Revista Chilena de Historia Natural 78 (2): 281-294, 2005
RESEARCH ARTICLE
Dietary protein and carbohydrate affect feeding behavior and metabolic regulation in
hummingbirds (Melanotrochilus fuscus)
The objective of this work was to link hummingbird feeding behavior with metabolic
regulation and in addition to assess whether dietary composition would affect entrance into torpor. Hummingbirds were fed a
combination of diets with contrasting amounts of protein and carbohydrate. The diets were composed of the following: 2.4 % protein
(P) – 12 % sucrose (S) and 0.8 % protein (P) – 36 % sucrose (S). The main findings showed that periods of feeding on each of the
diets could be distinguished as separate bouts or feeding events. Hummingbirds presented to high protein-low carbohydrate diets
(2.4P-12S) ingested a larger volume of diet, fed for longer (both around 1.7x) and increased the interval between feedings compared
with hummingbirds fed diets 0.8P- 36S. Physiological regulation between feeding events, on the other hand, was achieved through an
increase in metabolic rate for low protein-high sugar diets (0.8P-36S). This response could probably be related to high sucrose
assimilation rates through the digestive system of hummingbirds, a process already known to be very efficient in these birds.
Additionally, there was a steeper decrease in oxygen consumption for hummingbirds fed diets 2.4P-12S during fasting and a
suggestion of a higher torpor incidence in birds fed these diets.
Key words:
hummingbird feeding,
carbohydrate and protein interaction, unbalanced diet, feeding behavior, torpor
