Overmarking behaviour of zebra males: no scent masking, but a group cohesion function across three species
Among many hypotheses in the literature that explain overmarking in mammals, most studies favour a sexual selection hypothesis. However, results in the literature are conflicting. In this study, we tested two hypotheses that could explain overmarking by males: (i) as a part of sexual selection, more specifically to mask scent of receptive females and (ii) as a form of communication serving to aid group cohesion. We observed each of the three zebra species in eight different herds at four zoos. In total, we recorded 1395 eliminations (760 defecations, 635 urinations) performed by 78 individuals including 8 stallions. Stallions investigated 248 eliminations and overmarked 124. The rate of overmarking by stallions was higher than those of all other sex and age categories. Stallions of all species overmarked all age and sex categories, except Grévy’s zebra stallions did not overmark foal eliminations. In contrast to our first hypothesis, when attracted to the elimination, stallions overmarked non-oestrus females more often than oestrus ones. Thus, our results did not support the hypothesis that overmarking by males has a sexual selection function, but it could be explained by the group cohesion hypothesis. Based on our results, it seems that overmarking by equid males plays a greater role in intra-specific communication than in intra-sexual competition. In addition, this behaviour might play different roles in different species based on their social organisation.
Overmarking is ubiquitous among terrestrial mammals; however, the function of this behaviour has not been fully explained. In addition, previous studies came to differing conclusions. In this study, we tested two hypotheses possibly explaining overmarking by adult males in three equid species. We found that adult males overmarked at a much higher rate than individuals of all other sex and age categories. In contrast to many other studies, our results did not support the hypothesis that overmarking by males has a sexual selection function, but it could be explained by a group cohesion hypothesis.
KeywordsCompetition Defecation Equus Marking behaviour Olfactory communication Scent marking
The authors gratefully acknowledge the assistance of the Zoological Garden staff at Dvůr Králové, Brno, Liberec, Ostrava, and Ústí nad Labem, in particular Luděk Čulík, Markéta Čulíková, Aleš Kopecký, Jiří Soumar, Miroslava Kubelková, Miroslava Doležalová, Pavel Moucha, Radek Hlávka, Lubomír Melichar, Jiří Vítek, Petra Padalíková, Pavel Král, Jaroslav Novák, Rostislav Střižík, Eva Zajoncová, and Lenka Málcová. We thank Radka Šárová, Luděk Bartoš, and Jitka Bartošová for their helpful comments on the earlier draft of the manuscript. The manuscript was highly improved by comments of four anonymous reviewers.
This work was supported by the Ministry of Agriculture of the Czech Republic (MZE-RO0719) and by grant no. 2011/008 of the Student Grant Agency of the University of South Bohemia.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and institutional guidelines for the care and use of animals were followed. This research was carried out in line with all legislation of European Union and the Czech Republic. We received all appropriate permissions from the zoo authorities where the observations were performed. As this was an observational study with no manipulation or disturbance of the animals no animal care and use protocols were required.
- Brown RE, Macdonald DW (1985) Social odours in mammals, vol 2. Clarendon Press, OxfordGoogle Scholar
- Ginsberg JR (1989) The ecology of female behaviour and male reproductive success in the Grevy’s zebra, Equus grevyi. Sym Zool S 61:89–110Google Scholar
- Klingel H (1974) Soziale Organisation und Verhalten des Grevy-Zebras (Equus grevyi). Z Tierpsychol 36:36–70Google Scholar
- Klingel H (1975) A comparison of the social behaviour of the Equidae. International Symposium on The Behaviour of Ungulates and its relation to management. IUCN, Gland, pp 124–132Google Scholar
- Klingel H (2013) Equus quagga plains zebra. In: Kingdon J, Hoffmann M (eds) Mammals of Africa, vol. V: Carnivores, pangolins, equids and rhinoceros. Bloomsbury, London, pp 428–437Google Scholar
- Kruuk H (1995) Wild otters: predation and populations. Oxford University Press, OxfordGoogle Scholar
- Moehlman PD (1985) The odd-toed ungulates: order Perrissodactyla. In: Brown RE, Macdonald DW (eds) Social odours in mammals, vol 2. Clarendon Press, Oxford, pp 531–549Google Scholar
- Moehlman PD, Kebede F, Yohannes H (2013) Equus africanus African wild ass. In: Kingdon J, Hoffmann M (eds) Mammals of Africa, vol. V: Carnivores, pangolins, equids and rhinoceros. Bloomsbury, London, pp 422–428Google Scholar
- Ödberg FO (1971) An interpretation of pawing by the horse (Equus caballus Linnaeus), displacement activity and original functions. Säugetierkd Mitt 10:1–12Google Scholar
- Penzhorn B (2013) Equus zebra Mountain zebra. In: Kingdon J, Hoffmann M (eds) Mammals of Africa, vol. V: Carnivores, pangolins, equids and rhinoceros. Bloomsbury, London, pp 438–443Google Scholar
- Penzhorn BL (1979) Social organisation of the Cape Mountain zebra Equus z. zebra in the Mountain Zebra National Park. Koedoe 22:115-156Google Scholar
- Schilder MBH (1992) Stability and dynamics of group composition in a herd of captive plains zebra. Ethology 90:145–154Google Scholar