Golden-winged Sunbird
African birds that defend flower patches for nectar, demonstrating the resource-defense threshold with mathematical precision.
African birds that defend flower patches for nectar, demonstrating the resource-defense threshold with mathematical precision. Researcher Gill tracked 47 sunbirds over 3 years across different flower densities.
High-density flowers (>100/acre): 0.5-acre territory, 24 patrols/day, 1,800 calories spent, 2,400 calories gained = +33% surplus, territory vigorously defended. Medium-density (30-100/acre): 1.2-acre territory, 12 patrols/day, 1,400 calories spent, 1,500 calories gained = +7% surplus, territory weakly defended. Low-density (<30/acre): Territory would require >3 acres with impossible patrol frequency, defensive costs exceed possible benefits, result is no territory - nomadic feeding instead.
Notable Traits of Golden-winged Sunbird
- Defends territory only when math works
- Abandons territoriality entirely when resource density drops below threshold
- Demonstrates that optimal strategy adapts to environment