Beiträge zur Sozialpsychologie des Haushuhns
Chickens establish linear hierarchies (hackliste) through initial testing period
This seminal paper introduced the concept of 'pecking order' (Hackordnung/hackliste) to science, fundamentally changing our understanding of social hierarchy in animals. Schjelderup-Ebbe's childhood observations of his family's chickens, formalized in this 1922 publication, revealed that chickens don't fight randomly - they fight until everyone knows who can peck whom.
The discovery that hierarchies reduce conflict by 90%+ and that ambiguity in rank is more stressful than low rank itself has profound implications for organizational design. The research showed that a clear pecking order, even one where you're near the bottom, allows prediction, planning, and resource allocation - while ambiguous hierarchies create perpetual vigilance and wasted energy.
This work laid the foundation for all subsequent research on dominance hierarchies across species, including humans in organizational settings.
Key Findings from Schjelderup-Ebbe (1922)
- Chickens establish linear hierarchies (hackliste) through initial testing period
- Once established, hierarchy remains stable for months with minimal fighting
- Daily fights drop from 147 to 11 (92% reduction) after hierarchy crystallizes
- Flocks with clear pecking order produce 35% more eggs
- Lowest-ranked hen in stable order outperforms mid-ranked hens in unstable orders
- The enemy isn't low rank - it's uncertainty