Metabolic and thermal physiology of pigeons and doves

Abstract

Pigeons and doves (Columbidae) are an interesting group to examine for physiological adaptations to climate and diet because this cosmopolitan family comprises more than 300 species that are mostly granivores, although some are specialized frugivores. We determined allometric and phylogenetic effects on body temperature (Tb), basal metabolic rate (BMR; J h-1), and wet thermal conductance (Cwet; J h-1 C-1), and we examined mass (M) and phylogenetically corrected residuals for further effects of climate, diet, and landmass size (mainland or island). Independent contrasts, correlograms, autoregression, and phylogenetic eigenvector regression (PVR) were used to examine phylogenetically related effects. We found a small but significant phylogenetic pattern for body mass of columbids. For Tb, there was no significant effect of mass or phylogeny. There was a significant effect of climate on Tb and no significant effects of diet or landmass without mass or phylogenetic correction, but after mass and phylogenetic correction, there were no effects of climate, diet, or landmass. For BMR, there was a strong allometric effect, and residuals were significantly lower for arid and tropical species but not for temperate species, compared to predictions for nonpasserine birds. There was a nearly significant autoregressive phylogenetic relationship for BMR (r = 0.44), and the strong allometry of BMR remained for independent contrasts (slope = 0.731), autoregressive residuals (0.698), and PVR (0.705). Residuals, from regression of autoregression and PVR residuals of M and BMR, were significantly associated with climate: arid pigeons had a lower BMR residual than tropical and temperate pigeons. PVR residuals were significantly affected by landmass (island columbids had a smaller residual than mainland columbids), but autoregression residuals were not. There was no association of autoregression or PVR residuals with diet. For Cwet, there was a strong allometric effect, and residuals for columbids were significantly higher compared to other birds. There was no significant relationship for Cwet of columbids to climate, diet, or landmass. There was no significant autoregressive or PVR relationship for Cwet, and the strong allometry remained after phylogenetic analysis by independent contrasts (slope = 0.501), autoregression (0.509), and PVR (0.514). Residuals from autoregression and PVR were not significantly correlated with climate, diet, or landmass (mainland/island).