Taxonomy. The average size for an adult female American alligator is 8.2 feet (2.6 m), and the average size for a male is 11.2 feet (3.4 m). Exceptionally large males can reach a weight of nearly half a ton or 1,000 pounds.fter two to three years, they leave that area in search of food, or are driven out by larger alligators. One interesting aspect of alligator biology is that they undergo periods of dormancy when the weather is cold. They excavate a depression called a “gator hole” along a waterway and use it during dormancy.