A7 Migratory Stress

Title

A7 models the energy dynamics of a bird during a long migratory stage, from the beginning with full reserves to exhaustion. It is the only A-series model that describes a progressive time path rather than a one-time perturbation: the state of the system changes continuously as fat reserves are consumed. The central physics is the positive feedback between mass and flight cost: as the bird becomes thinner, P_induced falls (lower weight), which extends potential range; but if the reserves are exhausted before reaching the destination, the bird begins protein catabolism, simultaneously degrading its muscles (coupling with A4) and reducing available P_max. The model defines three phases: lipid phase (fat fuel, RQ 0.71, optimal performance), mixed phase (fat + protein), and critical phase (mass below the minimum viable threshold, imminent mortality). It allows you to calculate the theoretical maximum range and the energy safety margin for a given species and starting condition.

ID:4217