SPACING & SOCIAL SYSTEMS

Social System Components

Spacing, mating system, and social organization.

Home Range

Area used for daily activity; not actively defended.

Territory

Defended area with exclusive access to resources and mates.

Economic Defensibility

Territoriality evolves when benefits of defense outweigh costs.

Golden-Winged Sunbird Example

Defend nectar sources only when moderately abundant—maximize energy efficiency.

Factors Affecting Territoriality

1) Abundance 2) Distribution 3) Renewability of resources.

Resource Abundance

Too low or too high = not worth defending.

Clumped Resources

Encourage territory defense if predictable and renewable.

Territory Types

Classical (all-purpose), Nesting-only, Feeding-only, Mating-only (leks).

Lek Behavior

Males display competitively; females choose mates; optimal group size ≈ six males.

Lekking Species

Grouse, ruff sandpipers, fallow deer, stalk-eyed flies.

Social Organization Forms

Solitary, pair, family, dominance hierarchy, harem, aggregation.

Human Territoriality

Homes and personal spaces act as territories; cultural behaviors (permission, gifts) reflect evolved spacing instincts.