Compared to crocodiles, alligators are not naturally aggressive creatures. Popular convention might make them out as aggressive bloodthirsty fiends, but they are hardly as dangerous as saltwater or Nile crocodiles, which are much larger and much more aggressive. However, on occasion, American alligators can and do attack humans, and they can and do attack each other.
Male alligators are solitary and can be quite territorial. A male alligator of 9 feet can own a territory of about 2 square miles and could also have about 10-15 females in his territory, along with their children. A male alligator of 12-14 feet could have up to 3 square miles and have even more females within his territory. (Source: animalquestions.org). So, when two males are in each other’s “personal space”, they’ll often fight each other in a nasty turf war.
Prior to participating in such fights, the male (and female) alligators will emit low bellowing and hissing sounds to attract mates and ward of rivals. These bellowing and hissing sounds are so low that they cause the water above their backs to sprinkle up like a water fountain. In the video below, you can witness and hear this unusual display. This the primary reason alligators (and other reptilians) are the most vocal of the reptiles.