Red-footed tortoise a thing of mystery

April 2, 2018

Photo: Christopher May 

 

Long-time readers of this Creature Feature may remember the article in January 2015 about baby tortoise, Hercules. Hercules is son to Goliath, the oldest animal at the Pueblo Zoo at 58 years old. Hercules is now 4 years old and thriving in the Pueblo Zoo Discovery Room where he is visible to the public in a roomy new tank.

 

While often referred to by default as male (probably primarily due to his name), we are not completely certain yet of his gender. This is more common than one might think, as the gender of many animals, especially reptiles and some birds, is not always physically obvious, especially not until later development.

 

In mammals, genitalia is usually displayed externally, so it is a bit easier to tell the sex -- though in the case of smaller animals and those that stick close to mom, it may be hard to get a glimpse of anything of significance until later on.

 

In the case of reptiles and some birds, the genitalia may not be visible at all, making it harder to tell the sex without a DNA test or other tricks of the trade. Many in the animal kingdom display "sexual dimorphism" which are physical characteristics or behaviors that distinguish gender. (For example, male birds are often more brightly colored than females and their song and movements may be different.)

In some animals, these characteristics may take a while to develop, as is the case with our young Hercules. Male tortoises usually start to develop a curve in their bottom shell (plastron) as they grow, which is helpful in the logistics of mating when the male climbs on top of a female's shell. We expect that we may see this type of development in Hercules in the next year or so.

 

People who work with specific types of animals a lot may have "tricks" to help them guess at sex determination. However, complete accuracy is often not possible without further growth and development, or even a specific blood test. This is why in our history at the zoo we have had a male bull snake named Doris, a male penguin named Mona, and a male eagle named Keisha.

 

Our most current mystery involves another Goliath -- of the feathered type. Our hyacinth macaws, Goliath and Delilah, seem to be laying twice as many eggs as normal, with none of them getting fertilized. Our keepers are suspecting that the two birds have more in common than we thought. Only a test will tell now.

 

Just the facts

 

Scientific name: Geochelone carbonari

Common name: Red-footed tortoise. They are called "red-footed" because of the red spots that are located on their legs and head.

 

Description: Red-footed tortoises have a variety of different colorings, depending on their locality. The primary color on the skin is black, with red or orange colored scales on the legs and face. The legs are clubbed at the end, as the red-footed tortoise is terrestrial.

 

The main feature of all turtles and tortoises is their hard shell. The shell is part of the body and cannot be removed, as some people think. Tortoises are able to feel when the shell is touched, much in the same way that we can sense when our fingernails are touched. The spine and ribs run along the inside of the shell. The top part of the shell is called the carapace; the bottom is called the plastron. It grows with the tortoise throughout its life.

 

Male red-footed tortoises can get to be about 14 inches in length, with females getting to be about 12 inches. Each scale (or scute) on the shell is dark around the edges, and brown or tan in color in the center.

 

Red-footed tortoises are omnivores, eating grasses, fruits, flowers, leaves and occasionally insects or carrion.

 

Range: Parts of South America, with the main range being east of the Andes Mountains into Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil and Rio de Janerio.

 

Habitat: Dry grasslands, forested areas, the savanna and the underbrush of tropical rainforests.

Behavior: Red-footed tortoises will live in burrows dug by other animals. Groups of individuals will live together in the same burrow and exhibit semi-social behavior, meaning that they do not usually show territorial behavior.

 

The best protection that a tortoise has is its shell. While most tortoises cannot pull their entire bodies into the shell, they can pull their heads back and use their arms to block the opening.

 

Reproduction and rearing: Breeding occurs during the spring. Males approach other tortoises and exhibit a bobbing head movement. If the other tortoise is a male, he will respond with the same bobbing and the two will battle, seeking to overturn the other. If it is a female, she will not respond.

In order for mating to continue from there, the male and female must have "correct" coloration on the head; if they do, copulation occurs. During the whole process, the male makes clucking noises that sound a lot like a chicken.

 

The female will lay between 5 and 15 eggs in a nest that she's made. There is no parental care, so the eggs must be well hidden. After approximately 150 days, the eggs will hatch and the hatchlings are responsible for finding their own food. Sex is determined by the temperature at which the eggs are incubated. Temperatures above 88 degrees produce females. Incubation at below 82 degrees results in males. Anything in between those two markers results in mixed sexes.

 

Predators: Larger mammals such as foxes, dogs, jaguars and skunks. Rats prey on the eggs.

Lifespan: 50 to 60 years.

 

Conservation Status: The IUCN Redlist has not assessed the red-footed tortoise; however, populations may face issues due to habitat loss, as well as predation by humans. Red-footed tortoises are often eaten by people, particularly by Catholics in South American during Lent, as the tortoises are not considered to be meat by the Catholic Church.

 

Sources: www.zoo.org; beardsleyzoo.org; cinncinnatizoo.org; iucnredlist.org; Pueblo Zoo archives

-- Mo Walsh

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