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

Family Ranidae – “True Frogs”

The most stereotypical frogs: smooth skin, webbed feet, large and powerful legs, mostly aquatic. The family is found throughout the world, but all 10 species in the survey were native to the US; this is similar to Europe and Japan, which also hold primarily their own Ranidae. They are from either the genus Rana or Lithobates, depending on your taxonomy; zoos may sign them as either.

Note on the asterisks: I adjusted the abundance up from the actual survey numbers, based on their prevalence in underrepresented facilities such as local nature centers and science museums.

American Bullfrog (Lithobates catesbeianus) – Very Common*

The most common and most recognizable of the family. The bullfrog (as they are simply called here) is a big part of American culture, especially in the southeast where they are abundant. They are the second most reported amphibian here on iNaturalist; they are commonly eaten in parts of the country; they are frequently used for dissection in biology classes; and many keep them as pets. The survey found two dozen zoos and aquariums holding the species - including some major facilities - but there are quite a few more in hole-in-the-wall places across the country... and frankly, your odds of seeing a wild one in a zoo pond are decent too!

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Photographed in the wild by @ChunkyMunky pengopus

Leopard Frogs
Status in US Zoos: Common*

A number of species within the genus have been given this name due to the leopard-like spots on their skin. The two main species found in the survey were Northern Leopard Frog (L. pipiens) and Southern Leopard Frog (L. sphenocephalus). As with the bullfrog, the abundance was adjusted up for these frogs based on their prevalence in nature centers and the like, though they can be found in traditional zoos and aquariums a decent amount too.

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Southern Leopard Frogs; taken at Oklahoma Aquarium by @geomorph

Other species were picked up by the survey, all in numbers ranging from Uncommon to Rare; many of them are in small local facilities such as nature and science centers.

Plains Leopard Frog (L. blairi)
Gopher Frog (L. capito)
Green Frog (L. clamitans)
Pickerel Frog (L. palustris)
Wood Frog (L. sylvaticus)
Lowland Leopard Frog (L. yavapaiensis)
California Red-legged Frog (Rana draytonii)

Family Pyxicephalidae

African Bullfrog (or Pixie Frog) (Pyxicephalus adspersus) – Common

Nicknamed “pixie frog” for its scientific name rather than its appearance – as you’ll see from the photo below, its resemblance to pixies is lacking at best. This giant frog (9.5 inches long, weight 3 lbs) is also called a bullfrog, but is not part of the same family as American bullfrogs. With their bulbous body, stolid state and voracious appetite, they are a bit reminiscent of Pacman frogs – but are much larger and have a more uniform booger complexion rather than colorful patterning. They are common in the pet trade, where they presumably eat all of your other pets followed by your hand.

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Taken at San Diego Zoo Safari Park by @Zoological Point
 
Family Ranidae – “True Frogs”

The most stereotypical frogs: smooth skin, webbed feet, large and powerful legs, mostly aquatic. The family is found throughout the world, but all 10 species in the survey were native to the US; this is similar to Europe and Japan, which also hold primarily their own Ranidae. They are from either the genus Rana or Lithobates, depending on your taxonomy; zoos may sign them as either.

Note on the asterisks: I adjusted the abundance up from the actual survey numbers, based on their prevalence in underrepresented facilities such as local nature centers and science museums.

American Bullfrog (Lithobates catesbeianus) – Very Common*

The most common and most recognizable of the family. The bullfrog (as they are simply called here) is a big part of American culture, especially in the southeast where they are abundant. They are the second most reported amphibian here on iNaturalist; they are commonly eaten in parts of the country; they are frequently used for dissection in biology classes; and many keep them as pets. The survey found two dozen zoos and aquariums holding the species - including some major facilities - but there are quite a few more in hole-in-the-wall places across the country... and frankly, your odds of seeing a wild one in a zoo pond are decent too!

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Photographed in the wild by @ChunkyMunky pengopus

Leopard Frogs
Status in US Zoos: Common*

A number of species within the genus have been given this name due to the leopard-like spots on their skin. The two main species found in the survey were Northern Leopard Frog (L. pipiens) and Southern Leopard Frog (L. sphenocephalus). As with the bullfrog, the abundance was adjusted up for these frogs based on their prevalence in nature centers and the like, though they can be found in traditional zoos and aquariums a decent amount too.

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Southern Leopard Frogs; taken at Oklahoma Aquarium by @geomorph

Other species were picked up by the survey, all in numbers ranging from Uncommon to Rare; many of them are in small local facilities such as nature and science centers.

Plains Leopard Frog (L. blairi)
Gopher Frog (L. capito)
Green Frog (L. clamitans)
Pickerel Frog (L. palustris)
Wood Frog (L. sylvaticus)
Lowland Leopard Frog (L. yavapaiensis)
California Red-legged Frog (Rana draytonii)

Family Pyxicephalidae

African Bullfrog (or Pixie Frog) (Pyxicephalus adspersus) – Common

Nicknamed “pixie frog” for its scientific name rather than its appearance – as you’ll see from the photo below, its resemblance to pixies is lacking at best. This giant frog (9.5 inches long, weight 3 lbs) is also called a bullfrog, but is not part of the same family as American bullfrogs. With their bulbous body, stolid state and voracious appetite, they are a bit reminiscent of Pacman frogs – but are much larger and have a more uniform booger complexion rather than colorful patterning. They are common in the pet trade, where they presumably eat all of your other pets followed by your hand.

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Taken at San Diego Zoo Safari Park by @Zoological Point
Doesn't ASDM have Chiricahua Leopard Frog?
 
I believe the Arizona-Sonora Desert Museum breeds Chiricahua Leopard Frogs off exhibit, as does the Phoenix Zoo.
 
I believe the Arizona-Sonora Desert Museum breeds Chiricahua Leopard Frogs off exhibit, as does the Phoenix Zoo.
Aren't there some on-exhibit as well though? Or were on exhibit in the last couple of years at least? Or was it a different leopard frog species?
 
When I visited Phoenix Zoo in 2020, they had a Chiricahua Leopard Frog on-exhibit, it was in a tank behind a glass window in the conservation building. Had signage as well. Its been 3 years though, so it could be they're now no longer on display.

Another frog species missing is Pig Frog (Rana gryllio). I don't know any AZA zoos that have them, but two small nature centers near me in Florida do, Daggerwing and Green Cay. I've been to both within the last year so they're very likely still present.
 
Family Bufonidae – Toads
Part 1: Native Toads


It’s Toad Week! I’m going to break from taxonomy on this one and split toads into native and foreign. We’ll cover the natives first, all of which belong to three genera.

Puerto Rican Crested Toad (Peltophryne lemur) – Prevalent

Until very recently an active AZA breeding program for reintroductions, this species was thought to be extinct until it was rediscovered in the 1960’s. Hundreds of thousands of tadpoles bred in the continental US have been released into Puerto Rico since the project began; the species still remains endangered for the moment, however.

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Taken at Omaha's Henry Doorly Zoo by @bugboiben

Anaxyrus

Still sometimes lumped into the genus Bufo, the Anaxyrus toads make up the majority of wild toads in the US. The survey found 13 species in captive collections, representing about half the genus; most of these seem to be uncommon or rare. Zoos and aquariums generally hold species local to their area; additionally, many of these holdings will be nature centers or other collections focusing on local wildlife.

The most common species was American Toad (A. americanus), which was adjusted up to Common based on a missing data test; this was followed by Western Toad (A. boreas), which qualified as Prevalent (also adjusted up slightly).

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American Toad (A. americanus)
Taken at the Manitowoc Lincoln Park Zoo (Wisconsin) by @birdsandbats

Uncommon to Rare (varying from 1-6 holders found):

Wyoming Toad (A. baxteri) - Rare

This species was declared extinct in the wild in the 1990’s, and has since only been reintroduced to a single wildlife refuge in Wyoming. There is an active breeding and reintroduction program for this species, but not many individuals are on display.

Other Anaxyrus species:
Yosemite Toad (A. canorus)
Great Plains Toad (A. cognatus)
North American Green Toad (A. debilis)
Fowler’s Toad (A. fowleri)
Houston Toad (A. houstonensis)
Arizona Toad (A. microscaphis)
Red-spotted Toad (A. punctatus)
Sonoran Green Toad (A. retiformis)
Texas Toad (A. speciosus)
Southern Toad (A. terrestris)
Woodhouse’s Toad (A. woodhousei)

Incilius

The other genus of native toads in the continental US. Most species in the genus are from Mexico or further into the tropics, but all 3 species found in the survey are native here.

Colorado River Toad (Incilius alvarius)
Status in US Zoos: Prevalent to Common

Also called the Sonoran Desert Toad, this is the largest native toad in the United States at 7.5 inches long. It is found wild mostly in Arizona and is popular in American desert herp displays, often alongside lizards like Gila Monsters. This species is infamous for having psychoactive toxins that it exudes from the skin. Unfortunately this has led to the species being overcollected for drug extraction; the compound has now been illegal in the US for over a decade, and there are restrictions on collecting these toads from the wild or transporting them across state lines.

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Taken at North Carolina Zoo by @Breckenridge

And for scale, here are some toads next to a roadrunner:
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Taken at the Staten Island Zoo by @TinoPup

Other Incilius species:
Evergreen Toad (I. coniferus)
Gulf Coast Toad (I. valliceps)
 
Family Bufonidae – Toads
Part 2: Foreign Toads


The survey found 18 species of toad not native to the US. There are several species and one genus of note to cover, so this group will be split over two posts today and tomorrow.

Atelopus - Harlequin Toads

This is a genus of small, brightly colored, diurnal toads from the Neotropics. Many of these species have become rare or possibly extinct due primarily to chytrid fungus, along with other pressures like habitat loss. There were 6 species found in the survey, and most of you are probably familiar with one of them. The Dallas World Aquarium in particular has a lot of harlequin toads, holding all but 1 of the species in recent years - though the exact ones they have on exhibit seems to vary.

Panamanian Golden Frog (Atelopus zeteki) – Abundant (AZA only)

Surprised? Yes, the Panamanian Golden Frog - as it is normally labeled – is actually a toad (although toads are a kind of frog, so it’s not technically wrong). This critically endangered amphibian has not been seen in the wild since the 2000’s. It has the only formal AZA breeding program for a non-native amphibian, and the breeding program has been so successful that PGFs are now one of the most common amphibians in American zoos. They were also the most common species in the survey that is not kept in other major zoo regions, so that’s cool too.

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Taken at the National Aquarium in Baltimore by @jayjds2

Rio Pescado Stubfoot Toad (A. balios) - Rare

A critically endangered Ecuadorian species. Dallas World Aquarium was the first facility outside Ecuador to breed them in 2019, then somewhat suddenly two other zoos were reported to have them on display by 2022. A new rising star, perhaps?

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Taken at the Saint Louis Zoo by @d1am0ndback

Other species of Atelopus in US zoos (all Rare):
Purple Harlequin Toad (A. barbotini)
Elegant Harlequin Toad (A. elegans)
Hoogmoed’s Harlequin Toad (A. hoogmoedi)
Limosa Harlequin Toad (A. limosus)

Other Exotic Toads

Cane Toad (or Marine Toad) (Rhinella marina)

Status in US Zoos: Common to Very Common

Native to the Neotropics (and technically native, as it can be found naturally in the southern tip of Texas), this is a large toad at 4-6 inches in length - though the longest was nearly 10 inches. Cane toads have wreaked ecological havoc throughout other parts of the world after being introduced as a control on sugarcane pests. Unfortunately, Hawaii was one of those places... and yes, Florida too of course. Their toxins protect them from most predators, and have been used for purposes varying from poison arrows and leather to psychoactive drugs and medicines.

They are common as lab animals and in the pet trade, due to their abundance and relatively simple care needs. They are also a fairly popular species in zoos here, especially smaller and/or privately run zoos due to their widespread availability. I chose an Australian photo for this one… I feel like in this case it may even be appropriate!

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Taken at the Currumbin Wildlife Sanctuary (Australia) by @WhistlingKite24
 
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Worth noting, the frogs that are labelled as Panamanian golden frogs in AZA actually represent two species - the true Panamanian golden frog (A. zeteki) and a golden morph of harlequin frog (A. varius). The distinction between the two wasn't clearly understood at the time of the initial import (the Panamanian golden frog was once listed as a subspecies of harlequin frog, A. v. zeteki), but different studbooks are actually maintained to make sure that the two species don't hybridize.
 
Worth noting, the frogs that are labelled as Panamanian golden frogs in AZA actually represent two species - the true Panamanian golden frog (A. zeteki) and a golden morph of harlequin frog (A. varius). The distinction between the two wasn't clearly understood at the time of the initial import (the Panamanian golden frog was once listed as a subspecies of harlequin frog, A. v. zeteki), but different studbooks are actually maintained to make sure that the two species don't hybridize.
Interesting. Do we know what facilities keep which species?
 
Interesting. Do we know what facilities keep which species?
The vast majority in the US are zeteki. Holders of varius include Nashville, Cleveland, Denver, Detroit, Omaha, and John Ball, though some of those facilities also hold zeteki. All "Panamanian golden frogs" in the US, regardless of species, are owned by the Maryland Zoo in Baltimore
 
The vast majority in the US are zeteki. Holders of varius include Nashville, Cleveland, Denver, Detroit, Omaha, and John Ball, though some of those facilities also hold zeteki. All "Panamanian golden frogs" in the US, regardless of species, are owned by the Maryland Zoo in Baltimore
How do you tell the two species apart?
 
The vast majority in the US are zeteki. Holders of varius include Nashville, Cleveland, Denver, Detroit, Omaha, and John Ball, though some of those facilities also hold zeteki. All "Panamanian golden frogs" in the US, regardless of species, are owned by the Maryland Zoo in Baltimore

What are the visual clues between the two taxa?

~Thylo
 
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I believe golden varius are smaller and less well marked, but they are very similar, and II believe genetic testing was initially used to differentiate the two. I wouldn't trust myself to tell them apart at a glance, nor would many folks. Most zoos are only given frogs of one species or the other to reduce potential crosses, though some do have more than one. To give you an idea of how similar they can look, here's a facebook link to a post from Omaha that shows a golden varius (in AZA usually referred to as Marta or Rio Marta PGF)

Log into Facebook
 
The vast majority in the US are zeteki. Holders of varius include Nashville, Cleveland, Denver, Detroit, Omaha, and John Ball, though some of those facilities also hold zeteki. All "Panamanian golden frogs" in the US, regardless of species, are owned by the Maryland Zoo in Baltimore

Could the Maryland Zoo use a "panda diplomacy" strategy with Panamanian golden frogs for overseas zoos, such as those in the EAZA?
 
Thanks for adding all that context @Aardwolf. I'd known a little bit about that situation, but forgot to include it in the write-up and would not have been very knowledgeable about it even if I'd remembered.

I was aware that some zoos signed their frogs as A. varius, but I wasn't sure whether this was due to varius actually being present or due to outdated signage from when zeteki was considered a subspecies; all I knew for certain was that zeteki was present in large numbers. Additionally worth noting is that AZA has two distinct groups of zeteki, from two regional populations called "Ahogado" and "Sora". The use of these names alongside "Marta" made it unclear to me exactly what species each population was.
 
Family Bufonidae
Part 3: More Foreign Toads

Yellow-spotted Climbing Toad
or Asian Tree Toad (Rentapia hosii)
Status in US Zoos: Prevalent

Called by several different common names, this arboreal toad from Southeast Asia is decently common in the private trade. Of note: a recent split of hosii called R. flavomaculata seems to be the primary species now listed in the private trade, so some or all of the hosii might be the new species – but are not signed that way in zoos as of right now.

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Taken at Brookfield Zoo by @Semioptera

Asian Common Toad or Black-spined Toad (Duttaphrynus melanostictus)
Asian Giant Toad (Phrynoidis asper)

Status in US Zoos: both Uncommon

These two are both large Asian toads kept in a handful of zoos each, with varying common names (especially with D. melanostictus). Although the two look different – D. melanostictus is larger (~8 inches) and looks more heavyset (rather like a Cane Toad IMO), while P. asper is smaller (4-6 inches), leaner and more pebbly – the similar names and ranges makes checking the Latin on zoo signage an especially good idea for these. At least one facility – the California Academy of Sciences – holds a related species, the Borneo River Toad (Phrynoidis juxtasper).

Although the two have distinct physical differences, some of the gallery photos for these two species make them look rather similar; the two photos below were chosen to highlight the contrast as best I could.

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Duttaphrynus melanostictus; taken in the Netherlands by @vogelcommando

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Phrynoidis asper; taken in the United Kingdom by @Swampy

Kihansi Spray Toad (Nectophrynoides asperginis) – Rare

This tiny Tanzanian frog was once found in only a 5-acre area at the base of a jungle waterfall. The moisture that fed its habitat was drastically reduced when a dam was built there in 1999, and due to delays and issues recreating their habitat post-construction the frog hasn’t been seen in the wild since 2004. Fortunately, the Bronx Zoo began a captive assurance population three years prior and the toad is now maintained in the thousands between a small number of American zoos (not all of which display them).

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Taken at the Bronx Zoo by @TheoV

Other exotic Bufonidae found in the survey:

Uncommon:
Smooth-sided Toad (Rhaebo guttatus)

Rare:
African Green Toad (Bufotes boulengeri)
European Green Toad (Bufotes viridis)
Bumblebee Toad (Melanophryniscus stelzneri)
Rococo Toad (Rhinella diptycha)
Square-marked Toad (Sclerophrys regularis)
 
D. melanostictus is larger (~8 inches) and looks more heavyset (rather like a Cane Toad IMO), while P. asper is smaller (4-6 inches), leaner and more pebbly

Not sure where these figures came from, but definitely nor accurate- P. asper get a lot bigger than 6 inches, especially the females. Easiest way to distinguish these 2 is to look for the dark raised facial ridges that give D. melanostictus its species name.
 
Not sure where these figures came from, but definitely nor accurate- P. asper get a lot bigger than 6 inches, especially the females. Easiest way to distinguish these 2 is to look for the dark raised facial ridges that give D. melanostictus its species name.

Huh, interesting. Most sources I found on a cursory search specify that females are 95-140 mm (3.75 to 5.5 in) while males are 70-100 mm (2.75 to 4 in) - including AmphibiaWeb, which is where I got that number: AmphibiaWeb - Phrynoidis asper

I did find at least one source (Phrynoides asper (Phrynoidis asper) - JungleDragon) saying they can reach over 8.5 in; perhaps those are their maximum sizes, while the numbers I listed are average sizes?

You're definitely correct that the raised facial ridges for melanostictus is a consistent identifying feature, though - probably better than size or the other features I mentioned.
 
Fake Toads

Now that we’ve gone through the true toads, it’s time to end the week with a light post covering a couple posers.

Family Bombinatoridae – Fire-bellied Toads


Common in the private trade, these Eurasian toads are flat, warty, and red on the belly. The survey only found one species, which is also the one normally found in the pet trade here:

Oriental Fire-bellied Toad (Bombina orientalis) – Prevalent

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Oriental Fire-bellied Toad
Taken at Smithsonian National Zoo by @Andrew_NZP

Family Scaphiopodidae – Spadefoot Toads

These burrowing toads are round with bulging eyes. Most are found in arid climates, only coming out to breed during wet years. Overall they are quite rare in American facilities – the survey found a western species in three Southwestern zoos (two of which are native-focused facilities) and an eastern species in two aquariums.

Couch’s Spadefoot Toad (Scaphiopus couchii) – Rare
Eastern Spadefoot Toad (Scaphiopus holbrookii) – Rare


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Couch's Spadefoot Toad
Taken in the wild by @d1am0ndback
 
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