Bruce, a kea missing his entire upper beak, became undefeated alpha male by innovating a novel lower-beak jousting technique no intact kea replicates.
Key Takeaways
Bruce won all 36 of his male-male interactions across 227 recorded agonistic events, ranking first by David’s score among 9 males.
His jousting technique targets a wider range of body parts (back, head, wings, legs) than typical downward neck bites, displacing opponents 73% of the time vs 48% for kicks.
As alpha, Bruce showed the lowest faecal glucocorticoid metabolites in the group – the first evidence linking dominance to stress physiology in kea.
Up-hierarchy allopreening: subordinate males, especially the lowest-ranked, groomed Bruce’s exposed lower beak to remove debris, likely contributing to his low stress hormones.
Unlike the only two comparable cases (a polio-affected chimp, an aging macaque), Bruce achieved alpha status without allies or coalition networks.