Removal experiments indicate that subordinate stallions are not helpers.
Abstract: 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.
Copyright © 2013 Elsevier B.V. All rights reserved.
Publication Date: 2013-02-18 PubMed ID: 23428706DOI: 10.1016/j.beproc.2013.02.005Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This research study explores the role of subordinate stallions within groups of wild horses known as harems. The study found that the presence of these subordinate stallions significantly increased aggressive interactions among other stallions and towards mares, and that the dominant stallion was able to successfully protect the harem without assistance from the subordinate stallion.
Research Methods and Objectives
- The research aimed to investigate interactions between male horses in a harem, specifically focusing on the interaction between subordinate and dominant stallions. This was done to understand if the presence of subordinate stallions is necessary for the survival of the harem, or if they contribute to an increase in aggression.
- The researchers conducted an experimental study on six multi-stallion bands. They removed the subordinate stallion from two of these groups for three weeks during the breeding season and monitored the behavior of the remaining stallions and mares.
- Specific behaviors were monitored and their frequency was compared before the removal, during the subordinate’s absence, and upon his return. This included rates of intra- and inter-band stallion aggression, aggression towards mares, and the proximity between stallions and mares.
Key Findings
- The study found that the dominant stallion was able to successfully defend the harem in the absence of the subordinate stallion, indicating that the subordinates are not necessarily needed for harem defense.
- Furthermore, rates of aggression towards mares were substantially decreased during the absence of the subordinate stallion. This suggests that much of the heightened harassment of mares can be directly attributed to the presence of the subordinate, and not the dominant stallion or the mares themselves.
- Thus, the researchers concluded that the presumed cooperation between multiple stallions in a harem, as suggested by some theories, may not hold true. Subordinate stallions may play a more antagonistic role within a harem.
Implications and Further Research
- Based on these findings, the researchers suggested a different hypothesis that aligns better with their findings: mate-parasitism. In this scenario, subordinate stallions may not be involved in harem defense but may interfere and cause disruptions to increase their chances of mating.
- The study emphasized the need for further, more extensive research, to further test and validate its findings.
Cite This Article
APA
Linklater WL, Cameron EZ, Stafford KJ, Minot EO.
(2013).
Removal experiments indicate that subordinate stallions are not helpers.
Behav Processes, 94, 1-4.
https://doi.org/10.1016/j.beproc.2013.02.005 Publication
Researcher Affiliations
- Ecology Group, Institute of Natural Resources, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand. wayne.linklater@vuw.ac.nz
MeSH Terms
- Analysis of Variance
- Animals
- Female
- Horses
- Male
- Sexual Behavior, Animal
- Social Behavior
- Statistics, Nonparametric
Citations
This article has been cited 2 times.- Górecka-Bruzda A, Jaworska J, Stanley CR. The Social and Reproductive Challenges Faced by Free-Roaming Horse (Equus caballus) Stallions. Animals (Basel) 2023 Mar 24;13(7).
- Bowyer RT, McCullough DR, Rachlow JL, Ciuti S, Whiting JC. Evolution of ungulate mating systems: Integrating social and environmental factors. Ecol Evol 2020 Jun;10(11):5160-5178.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
