Hummingbirds Energy Needs and Adaptations

Hummingbirds have a high daily energy requirement for their size compared to other organisms including humans. The average sized human requires 2,000-2,500 kcal/day whereas a 3.5kg hummingbird requires 7.65kcal/day. If humans needed the same average intake as hummingbirds it would require about 800 can of coke in a day to meet the caloric requirements. Hummingbirds have high metabolic rates and various adaptions to make this work. They have a sufficient oxygen delivery system to tissues, rapid conversion of oxygen and nutrients to ATP, a high capacity to transport stored nutrients to fuel, and a digestive capacity to supply uptake of nutrients at sufficient rates. Hummingbirds muscle morphology is also highly adapted to suit their lifestyles. They have high capillary density to support high rates of oxygen delivery along with a high mitochondrial density.