What We Have Learned

Relatedness & Health

Relatedness: Genetics

  • Tissue samples have been collected from more than 200 unique individuals in preparation for creating a family tree among the alligators.
  • A relatedness analysis has been conducted on individuals captured at the Okefenokee Swamp Park resulting in several interesting findings!

  • The previous dominant male, Oscar, whose skeleton can be seen on display in the Gift Shop, was not found to be related to many alligators still living at the Swamp Park.

    • Many believed Oscar was the grandfather to most of the alligators residing at the Swamp Park, but Oscar was only strongly related to one individual, a small adult female.

    • We hypothesize that when a new dominant male takes over a territory, he rids the area of males related to the previous dominant male. This would increase the survival rate for offspring of the new dominant male as there would be fewer potential predators and less competition.

  • We were able to determine parentage for three nests found at the Swamp Park. All three nests were all at least partially sired by the dominant male. This indicates that dominance plays a role in which individuals are able reproduce.

  • We found one instance of multiple paternity, or the occurrence of one nest having two different fathers.

  • We were able to combine the relatedness analysis with the satellite tags to compare the effect that relatedness has on territory overlap.

    • Animals that were not related were more likely to have overlapping territories than related individuals.

Click images to enlarge

Health: Diet

  • Alligators are opportunistic feeders and might try to ingest anything that moves. 
    • Ex. More insects and small prey observed in large animals than was expected.
  • Availability of prey varies between habitats and season.
    • Ex. Alligators in the swamp may focus more on hunting birds, fish, reptiles, and amphibians while coastal alligators may enjoy marsh species like blue crab and shrimp.
    • Ex. Some alligators learn to specialize on a prey item, like dragonfly larvae, snails, frogs, or minnows based on when these items are abundant. 
  • Digestive rates of prey items varies greatly, and stomach contents are just a snapshot of what an alligator has actually been eating all year.
    • Ex. Just because your stomach might have a cheeseburger or pancakes in it, doesn’t mean that’s the only thing you eat Winky Face

Click images to enlarge

Health: Ecotoxicology

  • Generally, there is a positive relationship between mercury level and length of an alligator.
    • In most cases, the longer the alligator the more mercury it has in its body. Additionally, mercury accumulates in alligators with age, a pattern that is generally true with other large vertebrates, including people. However, this is also based on feeding patterns, and an older animal with more fat stores can show gradual decreases in mercury with age.
  • In the Okefenokee, the relationship is more correlated among juveniles compared to other habitat types.
    • This trend is most reliable in younger alligators, after they reach a certain size the correlation between length and mercury levels becomes more variable as it is dependent on feeding habits.
  •  We know that heavy metal accumulation can be bad for the health of organisms, but most reptiles seems to handle higher loads better than mammals (humans) and birds.

Tail Notches

Tail Notches

Tail notch codes begin with the letter A where the single row of scutes begins.

Tail notch tags

The blue tag is placed in scute A. Scutes BCD are notched.

What are tail notches?

Tail notches are the section of the tail scutes that are removed as seen in the picture on the right. 

Why tail notches?

Tail notches are an effective and humane way to permanently mark an alligator. These scutes will not grow back but other than the initial pain an alligator may feel during removal it will cause no other ill effects.

What is their purpose?

Tail notches serve two purposes 1) it is a way to permanently mark the alligator for long term identification 2) the scutes that are removed will serve as tissue samples for our genetic project.

What’s the blue tag?

The blue tag is an allflex tag that is most commonly used in the ear of cattle. It serves as an easier way to identify the alligator as the tail notches are not always easily seen. The downside of these colored tags is that they can fall off after a few years, which is why we also use tail notches

All photos by University of Georgia Marine Extension and Georgia Sea Grant, unless otherwise noted.