Measurements of metabolic rate and fat deposition were made on a three-species hummingbird guild in southeastern Arizona to determine if the energetic advantage gained by a dominant territorial species (Lampornis clemenciae) over subordinate competitors (Archilochus alexandri and Eugenes fulgens) resulted in less frequent use of torpor. Results showed that L. clemenciae was able to store enough fat during the day to avoid nocturnal torpor. Restricted access to food limited fat storage in both competitors, resulting in frequent torpor use. Avoidance of torpor by L. clemenciae supports the notion that use of nocturnal torpor by hummingbirds comes with a cost, and that the ability to avoid torpor is an important benefit to dominant species.
Powers, Donald R., "The Impact of Social Interactions on Torpor Use in Hummingbirds" (2004). Faculty Publications - Department of Biological & Molecular Science. 70.
Originally published in Life in the Cold: Evolution, Mechanisms, Adaptation, and Application. Twelfth International Hibernation Symposium (Barns, B. M, and Carey, H. V. eds.). Biological Papers of the University of Alaska, number 27. Fairbanks, AK, USA: Institute of Arctic Biology, University of Alaska.