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Social hierarchy determination in rams: A comparison of different methods
1Departamento de Biociencias, Facultad de Veterinaria, Ruta 8 km 18, Montevideo 13000, Uruguay.
Behavioural Processes
|January 7, 2026
Summary
Dominance index (DI) calculations varied by method, but hierarchical positions showed concordance across food competition, estrus female competition, and spontaneous agonistic interactions (AI) in rams. DI values did not consistently predict rank.
Area of Science:
- Animal behavior
- Ethology
- Social dominance
Background:
- Understanding social hierarchy is crucial in animal behavior studies.
- Dominance index (DI) calculation methods can influence results.
- Assessing hierarchy stability across different interaction types is important.
Purpose of the Study:
- To examine the relationship between dominance index (DI) calculation methods (absolute vs. relative).
- To compare DI values derived from spontaneous agonistic interactions (AI).
- To determine the concordance of hierarchical positions across food competition, estrus female competition, and spontaneous AI.
Main Methods:
- Calculated DI using absolute and relative values for food competition, estrus female competition, and spontaneous AI.
- Observed 12 rams in controlled social settings.
- Assessed individual hierarchical positions based on interaction outcomes.
Main Results:
- Positive correlation found between absolute and relative DI measures across all tested methods.
- No significant correlation between DI values from food competition and estrus female competition, or spontaneous AI.
- High concordance observed in hierarchical positions derived from food competition, estrus female competition, and spontaneous AI.
Conclusions:
- While DI calculation methods yield different values, they reflect a consistent hierarchy.
- Spontaneous agonistic interactions provide a reliable indicator of social rank in rams.
- DI values alone may not fully predict an individual's precise hierarchical position.
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