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Mammalian Biology

, Volume 71, Issue 4, pp 203–213 | Cite as

Social monogamy in the noki or dassie-rat (Petromus typicus) in Namibia

  • Galen B. RathbunEmail author
  • Carolyn D. Rathbun
Original investigation

Abstract

The noki or dassie-rat (Petromus typicus) is a little-studied diurnal hystricognath rodent endemic to rocky outcrops in south-western Africa. An intermittent study in Namibia of 11 radio-tagged individuals, with over 250 h of direct observation, was done between 2000 and 2004 to document their basic natural history, including their social organization. The study was terminated when noki numbers collapsed, probably due to predation by an expanding population of black mongooses (Galerella nigrata) that was unintentionally provisioned with food at a nearby eco-tourist lodge. Male and female adults were distributed as monogamous pairs on home ranges that were similar in size and shape. The pair bond was strong, with many coordinated behaviours. Reproduction was seasonal with litters of single highly precocial young. Multiple generations remained on the parental home range without significant aggression. Most aggression was between adult males, while adult females showed tolerance towards each other and intruding adult males. Although noki social monogamy is probably the result of male mate guarding, considerable paternal care was observed, including allogrooming and vigilance against predators. Nokis have a relatively low metabolic rate and numerous thermoregulatory behaviours that suggest that nocturnal huddling by the male with his mate and young may be an important factor in the evolution of their social monogamy.

Key words

Petromus dassie-rat monogamy Namibia social organization 

Soziale Monogamie der Felsenratte (Petromus typicus) in Namibia

Zusammenfassung

Die Felsenratte (Petromus typicus, auch Noki genannt) ist ein bisher wenig untersuchtes, tagaktives Nagetier (Unterordnung Hystricognatha), das nur in felsigen Gebieten und Felsspalten im südwestlichen Afrika vorkommt. In den Jahren 2000 bis 2004 wurde eine zeitweilige Untersuchung von elf mit Radiosendern versehenen Individuen in Namibia durchgefü hrt. Die Tiere wurden während über 250 Stunden direkt beobachtet, um deren natü rliche Lebensweise und Sozialstruktur zu dokumentieren. Die Studie wurde abgebrochen, als die Anzahl Felsenratten kollabierte. Grund dafür war wahrscheinlich die Bejagung durch eine wachsende Population von schwarzen Mangusten (Galerella nigrata), die unbeabsichtigt in einer nahegelegenen Touristenlodge gefü ttert wurden.

Adulte Felsenrattenmännchen und -weibchen hielten als monogame Paare Territorien inne, die in Grösse und Form ähnlich waren. Die starke Paarbindung war durch viele koordinierte Verhaltensabläufe geprägt. Die Fortpflanzung war jahreszeitlich bedingt und bestand aus einem einzigen nestflüchtenden Jungen. Mehrere Generationen blieben im elterlichen Territorium ohne massgeblich Aggressionen zu zeigen. Die meisten Aggressionen traten zwischen erwachsenen Männchen auf, während ausgewachsene Weibchen Toleranz gegenüber anderen Weibchen und eindringenden Männchen zeigten. Obwohl die soziale Monogamie der Felsenratten wahrscheinlich das Resultat von Partnerverteidigung durch die Männchen ist, wurde beachtliche väterliche Fürsorge beobachtet, wie beispielsweise Allogrooming und Wachsamkeit gegenüber Feinden. Nokis haben eine relativ geringe metabolische Rate und zahlreiche thermoregulatorische Verhaltensweisen lassen vermuten, dass das nächtliche Zusammenkuscheln von Männchen und deren Paarungspartnern und Jungen ein wichtiger Faktor in der Evolution ihrer sozialen Monogamie sein könnte.

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Copyright information

© Deutsche Gesellschaft für Säugetierkunde 2006

Authors and Affiliations

  1. 1.Department of Ornithology and MammalogyCalifornia Academy of SciencesSan FranciscoUSA
  2. 2.CambriaUSA

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