During the past few weeks the hummingbirds that have been visiting our feeders seem are on a feeding frenzy. The reason for this is they are trying to store enough fuel (in the form of fat) to power their fall migration.
Prior to migration, an adult female ruby-throated weighs roughly 1/10th of an ounce (3.5 grams). These long-distance migrants will consume enough nectar and insects to increase their weight to 5.5 grams (0.194 ounces). Each gram of this stored fat enables a hummingbird to migrate 300 miles.
