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Many mammal species are thought to adopt solitary living owing to mothers becoming intolerant of adult offspring and the occurrence of social intolerance between adults. However, field studies on how solitary mammals interact are rare. Here we show that solitary living can occur without social intolerance. Over 3 years, we recorded interactions between free-living bush Karoo rats (Otomys unisulcatus) and conducted dyadic encounter experiments between kin and non-kin female neighbours, both in a neutral test arena and in field intruder experiments. Social interactions were rare (230/2062 observations), and they were aggressive in only 34% of cases. In dyadic encounters, mothers interacted amicably with young offspring. Aggression between mothers and offspring was almost absent. This mother–offspring relationship remained amicable even after adult offspring had dispersed. Aggression between neighbouring adult females was low in neutral arena tests, independent of kinship and season. However, in the field, females reacted more aggressively towards non-kin than kin intruders, especially during the breeding season. Tolerance between mothers and adult offspring indicates that aggression is not the mechanism leading to dispersal and solitary living. We found a solitary social system characterized by social tolerance, suggesting that dispersal and lack of social attraction rather than aggression can lead to solitary living. [ABSTRACT FROM AUTHOR]

Comparative studies on social evolution are ideally based on large datasets to ensure high statistical power, but their scientific validity also relies on the quality of the data. However, even though social organisation, that is the composition of social units, is measured in many field studies testing specific hypotheses, these data are often not adequately reported. Here, we summarise which data on social organisation should always be reported regardless of the study focus to make them available for comparative studies. As an example, we report data from a literature survey on one of the four superorders of placental mammals, the Xenarthra from South America (armadillos, anteaters and sloths), of which all 30 species are generally assumed to be solitary living. In total, we found 4510 articles. The titles and abstracts of 61 publications indicated that data on social organisation were collected, but only 12 publications contained sufficient information for us to determine the social organisation. We found reliable information on nine species, of which seven were strictly solitary. Two species showed a combination of solitary‐living and pair‐living with one including female groups. This review therefore indicates that Xenarthra may not be exclusively solitary. Our literature survey further shows that valuable data are often not reported even though it can be assumed that these data had been collected. We report examples from 23 additional studies on monotremes, marsupials and two other placental superorders showing similar issues in reporting data. It is important to make authors aware that this information would be valuable for comparative studies. In sum, we recommend including data on the composition of social units, sex of individuals, occupancy of sleeping sites, frequency of observations and trapping events, home range overlap and the proportion of the individuals in the study area, independent of the study question in all publications. [ABSTRACT FROM AUTHOR]