Imagine you’re Charles Darwin, feeling you have a pretty good handle on the earth’s amazing biodiversity after exploring for four years and filling your ship, The Beagle, with  a multitude of live animal specimens for further study.  Then, off the coast of Ecuador, you and your crew come upon an archipelago called the Galapagos.   You realize then you most certainly haven’t seen it all!   And it’s no coincidence that Galapago is an archaic word in Spanish meaning tortoise.

Amazing Creatures

Greeting Darwin and his crew in 1835 were creatures such as the marine iguana, literally half of the Blue-Footed Boobies on earth engaging in mating rituals, the only flightless Cormorant species on earth, and a 3-inch painted locust that was capable of jumping ten feet in the air.   

But perhaps most famous and now beloved of his discoveries were the Galapagos Giant Tortoises. They were huge, they were docile, and they were everywhere.   It’s estimated that there were once 250,000 of them on the islands, and until humans discovered them, they really had no natural enemies. 

Perfectly adapted

The Galapagos Giant Tortoise subspecies vary slightly from island to island in the Archipelago, adapting perfectly to the different environments.   The major adaptation, though, has to do with shell shape – they sport either domed or “saddle-backed” shells (with an upward angle on the front of the carapace, which restricts how far UP they can extend their long necks).   It turns out that the tortoises living on more arid islands need the flexibility to reach higher up for their favorite food, the prickly pear cactus.   Those living on lush, humid islands only have to extend their necks forward to nab a delicious herbivorous dinner.

The Giant Tortoises lead a placid existence in the wild, and also in human care, sleeping up to 16 hours per day, basking in the sun, and occasionally wallowing in mud.   In the wild, Galapagos finches can often be found on their shells, symbiotically pecking pesky ticks from the folds of the tortoises’ skin.  

During mating season, things get interesting

Things perk up a bit during mating season, between January and August (depending on weather), when males may compete for females in a curious faceoff : it’s a neck-stretching and mouth opening contest, where the one with the longest neck gets the girl!  Mating can take hours, and is celebrated by the champion-necked males with an extremely loud roaring throughout.    

For visitors to the Reid Park Zoo, it’s often confusing when Ferdinand and Isabella, the two Galapagos tortoises, are enjoying this ritual.  Since the roaring is audible throughout the Zoo, guests flock to the lion habitat, but find them fast asleep – how can this be?

The females lay between 2 and 16 eggs about the size of tennis balls, burying them about 12 inches in the ground.   Then they walk away – so the hatchlings are on their own, right from the start.   The temperature in the nest will determine whether the babies will hatch as males or females. A few centuries ago, enough of these hatchlings survived to create a growing population of these long-lived giants.   Nobody can verify the life span of a Galapagos Tortoise, but it has been estimated to be up to 170 years.      

The Trouble Begins

 Spanish explorers first discovered the tortoises in the sixteenth century, and they quickly became an important shipboard food source for seafarers, including pirates, merchantmen, whalers, and yes, the crew of The Beagle.   

One of these giant tortoises’ amazing adaptations is the ability to go up to a year without food or water, making them the perfect, low-maintenance livestock onboard a ship.  They also have shells which look solid, but are very light due to a honeycomb structure.  And of course, they were very easy to capture, though maybe not to carry – some individuals can weigh more than 500 pounds. 

Also, settlers on the islands introduced invasive species, like pigs, goats, and rats, which began to consume the same plant life that had been central to the tortoises’ survival.   And of course, the tortoises were also used for food by the islands’ inhabitants.

Now they’re endangered

Originally, 14 different subspecies of the Galapagos Giant Tortoise were identified in the wild, but sadly, two of those subspecies are now believed to be extinct.   Best estimates are that only 10,000 – 15,000 altogether now survive in the wild.

But there is reason for hope

In 1959, the Ecuadorian government established Galapagos National Park in order to protect remaining habitat, and eggs began to be collected and incubated at the Charles Darwin Research Station on Santa Cruz Island.    Here at home, under the guidance of the Association of Zoos and Aquariums, Galapagos tortoise breeding programs began in accredited zoos .  The aim was to reintroduce members of the species to the wild once their habitats were deemed safe.  The San Diego Zoo alone has hatched more than 94 Galapagos tortoise babies through the years, enabling breeding programs to get started at other AZA zoos.  It takes patience though – breeding only begins when individuals reach the age of 20-25.

Way to go, Diego

There have also been some amazing in situ success stories.   A recent example is the tale of Diego, who had been living in the San Diego Zoo and  was returned to the Charles Darwin Research Station to help repopulate his kind on the island of Espanola.  In 1965, only 26 members of Diego’s species survived there.   Since his arrival back in The Galapagos in 1976, numbers have grown to nearly 2,000.   Diego gets credit for fathering roughly 40% of them, or around 800 new tortoises.   Diego will now live out his years – he’s over 100, but of course that’s probably just late middle age for a Galapagos tortoise!   He’ll enjoy many more serene years – back on his native island.   

Darwin would approve.

We’ve all heard about the importance of conserving energy – but there is one animal at the Reid Park Zoo that has been an expert in this field for about 200 million years. In fact, he’s so proficient at conserving his own energy that the two most common reactions from Zoo visitors are “Is that real?” and “Is it alive???” Yes and yes!

The American Alligator is one of the first creatures to greet guests when they enter the Reid Park Zoo (well, “greet” might be a little bit of an exaggeration), and that’s only fitting, since they’re one of the most ancient animals still living on earth. Often called a “living fossil,” the American Alligator is the largest reptile native to North America, and they really are a paragon of adaptation and survival. Amazingly, they have not changed much for the last 200 million years, though they’re a bit smaller than their mega-reptile ancestors. They have already overcome the “alligator shoes” craze of the 1960s, where they were hunted almost to extinction. Fortunately, the states where they lived got wise and began to protect them, and the species came roaring back. But now they’re in trouble again –  more about that later.

Bayou, the splendid American Alligator

Bayou came to the Reid Park Zoo in 2018 as a middle-aged gator – age 25. What is amazing is that he had lived with many other alligators prior to arriving here (where he enjoys the preferred solitary life of his kind in the wild) but he still has ALL of his toes! Since Alligators prefer living alone in the wild, when they’re placed in close quarters with others of their kind, they squabble, bicker, and nip at each other’s toes frequently .

Tucsonans are fascinated to see a real “swamp creature” in our midst, and it’s likely Reid Park Zoo guests will be able to get a good view of him sitting completely motionless underwater. You can clearly see his 9-feet of thick scales and his smiling upper teeth – so many of them! – which are visible even when his mouth is closed. Since alligators can continue growing all their lives, he might even be bigger the next time you see him. Anyway, it’s likely you’ll see him in the exact same position for quite a while, because Alligators can stay underwater for 30 minutes, easily. He will come up for a breath eventually, but likely just surfacing his raised nostrils, not his whole head. On warmer days, though, or when his keepers call him with the promise of treats, he’ll obligingly amble out of his pool (heated during the cooler months, of course!) and come onto the grass to bask in the sun.   

They’re really not that hungry 

American Alligators live naturally from Florida up to North Carolina, and also along the Gulf Coast into Texas. They thrive in swampy freshwater areas, streams, lakes and ponds. You’ve no doubt seen many news stories about them appearing on golf courses, wandering into people’s yards, or being washed into new territories by floods or other catastrophic weather events. Human development of their home territories has greatly increased the number of human-gator interactions, but it’s important to know that the American Alligator is way less aggressive than his cousin, the Crocodile. It’s true that Alligators  are able to run up to 30 miles per hour, but only for 11 seconds or so (remember – conserving energy is the name of the game). And they are not interested in eating you – you’re way too large and besides, they only need to eat once or twice a month in the wild. Studies have shown that a 100-pound dog will eat more in a year than an 800-pound alligator!

Still, as with all wildlife, it’s best to keep your distance. They may be fascinating and appear to be smiling at you, but you really don’t want to get anywhere near that mouth. The American Alligator spends all that time doing nothing to conserve his energy for lunging at prey such as fish, turtles, snakes, frogs, birds and small mammals. A gator has between 75-80 teeth in his mouth, and because of his hunting method – lunging, snapping the jaws down, and then thrashing his head to subdue the larger prey, he’s always breaking and losing teeth. But that’s no problem, because like sharks, the Alligator can constantly grow new teeth throughout his lifetime – up to 3,000. Then there’s the strength of those jaws clamping down – researchers have measured their bite force to exert somewhere between 2,000-2,900 pounds per square inch!

Alligators and the Environment

The American Alligator is a keystone species, which means that in the wild, they create changes to the landscape that benefit many smaller animals (elephants do this to their landscapes as well). In cooler weather, these giant reptiles dig “gator holes,” which fill up with shallow pools of water, and there they enter brumation, a sort of semi-hibernation. When warmer weather returns, the alligators abandon the holes, which then are used by snakes, turtles, fish, and other nearby creatures.

Maternal?

There is one thing, besides its size and amazing energy efficiency, which distinguishes the American Alligator from most other reptiles around the world. The truth is, most reptile females bury their eggs and walk away; what happens to their young after hatching is not their concern. But the female American Alligator is an unusually attentive mother. Females build huge nests of sticks, leaves, and other plant materials, and then lay 20-60 eggs in them. They then create a mounded cover for the nest out of grasses and mud. This will enhance the temperature inside the nest, which can end up about 10 feet in diameter and 3 feet high. As if that’s not enough, female gators guard these nests from predators, including other alligators. After about 65 days, the occupants of these eggs begin to loudly peep, signaling that hatching is beginning. Amazingly, the mothers can gently carry up to ten of the young in their mouths, so she immediately takes them to safer ground, where she will do her best to protect them for up to a year.

Trouble is brewing

But what’s happening inside these 3-inch long alligator eggs during incubation? It’s the reason this incredible species may now be facing a threat greater than the craze for purses, briefcases, and shoes made from their hides. The gender of American Alligator hatchlings isn’t determined until about 30 days into the incubation period, and gender depends on the temperature inside the nest. The nests are so large they naturally have some variation in temperature inside them, so some eggs should produce females and others males.  

But the trick is this – if it’s too cold (below 88 degrees) during incubation, the hatchlings will all be female, and they’ll have high mortality rates. If it’s too hot in the nest (above 96 degrees or so), the eggs will also produce all females, and they too will have high mortality rates. There is a sweet spot, between about 90-92 degrees, where the eggs are likely to produce males. Climate change, particularly the warming of the alligators’ natural habitats, is already greatly affecting the proportion of male alligator hatchlings, because it’s just getting too hot inside the nests now.   

There’s hope

But by learning ways to live more sustainably (for example, simple things like limiting single-use plastics), even individuals can begin positively affecting the prospects for the American Alligator and all the other amazing animals on earth – oh, and for humans, too. So come to the Reid Park Zoo, learn how you can fight climate change, and get to know and appreciate the amazing American Alligator. That will make it even more fun to anticipate meeting his Indonesian cousin, the Komodo Dragon, in the Reid Park Zoo expansion!

From that tiny common side-blotched lizard scurrying under your garage door to the bold Eastern Collared Lizard calmly basking right in front of you, our desert lizards have amazing ways to survive and thrive. If you’ve lived here a while, you’ve probably encountered hundreds of them. But now, Tucson, it’s time to meet The King of the Lizards.

The Reid Park Zoo’s expansion will be bringing us the biggest lizard on earth – the Komodo Dragon. These real-life fairytale creatures are huge, they’re fascinating, they’re apex predators, and they’ve been around for 100 million years or so. And though they have no natural enemies, they’re now vulnerable in the wild.  

They’re Huge.  And Hungry.

These giants average about 10 feet long and 154 pounds for males, and the largest Komodo Dragon on record was 10.3 feet long and weighed 366 pounds. And they’re incredibly strong, especially in the muscular jaw and neck area. They are such efficient eaters that they can eat up 80% of their own body weight in just one day. Luckily, their stomachs can expand. And they have another useful trick for that sluggish feeling you get after overeating. If they sense a threat and need to flee quickly, they simply throw up their stomach contents and lose the extra weight.

What about that fearsome bite?

The Komodo Dragon is an ambush predator, lurking patiently by the side of known wildlife paths to conserve energy, then leaping and striking when a tantalizing animal passes by. Its favorite meal in the wild is the Timor Deer, but it will eat anything from large water buffalo to its own newly-hatched offspring.

The Dragons’ teeth are large, they’re sharp, and they’re serrated. They’re also breeding grounds for bacteria, since their particular brand of oral hygiene, leaving scraps of their previous meals on and between their choppers, encourages the development of around 50 different bacterial strains. Seven of these are highly septic and thrive in the dragons’ saliva. As if that weren’t enough, researchers have also located a venom gland in the lower jaw, and that venom happens to be an anticoagulant. The effects of a dragon bite are generally profuse bleeding and the onset of sepsis. The victim will often flee, but after a few days, will surely succumb to the attack. And the Komodo Dragon has an acute sense of smell (via its flickering tongue) which can locate its injured prey even when it’s miles away.

Luckily, because the Dragons tend to scuffle with each other when they’re feeling peckish, this lethal bite has no effect – except perhaps for some disfiguration – on their fellow lizard kings.

Those poor little things.

Let’s begin with the hatchlings, whose sometimes unfortunate fate was alluded to above. Komodo dragons are generally solitary, but breed annually, though the female individuals lay eggs only every two years. Clutches are between 15-30 eggs.  But as the females are naturally solitary creatures, if it’s their year to lay eggs, they can always skip the actual breeding and through parthenogenesis, lay perfectly fertile eggs without the assistance of a male. Well, not perfectly fertile – all the “fatherless” hatchlings will be male.

The eggs are roughly the size of grapefruit, and are laid in nests on hillsides, on the ground, or in  mounds which have been vacated by another indigenous species, the orange-footed scrub fowl. Female  Komodo Dragons have also been known to dig decoy nests to protect the eggs from predators, including fellow Dragons. Some females behave in a maternal fashion for the three months of incubation, guarding the eggs, but others, like so many reptiles, simply lay the eggs and abandon them. Hatchlings lucky enough to make it to hatching immediately scramble up the nearest tree, where the heavy, hungry adults of their kind can’t reach them. They’re  about 16 inches long and are precocial – ready to find their own food right away. There’s plenty of food available up in the trees, and the young Dragons will enjoy this arboreal period of their lives for about 4 years, finally coming down when they’re around four feet in length.

The Daily life of an adult Komodo Dragon

The Dragons are indigenous to five islands in Indonesia, four in Komodo National Park (Komodo, Rinca, Gili Montang, and Gili Dasami) and another island outside the park, called Flores.

The mostly solitary life of adult Komodo Dragons consists of four things: hunting, eating, basking in the sun (they’re ectothermic), and lots and lots of sleeping. Most of these require very little energy, and researchers have discovered that even though these reptiles are capable of travelling long distances, they almost never stray from the areas where they and their progenitors have always lived.   

They do have great homing abilities, though, as demonstrated by an experiment in which adults were relocated on their native island, as far as 13.7 miles away from their home. Within four months, all of the dragons relocated on land had returned to their home territories. However, those relocated across a waterway, though they are perfectly capable of swimming, seemed to decide it was too much trouble – or perhaps too great an expenditure of energy, to return to their ancestral homes and adapted to the new locations without much fuss.

Why is this species now considered vulnerable?

Their numbers in the wild are decreasing, largely through human encroachment, habitat fragmentation, the illegal wildlife trade, and the burning of grasslands in order for humans to hunt the Dragons’ favorite prey, the Timor Deer. Also, as evolutionary stars, they generate a substantial amount of income for Indonesia through tourism – where guides feed them unnatural foods to make them drowsy and suitable for photographs with tourists, while those tourists, even if they don’t mean to, are altering the Dragons’ natural environments just by being there.   

The research and breeding of Komodo Dragons that can be safely done in human care is now more important than ever. The Reid Park Zoo hopes you’ll come see this most amazing lizard once the Pathway to Asia expansion is complete! Just by visiting, you’ll be helping the Zoo in their efforts to conserve these ancient and fascinating creatures.