The problem with shipping by boat is the variability. Your just in time supply chain needs to assume a ~6 weeks or longer in case of a strike etc.   Variability goes down a little when you have more boats going to more ports.<p>As a final point on energy larger birds can do generally have a slower metabolism.  They simply need less energy per lb to maintain flight and can travel longer distances on smaller per pound energy budgets.<p>Not that I think anything could convince you, but look into glide ratios and optimum glide speeds.  If A and B have 15:1 ratios and B glides at 2x the speed that&#x27;s more efficient.