LIFE-SPAN IN BIRDS AND THE AGING THEORY OF ABSOLUTE METABOLIC SCOPE

1. Maximum lifespan A (in years) in birds can be described by the foll owing allometric exponential functions (W = body mass in g): wild bird s A(w) = 4.75 x W0.17 (N = 821); captive birds A(c) = 5.1 x W0.23 (N = 131). 2. The orders Lariformes, Accipitriformes, Psittaciformes and S trigiformes have physiological life spans clearly above the expected v alues. The orders Galliformes and Piciformes lay clearly below the exp ected range. 3. Different physiological times T(p) show allometric cor relations (N = 91) with a mean mass-exponent of 0.25; mean metabolic r ate M over a broad range of systematic taxa (N = 146), on the other ha nd, correlates with body mass with an exponent of -0.25. 4. The produc t of T(p) x M is a mass-independent (W0) constant value, supporting th e theory of an absolute metabolic scope during the life cycle.