Circadian Metabolic Responses to Food Deprivation in the Black-Shouldered Kite

Abstract

Circadian metabolic responses to food deprivation were measured in Black-shouldered Kites (Elanus caeruleus) at thermoneutral and cold ambient temperatures. The basal metabolic rate (BMR) of the kites was 60-70% of that predicted by various allometric equations. They displayed marked circadian rhythms of BMR and body temperature (T b ), but did not show any indication of metabolic depression or adaptive hypothermia in response to food deprivation. Instead, moderate reductions in metabolic rate and T b were observed, resulting in significant reductions in the daily energy expenditure. The conservative metabolic traits shown by the kites and their responses to food deprivation suggest tolerance of periodic, limited food supplies.