Net energetic gain in sunbird territory defense was:
Territoriality is occupation and exclusive defense of area against conspecifics to secure resources like food, mates or nesting sites, differing from home range which is undefended. Benefits include exclusive resource access, costs involve time and energy for patrolling and aggression. Optimal territory size maximizes net benefit. Defense via song, scent marking, visual displays and aggression maintains boundaries. This behavior illustrates resource defense theory central to behavioral ecology. Hence Positive defines area defense strategy. This concept integrates genetics, ecology and molecular evidence, frequently tested in NEET, GATE and CSIR-NET, highlighting links between genotype, phenotype and environment.
Ref: Krebs & Davies, Behavioural Ecology, Chapter 5: Territoriality.