Low Energy Level
Birds that fly have several adaptations that humans and other animals do not have. The first of the traits is a keeled breastbone. The breastbone formation allows the bird to use its wings without feeling a pull in the breastbone area. It is necessary to make the entire body structure stronger.
Birds also have numerous hollow or porous bones if you will. The hollowness of the bones is designed for a better circulation system during flight. The bird needs a closed circulation system in which blood can flow with ease. Many of the hollow bones are also a part of the respiratory system. This leads to the third and last trait that was adapted for birds that fly.
The air sacs which supply oxygen were another adaptation. In order to get enough air at altitude the bird had to adapt. This meant allowing for hollow bones for respiration, as well as blood travel since oxygen is also transported through blood. The airs-sacs help retain enough oxygen so that the bird can breathe at higher altitudes without any sort of breathing apparatus. For humans, our lungs would require a pressurization of air in order to breathe at higher altitudes. It is why in diving we also need to have scuba tanks with proper air because the pressure changes. In a bird the air sacs allow for this change.
While it may seem that a low energy level would be something needed when you first read the question it is definitely not. A bird needs to be able to have high energy to fly long distances. Instead, what they need is the use of low energy so that their high energy stores will last during flight.
Birds that fly have several adaptations that humans and other animals do not have. The first of the traits is a keeled breastbone. The breastbone formation allows the bird to use its wings without feeling a pull in the breastbone area. It is necessary to make the entire body structure stronger.
Birds also have numerous hollow or porous bones if you will. The hollowness of the bones is designed for a better circulation system during flight. The bird needs a closed circulation system in which blood can flow with ease. Many of the hollow bones are also a part of the respiratory system. This leads to the third and last trait that was adapted for birds that fly.
The air sacs which supply oxygen were another adaptation. In order to get enough air at altitude the bird had to adapt. This meant allowing for hollow bones for respiration, as well as blood travel since oxygen is also transported through blood. The airs-sacs help retain enough oxygen so that the bird can breathe at higher altitudes without any sort of breathing apparatus. For humans, our lungs would require a pressurization of air in order to breathe at higher altitudes. It is why in diving we also need to have scuba tanks with proper air because the pressure changes. In a bird the air sacs allow for this change.
While it may seem that a low energy level would be something needed when you first read the question it is definitely not. A bird needs to be able to have high energy to fly long distances. Instead, what they need is the use of low energy so that their high energy stores will last during flight.