Gopher Tortoise: Ecosystem Engineer

The gopher tortoise is the only American tortoise found east of the Mississippi and is an engineering prodigy. As many as 350 other species of animals rely on the complex, sprawling burrows these tortoises create. This means they are a true keystone species.

Find out more amazing facts about this lovable builder, its behaviors, and the many other animals that rely on the gopher tortoises engineering prowess to survive!

Gopher tortoise burrow commensals include

The gopher tortoise is protected because it is

The gopher tortoise is considered to be

The gopher tortoise relies on armadillos to excavate the burrows they live in.

Gopher Tortoise: Keystone Species

The gopher tortoise is protected throughout its range, but not because it’s endangered. It’s protected because as many as 350 other species of animals use the sprawling networks of burrows they create for their own shelter. We refer to these animals as burrow “commensals.”

Because the gopher tortoise is so pivotal to the life-cycles and well-being of so many other animals, it’s a great example of a keystone species. A keystone species is a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically.

Can you think of an animal or plant in a nearby ecosystem that would also be considered a keystone species? What do you think would happen if that species suddenly disappeared?

The Gopher Tortoise: Ecosystem Engineer

Habitats are shaped by and adapt to lots of different biotic and abiotic factors. In the case of Florida’s pine flatwoods, wildfires are not just a frequent fact of life, but they help to keep these habitats healthy. I know that might not seem logical, but it’s true. Plants that make up this habitat have adapted to survive frequent burns. If fire doesn’t sweep through every 3-7 years, other invasive plants can take over. Today, ecologists actually perform what are called “prescribed burns” to fire-adapted habitats like the pine flatwoods to keep them vibrant.

I know what you’re thinking: how do animals survive a wildfire? Well, most can simply outrun the blaze. But what about those that are a little more… speed-challenged, like the gopher tortoise? Worry not, thanks to the gopher tortoise.

These reptiles won’t win the 100 yard dash, even in turbo mode. They’re shy and can sense vibrations from far away, giving them time to hide. At my property near the Fisheating Creek River, I rarely see them, but I find their signs all over the place.

“Here’s some gopher tortoise poop: scat, if you want to be technical about it. It’s really not that offensive because these animals are herbivores so it’s pretty much all grass and organic matter.”

A year ago, a prescribed burn was performed on this section of pine forest.  Days after the burn, we discovered a dozen burrows which had been hidden by the dense palmettos. These holes were made by gopher tortoises. By the way, this is what the forest looked like just after the burn and this is what it looked like less than a year later.

Out of curiosity, I set up trail cameras on a few burrows. Gopher tortoises are important ecosystem engineers. An ecosystem engineer is a species that creates, significantly modifies, maintains, or destroys a habitat. Woodpeckers and beavers are other great examples of ecosystem engineers.

Gopher tortoises excavate massive underground lairs as long as 40 feet and the burrows are deep enough for them, and other critters, to survive a wildfire. In addition to the tortoises, the burrows shelter as many as 350 other species of animals, like armadillos and the endemic Florida mouse. This makes the gopher tortoise an important keystone species (show definition). The burrows and the habitat the tortoises create are so important to the survival of so many other critters and I want to know more…if only I could get a glimpse into their subterranean world.

“So what I have here is basically a $300 inspection camera, and it has a 10 foot fiber-optic cable, a tiny little camera… it’s the perfect tool for getting a glimpse into a tight spot like a gopher tortoise burrow.”

The burrows attract a lot of insects. Also, amphibians like gopher frogs, which eat a lot of those insects.

A few species of snakes are also gopher tortoise commensals. They’re decent roommates even though they don’t pay rent. Commensalism, by the way, is a symbiotic relationship in which one organism benefits, and the other neither benefits nor is harmed. The eastern coachwhip, one of the fastest snakes in North America, is a common tenant and the burrow is a great place to find a date.

Some animals seem to visit out of curiosity (shot of deer faun), others come for the food. Bobcats have gotten the memo. Maybe there’s a Florida mouse down there somewhere.  This one managed to nab a rabbit at the entrance of a flooded burrow. Looks like it’s take your kitten to work day. That stump must smell and feel amazing.

The sandy apron of the burrow entrance is where the tortoises lay their eggs.  Armadillos and raccoons are notorious nest-raiders and love eggs of all kinds (include causeway egg thief footage). The grim truth is that hatching success rates are super low for these reptiles, but hey, they’ve got to keep trying.

Head bobbing is used to entice a female, or, to pick a fight. When they’re not trying to procreate, males often engage in ultraviolent jousting matches. It’s like watching a cage match. At half speed. Stronger males will have greater reproductive success.

In 2017, Hurricane Irma brought torrential rains to our gopher tortoise colony. So, what did these terrestrial tortoises do when they found their homes underwater? We were surprised to see them dunk right in, probably to cool down from the Florida heat. How long can the tortoise hold its breath? We don’t know exactly…but apparently a long time. Though more comfortable on dry land, it turns out the gopher tortoise doesn’t mind taking a dip and is a halfway decent swimmer.

Reptiles can’t maintain body temperature through metabolic processes, so they have to use the environment to thermoregulate, to cool down, or warm up. After a big meal of veggies, gopher tortoises spend a lot of time basking in the sun. It’s a rough life.

“Oh no, oh shoot, can you see right here? I think we’ve got some predation. See if you can bring that camera in close. Oh that is too bad. Um, those are gopher tortoise eggs. Their hatching success rate is so low and that’s because of predators like raccoons and armadillos. But, we’ll have to see what’s on our camera traps. We’ll probably find the culprit there.”

What we discover is completely unexpected. A large aquatic Florida softshell turtle has decided to lay its eggs in the sand at the entrance to the burrow. It turns out that sandy apron created by the gopher tortoise’s excavation is a great place for other turtles to lay their eggs too. Three hours later, a raccoon has found the egg chamber. It’s a massacre for the softshell. But this turtle is much more common than the gopher tortoise and will lay many more eggs during its lifespan. Nature can be harsh, but left alone, it does find balance.

The gopher tortoise is the only American tortoise species east of the Mississippi. It can grow to about a foot long and can reach a ripe old age of 90. This species prefers sandy, upland habitats in the southeastern United States (range map), and is protected throughout its range. Habitat loss, however, is an ongoing threat for this keystone species. Protecting this reptile, means protecting its habitat along with 350 other animals that rely on the tortoises’ important networks of burrows. Just one more reason to keep our wilderness areas wild.

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