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Removal experiments indicate that subordinate stallions are not helpers


Linklater, WL and Cameron, EZ and Stafford, KJ and Minot, EO, Removal experiments indicate that subordinate stallions are not helpers, Behavioural Processes: An International Journal of Comparative and Physiological Ethology, 94 pp. 1-4. ISSN 0376-6357 (2013) [Refereed Article]

Copyright Statement

Copyright 2013 Elsevier B.V.

DOI: doi:10.1016/j.beproc.2013.02.005


Relationships between males defending the same harem are described as cooperative or competitive and explained by mutualism, reciprocal altruism, and reproductive concessions or limited control between unequal contestants. These alternate hypotheses can be tested by removing males from harems. Some feral horse (Equus caballus) harems are defended by more than one and up to five stallions. We temporarily removed the subordinate stallion from two of six multi-stallion bands (a harem and its stallions) for three weeks during the breeding season. We monitored harems for changes in composition, and measured and compared rates of (i) intra- and inter-band stallion aggression, (ii) stallion aggression towards mares, and (iii) stallion-mare proximity before subordinate stallion removal and after his return with rates during his absence. Harems were successfully defended during the subordinate's absence and stallion-mare aggression was substantially reduced. Dominant stallions did not require assistance in harem defence, and heightened harassment of mares is directly attributable to subordinate stallion's residence, not characteristics of the dominant stallion or mares. Cooperative hypotheses do not appear to explain multi-stallion bands but the experiments in this study should be replicated further. The limited control hypothesis (e.g., mate-parasitism) appears better supported but we outline its limitations too.

Item Details

Item Type:Refereed Article
Keywords:cooperation, sexual harassment, reproductive concession, optimal skewe Equus caballus, equid
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Behavioural ecology
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Terrestrial biodiversity
UTAS Author:Cameron, EZ (Professor Elissa Cameron)
ID Code:84101
Year Published:2013
Web of Science® Times Cited:4
Deposited By:Zoology
Deposited On:2013-04-17
Last Modified:2017-10-31

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