🐦 Warbler Flyway Lab: Stopover Refuelling, Fuel Load, Tailwind and the Time- versus Energy-Minimising Migrant

Two small migrants cross a stylised flyway from boreal forest over a sea and a desert to the Sahel. Each decides how fat to get at every stopover; a dynamic-programming optimiser finds the fastest and the most fuel-frugal plan from Breguet-type flight-range physics, refuelling rates and tailwinds, and shows the time-versus-energy trade-off.