerkat Alarm Calls Prevent Receivers from Habituating

Despite the fact that nonlinearities are present in the calls of a number of different species, their adaptive function has received little empirical investigation. Previous studies have demonstrated that playbacks of nonlinear calls evoke a more extreme behavioural response and lead to an increase in responsiveness compared with control playbacks without nonlinearities. Consequently, it has been suggested that nonlinearities might prevent receivers from habituating, by increasing the unpredictability of the call (‘unpredictability hypothesis’). In this study, we tested the unpredictability hypothesis, specifically whether nonlinearities prevent receivers from habituating, by means of a playback experiment using meerkat (Suricata suricatta) alarm calls. We found that in meerkats, playbacks of naturally occurring nonlinear alarm calls take longer to habituate to than alarm calls without any nonlinear intrusions. These data provide important empirical support for the hypothesis that nonlinearities are not just an irrelevant by‐product of the vocal production system, but indeed function adaptively.