weights basal metabolic rate per unit weight mice greater rabbits ref name hillisetal ac physical activity also increase animal 's metabolic rate animal runs metabolic rate increases linearly speed ref name hillisetal ac however relationship non linear animals swim fly fish swims faster encounters greater water resistance metabolic rates increases exponential ref name hillisetal ac alternatively relationship flight speeds metabolic rates u shaped birds ref name hillisetal ac low flight speeds bird must maintain high metabolic rates remain airborne
Natural science Biology