American Herping: A Guide to Reptiles and Amphibians in US Zoos

While I know this is an old post, I have unfortunate news about one of the rarities in this thread. As of my visit today, Buffalo Zoo no longer displays Dumeril's monitor. I have no idea what happened to this individual, whether it passed, was moved off-display, or was transferred elsewhere, however what I do know is it isn't on display, making this one of (if not the) first species on this thread to no longer be exhibited in a US zoo. To add insult to injury, their replacement is a very common species that I personally find to make rather poor exhibit animals: the Brazilian rainbow boa.

 

Zoo Atlanta also holds them but based on Zoo Knoxville’s statement they are probably BTS.

Edit: Honolulu also has them on display as well.

 

Apologies for the delayed response. Re: Angonoka Tortoises... Knoxville and Honolulu were the two holders in my survey, and are the only two places I know that display them.

Asian Tortoises

Asian Forest Tortoise (Manouria emys) – Common

Known by a variety of interchangeable names – Asian Brown Tortoise, Mountain Tortoise, etc – this critically endangered tortoise is the largest of its kind in Asia, and can be identified by its size and dark brown or black shell. It is considered to be the most basal tortoise species (“primitive” though I’m not a fan of that phrasing – essentially, it is the most similar to early tortoise ancestors). There are two subspecies: the nominate southern type from the Malay Peninsula and Indonesia, and the northern phayrei type from India, Burma and northern Thailand. The phayrei subspecies is also called (though not consistently) Burmese Black/Brown/Mountain Tortoise, and is the primary subspecies found and bred in US zoos – although there are a few M. e. emys present as well.


Taken at Zoo Knoxville by @Coelacanth18

Star Tortoises (Geochelone) – Common

Named for the intricate lined patterns on their shells, fairly similar to the Radiated and Spider tortoises of Madagascar. There are two species; the more common (over 70% of holdings) is the Indian Star Tortoise (G. elongata), but the related and more endangered Burmese Star Tortoise (G. platynota) is also found in a handful of zoos and are being actively bred.


Indian Star Tortoise; taken at Chattanooga Zoo by @ThylacineAlive

Indotestudo – Prevalent

A genus of three small forest tortoises, often with black-blotched scutes. Two species – the Elongated Tortoise (I. elongata) of mainland tropical Asia and the Forsten’s Tortoise (I. forsteni) of Sulawesi and nearby islands – are uncommon but found in a handful of US zoos each, while the Travancore Tortoise (I. travancoria) of southern India is famously only known from the Philadelphia Zoo.


Elongated Tortoise; taken at the Chattanooga Zoo by @ThylacineAlive


Forsten's Tortoise; taken at Zoo Knoxville by @Andrew_NZP

 

Good Ol’ American Tortoises (genus Gopherus)

It's hard not to get excited about the colorful tortoises of Madagascar, India, and other far-flung abodes... but to paraphrase a once-popular meme, "We have tortoises at home."

The Gopherus tortoises of North America are not the largest or most colorful species, but they are nonetheless present in many zoos here and this is (unsurprisingly) the best place in the world to see this genus with 5 of the 6 species found in the survey - and in considerable numbers for two of them.

Gopher Tortoise (G. polyphemus) – Prevalent to Common

The one that started it all! Native to the southeastern US, the species name polyphemus means “cave-dwelling” and came from their ability to dig huge cavernous burrows. These dens provide habitat for hundreds of other species, making the tortoise an important player in the local ecosystem – though unfortunately they are Vulnerable due to various issues like habitat conversion, climate change, poaching and disease.

The captive hotspot for this species is Florida (where most wild individuals live); most major zoos and several smaller facilities and nature centers in that state display them. That being said, several other holders are found scattered throughout the eastern half of the country.


Taken at the Naples Zoo (Florida, not Italy) by @red river hog

Desert Tortoises – Prevalent to Common

Mojave Desert Tortoise (G. agassizii)
Sonoran Desert Tortoise (G. morafkai)

Found in the deserts of the Southwest, desert tortoises serve a similar niche of burrow diggers for desert denizens like burrowing owls, antelope squirrels, rattlesnakes and Gila monsters – all of whom will move in with the tortoises, and increasingly so as rent in California has become too unaffordable without roommates. Critically endangered, young tortoises are frequent food targets for a ballooning raven population in the Southwest while adults are impacted by speeding cars and habitat conversion; the brutal heat waves of late have also not helped. Fortunately, this species has become a high-profile conservation focus in the region and multiple zoos are involved in “head-starting” baby tortoises (raising them safely to a respectable size with ample food) for eventual release.

The Mojave and Sonoran populations were split in 2011 based on several differences between the two. Most in zoos are signed as the original G. agassizii, now representing just the Mojave tortoises; whether this is because of slow uptake to new taxonomy or because the vast majority of captive tortoises are actually of Mojave origin is unclear to me, but at least a couple of places specify their tortoises as the new morafkai.


Adult; taken at the Los Angeles Zoo by @Coelacanth18


Juvenile; taken at Living Desert (California) by @Coelacanth18

Texas Tortoise (G. berlandieri) – Rare to Uncommon
Bolson Tortoise (G. flavomarginatus) – Rare

Two more Gopherus tortoises that look similar to the aforementioned species; the Texas Tortoise is found in southern Texas and Mexico and captively in a small handful of zoos. The Bolson Tortoise – the largest species of the genus, with a domed carapace – is endemic to Mexico in a small area of the Chihuahuan desert, and I only found it in a couple of captive facilities close to that area near the US-Mexico border.

 

Bolson Tortoise also has an introduced population in New Mexico.

 

I wonder if any rescue or zoo has mislabeled Goode's Thornscrub Tortoise(Gopherus evgoodei) as Mojave Desert Tortoises. the split into a new species very recent, might be a candidate for future in-situ programs.

 

Possible, but not that likely if I had to guess. More likely the desert tortoises in US zoos are derived from local animals, which would be either agassizii or morafkai.

South American and Giant Tortoises

We’ll be finishing up the tortoises – and thus all the chelonians – today with a banger: two of the largest reptiles on the planet. But before that – two smaller ones.

Red-footed Tortoise (Chelonoidis carbonarius) – Abundant
Yellow-footed Tortoise (Chelonoidis denticulata) – Prevalent to Common

It may come as a surprise that the Galapagos Tortoise has two smaller cousins on the mainland – until you remember that those island tortoises had to come from somewhere found in the northern tropical zones of South America, these tortoises can still grow to a respectable 1 to 1.5 ft long on average. Despite having names that seem pretty straightforward, the colors on these two tortoises are actually variable and in practice they are difficult to tell apart, especially for casual observers (as most of us are). Very common species in the private trade, they are also common sights in zoos of all types. They are both vulnerable in the wild, due to habitat loss and overharvesting for food and the pet trade.


Taken at the Naples Zoo by @red river hog

Galapagos Tortoise (Chelonoidis niger) – Abundant (mostly in AZA)

These famously large tortoises are the largest tortoises and one of the largest reptiles on Earth, with some individuals getting well over 800 lbs with carapaces 6 ft long. They are also one of the longest-lived vertebrates, with individuals known to have reached 175 years of age; incredibly, some of the Galapagos tortoises in American zoos are older than the zoos themselves!

Several islands in the archipelago are inhabited by different races of tortoise; there has been back-and-forth on whether to categorize these as subspecies, separate species, etc. Multiple types are present in the ~50 US zoos that hold them – microphyes, vicina, porteri, vandenburghi, etc – and there are some physical differences between the types. Most zoos simply sign them with the all-encompassing Chelonoidis niger, but significant efforts have been made in US zoos to have type-specific breeding herds. Some zoos with successful breeding results have been the San Diego Zoo, Riverbanks Zoo (of leaf-tailed gecko fame), and the Gladys Porter Zoo in Texas. Captive-bred tortoises from the States have been sent to the Galapagos for repopulation efforts, as these tortoises declined a lot in the past few centuries due to human activity.

A short explanation of some of the genetic work and collaborative breeding strategies of recent years: Galapagos Tortoise Research



Both Galapagos Tortoises, but with differing shells
Taken at the San Diego Zoo by @Coelacanth18 and @red river hog

Aldabra Giant Tortoise (Aldabrachelys gigantea) – Abundant

Across the world on another set of islands, Nature produced another group of huge tortoises that have survived human contact. Native to the Seychelles off the coast of East Africa (mostly on the atoll of Aldabra), the Aldabra tortoise averages smaller than a Galapagos but is still easily the second largest tortoise. This species is somewhat more likely to be found outside of AZA zoos than Galapagos, although the large majority of holders are accredited. Despite being one of the most common reptiles in US zoos with ~85 holders, breeding this species has proven incredibly difficult; only a small handful of zoos have ever accomplished it, and the only zoo with a successful active breeding herd is the Tulsa Zoo with over 100 hatchlings since 2000.


Taken at the Pittsburgh Zoo by @Andrew_NZP

------------------------------------------

As with each group so far, there will be a summary post for chelonians; it will go up early next week and be followed by an introduction to our last major herp group. We're almost to the end, folks!

 

The birds section is going to take a while.

Incidentally--at my last visit to the Philadelphia Zoo a couple months ago, I saw what I think was their male Galapagos tortoise trying to mate with one of the female Aldabras (they share a yard).

 

I think it will somehow be even longer than the mammal section!
(Amphibians are already included in this thread, so if being truly monophyletic... )

 

TURTLE RECAP

The Topline Numbers
176 species from 13 families
2 species were added from contributions to this thread

Families with the most species:
Emydidae (American pond turtles) and Geoemydidae (Asian pond turtles) – 36 species each

Family with most survey holdings:
Testudinidae (tortoises) – 471 holdings for 34 species

Species abundance breakdown (with borderline cases sorted into higher of two bins):

- 11 Abundant (40+ holders)
- 7 Very Common (30-39 holders)
- 5 Common (20-29 holders)
- 27 Prevalent (10-19 holders)
- 31 Uncommon (5-9 holders)
- 95 Rare (1-4 holders) (54% of total)

Turtle holdings are slightly less scattered than other herp groups so far, although not by a whole lot. Roughly ~25 species are common to abundant; ~60 species are less common but still held in several or more places; and a block of fairly rare or unique species make up slightly over half the group’s total diversity. Native turtles made up ~30% of species held, a proportion similar to snakes and higher than lizards and amphibians.

Top Performers
The most common turtles in the survey were the Alligator Snapping Turtle and Common Box Turtle, which were within the margin of error for top spot. That being said, the survey results definitely undercounted some species such as tortoises, with the total number of Aldabra holders easily eclipsing the survey results of those top species. The most common species in the survey are listed in the spoiler below, in order of when they were covered:

Spoiler: Most Common Species

Matamata Turtle (Chelus fimbriata)
Yellow-spotted Amazon River Turtle (Podocnemis unifilis)
Fly River Turtle (Carettochelys insculpta)
Green Sea Turtle (Chelonia mydas)
Alligator Snapping Turtle (Macrochelys temminckii)
Common Snapping Turtle (Chelydra serpentina)
Common Box Turtle (Terrapene carolina)
Ornate Box Turtle (Terrapene ornata)
Painted Turtle (Chrysemys picta)
Pond Slider (Trachemys scripta)
Diamondback Terrapin (Malaclemys terrapin)
Spotted Turtle (Clemmys guttata)
Black-breasted Leaf Turtle (Geoemyda spengleri)
Pancake Tortoise (Malacochersus tornieri)
African Spurred Tortoise (Centrochelys sulcata)
Leopard Tortoise (Stigmochelys pardalis)
Radiated Tortoise (Astrochelys radiata)
Spider Tortoise (Pyxis arachnoides)
Asian Forest Tortoise (Manouria emys)
Red-footed Tortoise (Chelonoidis carbonarius)
Galapagos Giant Tortoise (Chelonoidis niger)
Aldabra Giant Tortoise (Aldabrachelys gigantea)

Unsurprising that one of our most iconic reptiles - the Alligator Snapper - also breaks into the top 10 list for survey holdings of all reptile/amphibian species
Taken at the Belle Isle Aquarium (Detroit) by @Lucas Lang

Notable Facilities

Turtles and tortoises are popular zoo animals, even for smaller zoos that don’t have a dedicated reptile house. Plenty of larger zoos have a decent collection, but a few stand out from the rest. The largest on-display collection for a traditional zoo is the Bronx Zoo with ~45 species of chelonian. Three other zoos sit in a lower tier than Bronx, but higher than everyone else: the San Diego Zoo and Zoo Knoxville with ~35 species and the Columbus Zoo with ~30 species. As mentioned earlier Asian chelonians are a primary conservation focus for US zoos, and a large proportion of the chelonians at all four of these zoos are of Asian origin. All of them are established turtle breeders, with Knoxville in particular having a specialty in breeding and championing endangered turtles and tortoises – highlighted by their new ARC complex.


Greenhouse with pens for Asian turtles and tortoises, new as of 2021
Taken at Zoo Knoxville by @Coelacanth18

Even Bronx, however, can be outclassed. Head and shoulders above any other US aquarium, the Tennessee Aquarium in Chattanooga displays a whopping ~55 species, including several that rotate in an on-view nursery. The aquarium is not only an important breeding hotspot for many an endangered turtle, but compared to the aforementioned zoos it is very well-balanced geographically – with species from every continent and a focus on both Asian and North American turtles, with probably the largest collection of native turtles on the continent. With Knoxville being a mere 2 hours away, West Tennessee has emerged as a major hotspot for captive chelonians.


The River Journey building might have more turtles inside than any other building in North America
Taken at the Tennessee Aquarium by @geomorph

As far as reptile specialist zoos go, most are indoor facilities that are slim on chelonians. A glaring exception to this is Iguanaland, which you might remember from the lizard summary. Despite its name, this 2 year old reptile zoo in southwest Florida has almost as many turtles as it does lizards; despite being open for less time than I’ve been working on this project (!!) they already exhibit ~80 species of chelonian, making them the largest on-display collection in North America that I'm aware of.

Rising Stars
Normally this section highlights species that are rapidly becoming more common on the scene. Truth be told, it’s always been the hardest one to write – due to the fact that we don’t have an American version of Zootierliste, and the fact that older and newer references on the forum are hard to compare because nearly all herps get mentioned on the forum more now than 10 or 15 years ago. There was no one species that clearly stood out this time, but if any older members have input about what turtles they see a lot more now than in the past it would be very welcome!

Coely’s Highlight Species
With every major group I will highlight at least one personal favorite of mine.

Narrow-headed Softshell Turles (Chitra)

The first time I saw one of these giant turtles was many years at the Saint Louis Zoo, which has a C. chitra in one of the atrium turtle pools of their historic reptile house. I don’t exactly know what captivated me about a giant flat turtle half-buried in the sand, yet to this day it remains a favorite turtle of mine. Some of the best news I’ve ever heard on the forum was roughly one year ago, when the San Diego Zoo hatched dozens of C. indica after 20 years of monitoring their three adult turtles. This remains one of my favorite things to see at San Diego, and my heart is warmed at the thought that one day these turtles could spread out to other zoos and give many more people the chance to see one… if they deign to poke out from the sand, that is


Not one for action or stress, this C. indica has chosen to hunker down in its little sand pool... I suspect most of us can identify with this on an emotional level
Taken at the San Diego Zoo by @Coelacanth18

And with that, Chelonia is now complete. Tomorrow I’ll jump right in to the final group… the birds!

Just kidding you all know what’s next.


Lurking under the surface, patiently biding their time to strike into this guide...
Taken at the Jacksonville Zoo by @Pleistohorse

 

I'm surprised they are one of the most common turtles in the survey. I've recently seen my first one ever at Toledo Zoo, compared to that there are at least seven species that I've seen in 6-8 different facilities (spurred tortoise, red-footed tortoise, aldabra tortoise, spotted turtle, fly river turtle, yellow-spotted amazon river turtle). I probably wouldn't have guessed alligator snapping as being in the ten most common turtles, let alone ten most common herps.

 

Tuatara next?

 

I'm not too surprised, as mentioned before, they are common in facilities of all sizes across the Midwest and South, from nature centers to major zoos. I've even seen them at CAS out west.

I think a majority of zoos in the US are in the Midwest and South, so any species popular in those regions will stand to have more weight in rankings.

 

Slight regional differences and anecdotal experience will explain this. ~70% of the Alligator Snapping Turtle holders I found are from the South and Midwest, compared to 60% of total places surveyed - so a bit more common in those regions, but not significantly unequal.

The regional spread of the 138 facilities I surveyed tracks almost exactly with each region's census population: ~35% from the South and 20-25% each from the Midwest, West and Northeast.

Check page 8

 

Very much looking forward to the upcoming posts. Curious to know what you found location wise for a particular species

 

Order Crocodilia

We’re almost at the end of the guide! The crocodilians are the last herp group to be covered, and as the order contains fewer than 30 species it won't take as long to cover them as previous groups. Found primarily in the tropics, they are carnivorous and some species are the apex predators of their habitats. Although mostly solitary and territorial, they can be found congregating in one area for food or mating opportunities – and unlike most other reptiles, crocodilian mothers continue to care for their young after hatching.

There are 28 or so species of crocodilian, including some recent splits. Due to those splits it's no longer clear if every species is present in the US, but every genus and visually distinguishable "type" is represented in captive collections. I will cover it a bit more in the summary post, but it’s already well-established that the King K. Rool of American zoos is the St. Augustine Alligator Farm in Florida, which at one point was considered to have every species of crocodilian in the world.

A few notes before I start covering species:

• Crocodilians are the only herp group for which we *do* have a fairly comprehensive holding list – compiled originally by @Hipporex and found here: https://www.zoochat.com/community/threads/crocodilians-in-american-zoos.477506/ With this great resource at our disposal, I will often use the numbers from this thread to calculate abundance rather than my survey results (except in a couple of cases where I know that list is outdated/incomplete) and will include an estimate for what number of places hold them.
• Many crocodilian holdings are concentrated in Florida (and more generally the coastal Southeast), where there is an abundance of parks dedicated specifically to them. As such, I will note when there is an uneven distribution of holdings.
• Since this is a much smaller group than all the previous ones, I will have the luxury of covering every species individually to some extent; even doing this it will only take me a couple of weeks to cover the whole order. So for all of you that pouted about the lists of names tacked to the end of posts… those days are officially behind us!

Family Alligatoridae

American Alligator (Alligator mississipiensis) – Abundant

The most common species in the entire herp survey, the alligator is arguably the most iconic American reptile - only possibly rivaled by the rattlesnake. Native to the rivers and swamps of the southeastern United States – particularly in Louisiana and Florida – this reptile was once an endangered species due to hunting, and its rebound in the late 20th century is a notable conservation success story for the US and for the Endangered Species Act passed in the 1970s. Broad-snouted and dark in coloration, these giant reptiles will bellow at each other to establish territory while the young make a variety of very cute chirping and squeaking noises.

Given its fame, it is probably unsurprising that they are the most ubiquitous reptile in captive facilities here. At least 145 zoos and aquariums in the US hold American Alligator, and even that number is likely an undercount. While many (possibly a majority) of holders are in the South, plenty of northern zoos have them as well - frequently in outdoor enclosures, which they can inhabit for much of the year thanks to having a higher cold tolerance than tropical crocodilians.


Large adult gator; taken at Busch Gardens Tampa by @Pleistohorse


Smaller gator; taken at the Virginia Living Museum by @Astrotom3000


Young gator; taken at the Conservancy of Southwest Florida by @red river hog

Chinese Alligator (Alligator sinensis) – Common

Visually similar to its American cousin except they are half the size. Native to eastern China, they live in a climate roughly similar to the American Southeast and have a similar cold tolerance. After declining for a long time due to its wetland habitat being converted to rice paddies, a confluence of that and other factors led it to the brink of extinction in the late 1990’s. Since then the population has stabilized, but the species is still Critically Endangered. A breeding program exists for this species here in North America; ~25 zoos hold Chinese Alligators, the vast majority of which are AZA accredited.


Adult; taken at the Shanghai Wild Animal Park (China) by @Ding Lingwei

 

very much looking forward to seeing how many true New Guinea vs Hall's New Guinea Crocs there are (as well as for Nile Crocs vs Desert Crocs!). asfaik the US doesn't have any Central African Slender-Snouted Crocodiles or Congo Dwarf Crocodiles so I'm excited to see if that has changed

 

Family Alligatoridae
Subfamily Caimaninae (Caimans)

Neotropical relatives of the alligators. Found from Mexico to Argentina, this family contains six species of generally smaller crocodilians. Unlike the Chinese Alligator and many crocodiles, all of the caimans are considered numerous and fairly secure in the wild. All six species are present in US captive collections, though one species is notably more common than all the others.

All of our photos today come courtesy of our northern neighbor, Canada.

Paleosuchus – Dwarf Caimans

Cuvier’s Dwarf Caiman (P. palpebrosus) – Common
Smooth-fronted Caiman (P. trigonatus) – Uncommon to Prevalent

These two dwarf caimans are among the smallest crocodilians (alongside the dwarf crocs of Africa) at 4 to 5 ft long as adults. Both found in tropical South America, they somewhat resemble juvenile alligators that never grew up. Fish and amphibians make up a large portion of the Cuvier’s diet, while adult Smooth-fronted (which are a bit larger) have a taste for small mammals, birds and lizards. Their small size makes them popular for indoor exhibits throughout the country, especially the Cuvier's; there are ~25-30 holders of Cuvier’s and ~10 holders of Smooth-fronted.


Cuvier's Dwarf Caiman; taken at Reptilia (Ontario) by @StellarChaser

Spectacled Caiman (Caiman crocodilus) – Uncommon to Prevalent
Yacare Caiman (Caiman yacare) – Rare to Uncommon, Regional

A medium-sized caiman, the Spectacled Caiman is the most widespread caiman in the world - found from Mexico down to Argentina. It is named for the bony ridges above its eyes – perhaps harkening back to a time when anyone’s spectacles looked like that. While all caimans are more numerous in European zoos than in North America, the Spectacled Caiman is particularly abundant across the pond with well over 100 holders; they are decently common in Japanese zoos as well. This makes the lack of them here (~10 holders, scattered throughout) a bit perplexing… perhaps many zoos have chosen to stick with the easy option of native alligator instead?

The Yacare Caiman of southern South America is visually almost the same as Spectacled, and while traditionally it is recognized as a distinct species the actual truth is murky. Only a small handful of zoos in the US display Yacare, of which I only know of one - Connecticut's Beardsley Zoo - outside of the Southeast.


Spectacled Caimans; taken at the Granby Zoo (Quebec) by @Pier-Luc Chouinard

Broad-snouted Caiman (Caiman latirostris) – Uncommon, Regional

The third member of the OG Caiman genus, the stubby snout of this crocodilian makes it look similar to some alligators. Only a handful of places in North America display this species, most of which are in Florida; the only northern holder I could find is the Montreal Biodome.


Taken at the Montreal Biodome (Quebec) by @Andrew_NZP

Black Caiman (Melanosuchus niger) – Rare

The largest species of caiman, rivaling real crocodiles with a max length of 20 ft. Found mainly in the Amazon, this seems to be the rarest caiman in US captivity; the only place I’m sure that displays them to the general public is the St. Augustine Alligator Farm in Florida.

 

Phoenix Herp Sanctuary has 8 black caiman total between two enclosures all on public display. They have Yacare and Broad Snout
as well and breed them regularly

 

Thanks for the additions. Phoenix Herp Sanctuary is a place that I knew had quite a few crocodilians, including rarer species. I excluded it from the survey and left it out of my write-ups because their collection was sort of a black box to me, and while I knew they did public guided tours I wasn't sure what animals could be seen during those tours.