by Whit Gibbons

May 11, 2008

Springtime brings out different kinds of animals, which in turn brings forth questions about the animals. The following questions about alligators have come my way recently.

Q. A friend said she heard male alligators bellowing somewhere in southern Georgia during a recent trip. Is this true? Could the noise she heard simply have been bullfrogs?

A. Both alligators and bullfrogs make deep, resonant vocalizations. In the Southeast, both species may be heard from at least late April to mid-May. An adult alligator makes a rumbling sound, much louder than a bullfrog, that you can practically feel if you are standing nearby. I know of a large male alligator (over 12 feet) and a female (less than eight feet) that live in a pond in South Carolina; they have been bellowing for the past several days. My impression is that the female is responding to the male's bellows and that she is actually louder.

The U.S. Fish and Wildlife Service provides audio of bellowing alligators at www.fws.gov/video/sound.htm. You can hear what a bullfrog and other southern frogs and toads sound like on the SREL website at www.uga.edu/srelherp/.

Q. Do baby alligators really call their mothers the way birds do?

A. Most biologists consider birds to be the closest relatives of alligators and crocodiles evolutionarily, and many similarities between the groups are apparent. Not only do baby alligators call their mothers, they start doing so before they even leave the nest. Mother alligators lay their eggs on land inside large mounds they build of dirt and vegetation. At the time of hatching, the babies begin making yelping sounds that attract the mother to the nest. She digs into the nest, opens eggs with her teeth if necessary to let babies free, and will even carry the young to the water in her mouth.

Once in the water, baby alligators stay in the vicinity of their mother and when one feels threatened, it will make gulping or yelping sounds that can be heard several feet away. A mother alligator will defend her nest and young from predators, and will investigate when she hears a baby in distress. She will attack another animal, including a person, who appears to be a threat to her babies.

Q. Do alligators ever leave freshwater lakes and rivers to go onto land or into the ocean?

A. Alligators leave drying freshwater habitats to travel overland during droughts, and males move between bodies of water in search of mates during the spring and to avoid confrontations with larger male alligators. Alligators will enter saltwater habitats on occasion and have even been found a mile or more out to sea. They do not live in the ocean but can tolerate saltwater for hours or even days without a problem.

Q. How big do the largest alligators get?

A. Alligators indisputably can reach lengths of more than 13 feet and weigh more than 700 pounds. In a study done in Florida from 1977 to 1993, the largest male alligator reported was 14 feet long, and the largest female was 10 feet, 2 inches. An alligator that was killed and left in a Louisiana marsh in the early 1900s was estimated to be over 19 feet long. However, the Louisiana record has long been disputed, and the largest size verified for an alligator from anywhere, based on a statistical analysis of skulls, skins, and live animals, was slightly less than 15 feet.

Q. Are larger adult alligators more aggressive toward humans than smaller ones?

A. Adult females are smaller than the males and when guarding a nest or babies are often aggressive toward human intruders. They will come up on land with mouth open to chase a person away. Male alligators are aggressive toward smaller males during the mating season and perhaps other times, but I have never seen one be aggressive toward a person. Aside from parental protection by females, attacks on humans generally involve situations in which alligators have been fed by people and thus have developed atypical behavior.

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