METABOLIC-RATE AND BODY-TEMPERATURE OF AN AFRICAN SUNBIRD, NECTARINIA-CHALYBEA - DAILY RHYTHM AND THE EFFECT OF AMBIENT-TEMPERATURE

Citation
B. Leon et Sw. Nicolson, METABOLIC-RATE AND BODY-TEMPERATURE OF AN AFRICAN SUNBIRD, NECTARINIA-CHALYBEA - DAILY RHYTHM AND THE EFFECT OF AMBIENT-TEMPERATURE, South African journal of zoology, 32(2), 1997, pp. 31-36
Citations number
29
Categorie Soggetti
Zoology
ISSN journal
02541858
Volume
32
Issue
2
Year of publication
1997
Pages
31 - 36
Database
ISI
SICI code
0254-1858(1997)32:2<31:MABOAA>2.0.ZU;2-1
Abstract
The oxygen consumption ((V) over dot O-2) of the lesser double-collare d sunbird, Nectarinia chalybea, was measured at ambient temperatures ( Ta) from 7 to 35 degrees C. The diel variation in body temperature (Tb ) and wet thermal conductance (C) was also determined. The sunbirds (m ean mass 8.36 g +/- S.E. 0.21 g) showed a pronounced diet cycle of (V) over dot O-2, with a mean reduction of 50% at night. Basal metabolic rate was estimated to be 3.23 mi O-2/g.h, which is 88% of the predicte d value for a passerine bird of this size. There was a mean reduction in Tb of 3.6 degrees C at night. Both day and night values of Tb decre ased with decreasing Ta, as did individual values of C. Winter breedin g in the south-west Cape is energetically stressful for lesser double- collared sunbirds, but they have the physiological capacity to reduce their energy expenditure substantially at night.