Rare cases of plural breeding in captive and wild naked mole-rats: insights into social and reproductive dynamics

Plural breeding, the simultaneous reproduction of more than one female within a social group, is rarely observed in highly social mammals such as the naked mole-rat (Heterocephalus glaber), where reproduction is typically monopolized by a single dominant queen. This study documents and analyses four rare cases consistent with plural breeding, two in captivity and two in wild colonies, to investigate their social and reproductive dynamics. In the two captive colonies, plural breeding occurred during periods of social instability, including early colony formation and episodes of internal social fragmentation. Concurrent reproduction was confirmed in three colonies, while in one wild colony only single litters were captured and the maternal identity of the two queens remained uncertain. In the confirmed cases, the plural breeding females were closely related (mother–daughter or sisters), whereas relatedness could not be determined for the wild colony. Both breeding females gave birth within a short time frame in three of the colonies. All litters were successfully raised, with allonursing observed in one captive colony. In this colony, where detailed data were available, reproductive parameters such as litter size, pup survival, and growth did not differ markedly between the simultaneously breeding females. In three colonies with follow-up data, plural breeding was short-lived, ending either with the removal of one queen following escalated aggression, or with the unexplained disappearance of one queen. Although limited to four colonies, these observations raise the possibility that these rare cases of plural breeding in naked mole-rats may occasionally arise when dominant queens are temporarily unable to maintain full reproductive control over their sexually suppressed female subordinates. These findings may provide empirical observations relevant to understanding the mechanisms that maintain, but occasionally fail to enforce, reproductive skew in highly cooperative mammals.