Long-tailed Widowbird

Male long-tailed widowbirds sport tail feathers reaching 50 centimeters - half a meter of black plumage trailing behind a bird whose body measures just 15 centimeters. These tails create substantial flight drag, increase predation risk, and require significant protein investment to grow annually. Yet females consistently prefer males with longer tails.

Malte Andersson's famous 1982 experiment proved the causal relationship: he artificially lengthened some males' tails by gluing on extra feathers and shortened others. Males with experimentally elongated tails attracted four times more mates than shortened-tail males, despite being identical in every other respect. The experiment demonstrated that female preference, not male survival, drives tail evolution.

This maps to brand extension strategies where companies stretch their most attractive features beyond functional optimum. A luxury brand might extend into increasingly impractical product categories - not because these products serve customer needs, but because they signal brand prestige. The widowbird's tail is impractical by design; its impracticality is the point.

The widowbird also illustrates the competitive dynamics of conspicuous features. In populations, average tail length increases over generations as females' preferences and males' tails co-evolve. For businesses, this suggests that in markets where signaling matters, feature escalation becomes self-perpetuating. Each competitor's signal investment raises the bar for everyone else, creating an arms race with no natural stopping point except resource exhaustion.