Energy metabolism in an obligate frugivore, the superb fruit-dove (Ptilinopus superbus)

Abstract

Ptilinopus superbus (body mass 120.4 5.2 g) is a highly specialised, migratory avian frugivore that is widespread in the rainforests of the Indo-Pacific Region and north-eastern Australia. The effect of the specialised diet on metabolic rate (MR) and body temperature (T_b) were investigated at ambient temperatures (T_a) of 13-30ºC in activity (α) and rest (ρ) phases. At thermoneutrality (T_a = 26ºC), the basal metabolic rate (BMR) was 23.2 4.49 J g^-1 h^-1 , which corresponds closely to the predicted value (22.6 J g^-1 h^-1). Wet thermal conductance (C_wet) was 2.39 0.45 J g^-1 h^-1 ºC^-1 in α and 1.75 0.13 J g^-1 h^-1 ºC^-1 in ρ for T_a between 13 and 21ºC. These conductances are higher than expected (α: 1.87 J g^-1 h^-1 ºC^-1; ρ: 1.16 J g^-1 h^-1 ºC^-1) for a non-passerine bird of this body mass (M), indicating poor insulation of this tropical species. T_b was 39.6 0.76ºC in α and 38.1 0.55ºC in ρ in the observed T_a range, corresponding closely to expected values (40.9 1.35 in α and 38.6 0.66 in ρ). This study shows no evidence of an influence of the fruit diet on the metabolic physiology of superb fruit doves. Analysis of BMR data for all pigeon species sampled so far provides no evidence that a low basal metabolic rate is a general characteristic of the Columbidae.