Seasonal metabolic variation over two years in an Afrotropical passerine bird.
Seasonal trends in metabolic parameters are well established in avian populations from highly seasonal environments, however, seasonal trends in metabolism of birds from lower latitudes (and of Afrotropical birds in particular) are not well understood. We investigated seasonal trends in metabolism for a small (10-12g) Afrotropical bird, the Cape White-eye (Zosterops virens), using flow-through respirometry in two summers and two winters. There was no seasonal difference in body mass between consecutive seasons. The lower critical limit of thermoneutrality was lower in winter (23°C) than in summer (28°C), as expected for a small Afrotropical bird. In the first year of the study, mean whole animal basal metabolic rate (BMR) of Cape White-eyes was significantly lower in winter than in summer, while in the second year of the study this trend was reversed, and in the middle two seasons there was no significant difference in BMR. Differences in mean temperature and mean rainfall between seasons could not account for the seasonal trends in BMR. We conclude that seasonal trends in avian BMR may vary between years, within a population.
School of Life Sciences, University of KwaZulu-Natal, P Bag X01, Scottsville 3201, South Africa. Electronic address: lindojano@yahoo.com.
Lindy J
LJ
Thompson
School of Life Sciences, University of KwaZulu-Natal, P Bag X01, Scottsville 3201, South Africa.
Mark
M
Brown
School of Life Sciences, University of KwaZulu-Natal, P Bag X01, Scottsville 3201, South Africa. Electronic address: downs@ukzn.ac.za.
Colleen T
CT
Downs
D000064:Acclimatization; D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D004777:Environment; D005260:Female; D005843:Geography; D008297:Male; D046109:Passeriformes / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D011891:Rain; D012621:Seasons; D013019:South Africa; D014870:Water Loss, Insensible / Q000502:physiology
Afrotropical; Basal metabolic rate; Cape White-eye; Seasonal variation; Zosterops virens