The changes in the dominance hierarchy over time of a complete field‐captured colony of Cryptomys hottentotus hottentotus

Abstract

With 7 figures in the text)The common mole-rat, Crypfomys h. hottentofus, is a social subterranean rodent occurring in colonies in which one female and one to three males are involved in reproduction and the remaining colony members are non-reproductive. Within each sex the reproductive animals are usually the largest and most dominant animals.The dominance hierarchy amongst a field-captured colony was linear (h =0.95, calculated from Landau's linearity index) soon after capture. The non-reproductive females were ranked low in the dominance hierarchy; many were subordinate to non-reproductive males. The order of capture of mole-rats was not related to the position in the dominance hierarchy. The hierarchy became non-linear (h=0.56) after six months in captivity during which two juvenile animals became adult. The breakdown in the hierarchy may result from the lack of opportunity in captivity for animals to disperse and establish satellite colonies, or from colony members becoming co-dominant in the hierarchy as a result of a rise in rank by young animals.Dominant mole-rats are involved in a greater proportion of interactive behaviours than subordinates. Popularity studies show that females tend to be more popular animals than males. The largest reproductive male was the least popular animal in the first study, whereas a beta male was the least popular animal in the second study period. The reproductive female was the most popular in both periods.

A comparison of the ecology of two populations of the common mole-rat, Cryptomys hottentotus hottentotus: the effect of aridity on food, foraging and body mass

“…It is a cooperative breeder living in colonies of between 2 and 14 individuals (Bennett 1989;Spinks 1998). It exhibits a reproductive division of labour with reproduction typically being restricted to the largest male and female within a colony (Bennett 1989(Bennett , 1992Rosenthal et al 1992;Spinks et al 1997). The common mole-rat is herbivorous, feeding mainly upon the underground storage organs (tubers, corms and bulbs) of a range of geophytes which it finds as it constructs the elaborate burrow system (Davies and Jarvis 1986;Bennett 1990, 1991).…”

“…as being either reproductive males, non-reproductive males, reproductive females or non-reproductive females. Applying the criteria of Bennett (1989Bennett ( , 1992 and Rosenthal et al (1992), reproductive males were identified as the heaviest male in the colony. Reproductive females could readily be identified by the presence of perforate vaginas and prominent teats.…”

“…Reproductive females could readily be identified by the presence of perforate vaginas and prominent teats. Moreover, Bennett (1989Bennett ( , 1992, Rosenthal et al (1992) and have demonstrated that the reproductive female tends to be the largest female colony member. Divergence between study sites in the mean body mass of corresponding age/sex-status categories was tested using the MannWhitney U-test.…”

The colony structure and social organization of the giant Zambian mole‐rat, Cryptomys mechowi

“…Within the genus, Cryptomys hottentotus hottentotus is found to have a loose social structure, in which dispersal events are believed to be frequent (Bennett & Rosenthal, unpubl.). In marked contrast, Cryptomys damarensis is as eusocial as the naked molerat Rosenthal, Bennett & Jarvis, 1992;Jarvis & Bennett, 1993). Between these two species occurs the social Mashona mole-rat, Cryptomys darlingi (Bennett, Jarvis & Cotterill, 1994;Gabathuler et al, 1996).…”

Seasonal changes in burrow geometry of the common mole rat (Rodentia: Bathyergidae)

“…The common mole-rat occurs in colonies of up to nine individuals in arid regions and up to 16 animals in mesic regions (Davies & Jarvis, 1986). It is a co-operative breeder and has a division of labour with reproduction typically being restricted to the largest dominant male and female within the colony who inhibit the reproduction of subordinates (Bennett 1989(Bennett , 1992Rosenthal et al 1992;Spinks et al 1997). It is herbivorous, feeding upon corms, bulbs and tubers of a range of geophytes which it finds "blindly" whilst constructing elaborate burrow systems (Reichman & Jarvis, 1989).…”