There are two types of atomic bonds-ionic bonds and covalent bonds. They differ in their structure and properties. Covalent bonds consist of pairs of electrons shared by two atoms, and bind the atoms in a fixed orientation. Relatively high energies are required to break them (50â-â200 kcal/mol).
Hummingbirds fly by day when nectar sources such as flowers are more abundant. Flying low allows the birds to see, and stop at, food supplies along the way. They are also experts at using tail winds to help reach their destination faster and by consuming less energy and body fat. Research indicates a hummingbird can travel as much as 23 miles in one day.
A hummingbird is the only bird able to fly backwards (under its control). It is not aerodynamically possible for most birds to fly backwards. However, some are able to turn somersaults or cartwheels in mid-air, as a means of better pursuing or catching their prey. One example of this is the Roller Pigeon, which uses the technique to catch insects in flight.