How do birds get ready for migration?
A. The key component in this process is shorter days at the end of summer. There are photoreceptors in a bird’s brain that trigger hormonal changes. One hormonal change causes many birds to molt at the end of summer. The new feathers will stand up better to the challenges of long flight. Another hormonal change triggers a huge appetite. Birds eat voraciously and gain weight. Many insect-eating birds will supplement their diets at this time of year with fruits, grains, etc. that can be converted to body fat, which birds burn effciently for energy. All these hormonal changes make birds restless. Then, one day, when the winds are favorable, it’s time to head south!
