As autumn progresses, millions of birds disperse to the reaches of the globe to find the food they need to survive. In addition to triggering atmospheric changes, shortening days cause physiological and behavioral changes in the birds. To prepare for migration, birds literally gorge themselves. Fat fuels their flight. Flying requires incredible amounts of energy.
Sufficient fat minimizes the number of stopovers, where birds are vulnerable to predation.
Stored fat also prevents starvation if a storm blows the migration off course. Flight and Flocks Flight is a marvel of nature. It is a complex and delicate balance. A number of adaptations combine to provide the perfect combination of power and lightness. Hollow bones, air sacs, aerodynamic body shapes, powerful flight muscles and feathers coordinate to carry birds above the earth.