Thermoregulation in Antarctic fulmarine petrels.
We measured resting metabolic rates at air temperatures between ca. -5 and 30 degrees C in snow petrels (Pagodroma nivea), cape petrels (Daption capense), Antarctic petrels (Thalassoica antarctica), and Antarctic fulmars (Fulmarus glacialoides). We measured seven age classes for each species: adults, and nestlings that were 3, 8, 15, 28, 35, and 42 days old. Basal metabolic rate (BMR) and thermal conductance (C) of adults averaged, respectively, 140% and 100% of values predicted allometrically for nonpasserine birds. Minimum metabolic rates of unfasted nestlings aged 15-42 days averaged, respectively, 97% and 98% of predicted adult BMR in Antarctic petrels and snow petrels, versus 119% and 126% of predicted in Antarctic fulmars and cape petrels. Nestlings of the southerly breeding snow petrel and Antarctic petrel were relatively well insulated compared with nestlings of other high-latitude seabirds. Adult lower critical temperature (T1c) was inversely related to body mass and averaged 9 degrees C lower than predicted allometrically. As nestlings grew, their T1c decreased with increasing body mass from ca. 14 to 22 degrees C (depending upon species) at 3 days of age, to -4 to 8 degrees C when nestlings attained peak mass. Nestling T1c subsequently increased as body mass decreased during pre-fledging weight recession. Nestling T1c was close to mean air temperature from the end of brooding until fledging in the three surface nesting species.
Weathers
W W
WW
Department of Animal Science, University of California, Davis 95616-8532, USA. wwweathers@ucdavis.edu
Gerhart
K L
KL
Hodum
P J
PJ
D000375:Aging; D000818:Animals; D000864:Antarctic Regions; D001481:Basal Metabolism; D001717:Birds / Q000254:growth & development / Q000502:physiology*; D001831:Body Temperature; D001833:Body Temperature Regulation; D001835:Body Weight; D013045:Species Specificity