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

[ThylacineAlive]

A search of the forums for the genus shows the only American mentions to be at the Bronx Zoo in 2015 and 2019 (the latter saying that they were no longer there [or not on display]).

So having now seen Hymenochirus in the pet trade, I am confident the Bronx animals have never been of this genus. The last confirmed dwarf clawed frog at the Bronx I could find was in the 2000's... The zoo has been and continues to keep X. tropicalis with the incorrect label for H. boettgeri. As the zoo has improved on their signage in most of their other houses, I would really like to see CGF get an update.

~Thylo

 

[Coelacanth18]

Family Hylidae – Tree Frogs
Part I: Native Tree Frogs

The main tree frog family is quite large, and by some taxonomies all 3 of its subfamilies could be considered separate families. As stated before, I’m not a taxonomy expert - so I'll cover them by "group", with no opinion on exactly how related they are.

Today we'll start with the native tree frogs from subfamily Hylinae. Thought tree frogs were a specialty of the tropics? Think again: 9 native species were found in the survey.

Dryophytes
These represent most native tree frogs in the US. They are particularly abundant in the woodlands and wetlands of the southeast (where I’ve seen one or two myself) and I’m sure several ZooChatters have heard them calling at night.

American Green Tree Frog (D. cinereus) – Prevalent to Common
Gray Tree Frog (D. versicolor) – Prevalent to Common
Cope’s Gray Tree Frog (D. chrysoscelis) – Uncommon

The Green and Gray Tree Frogs account for the majority of holdings in this genus, and appear to be held exclusively in the eastern half of the country where they are found wild. Despite the simple common names, all three of these species are variable in color – Greens can be brown, Grays can be green, etc. They are primarily nocturnal, and evening/nighttime is when you are most likely to stumble upon one.

While American Greens are usually easier to distinguish – they are smooth, slender and normally bright green – the two Gray Tree Frogs are virtually impossible to distinguish visually: both have warty-looking skin, and variable color that trends toward a marbled mix of gray and very pale green. Rangewise versicolor is primarily in the north and chrysoscelis is primarily in the south, but there is at least some overlap on the edge. Their calls are different – Cope’s tends to be shorter and faster – but this is also dependent on temperature. Aren't frogs fun?

American Green Tree Frogs / Taken at Cincinnati Zoo by @Moebelle

typical Gray Tree Frog (D. versicolor)
Taken at Powder Valley Nature Center (Missouri) by @cloudedleopard611

green Gray Tree Frog (D. versicolor) / Taken at Sedgwick County Zoo by @Ituri

Barking Tree Frog (D. gratiosus) - Uncommon to Rare
Squirrel Tree Frog (D. squirrellus) - Uncommon to Rare

Two southeastern tree frogs; the first has thick and leathery skin, while the second looks very similar to the American Green.

Pacific Tree Frog (Pseudacris regilla) – Uncommon
Canyon Tree Frog (Dryophytes arenicolor) – Rare

The two western tree frogs found in the survey. The Pacific is found up the West Coast from California to Alaska, while the Canyon is found in the interior Southwest.

Pacific Tree Frog / Taken in the wild by @Great Argus

Other native tree frogs found in survey (Rare):

Blanchard’s Cricket Frog (Acris blanchardi)
Spring Peeper (Pseudacris crucifer)

Tomorrow we'll start on the tropical tree frogs, which will pad out the rest of the week.

 

[birdsandbats]

Family Hylidae – Tree Frogs
Part I: Native Tree Frogs

The main tree frog family is quite large, and by some taxonomies all 3 of its subfamilies could be considered separate families. As stated before, I’m not a taxonomy expert - so I'll cover them by "group", with no opinion on exactly how related they are.

Today we'll start with the native tree frogs from subfamily Hylinae. Thought tree frogs were a specialty of the tropics? Think again: 9 native species were found in the survey.

Dryophytes
These represent most native tree frogs in the US. They are particularly abundant in the woodlands and wetlands of the southeast (where I’ve seen one or two myself) and I’m sure several ZooChatters have heard them calling at night.

American Green Tree Frog (D. cinereus) – Prevalent to Common
Gray Tree Frog (D. versicolor) – Prevalent to Common
Cope’s Gray Tree Frog (D. chrysoscelis) – Uncommon

The Green and Gray Tree Frogs account for the majority of holdings in this genus, and appear to be held exclusively in the eastern half of the country where they are found wild. Despite the simple common names, all three of these species are variable in color – Greens can be brown, Grays can be green, etc. They are primarily nocturnal, and evening/nighttime is when you are most likely to stumble upon one.

While American Greens are usually easier to distinguish – they are smooth, slender and normally bright green – the two Gray Tree Frogs are virtually impossible to distinguish visually: both have warty-looking skin, and variable color that trends toward a marbled mix of gray and very pale green. Rangewise versicolor is primarily in the north and chrysoscelis is primarily in the south, but there is at least some overlap on the edge. Their calls are different – Cope’s tends to be shorter and faster – but this is also dependent on temperature. Aren't frogs fun?

American Green Tree Frogs / Taken at Cincinnati Zoo by @Moebelle

typical Gray Tree Frog (D. versicolor)
Taken at Powder Valley Nature Center (Missouri) by @cloudedleopard611

green Gray Tree Frog (D. versicolor) / Taken at Sedgwick County Zoo by @Ituri

Barking Tree Frog (D. gratiosus) - Uncommon to Rare
Squirrel Tree Frog (D. squirrellus) - Uncommon to Rare

Two southeastern tree frogs; the first has thick and leathery skin, while the second looks very similar to the American Green.

Pacific Tree Frog (Pseudacris regilla) – Uncommon
Canyon Tree Frog (Dryophytes arenicolor) – Rare

The two western tree frogs found in the survey. The Pacific is found up the West Coast from California to Alaska, while the Canyon is found in the interior Southwest.

Pacific Tree Frog / Taken in the wild by @Great Argus

Other native tree frogs found in survey (Rare):

Blanchard’s Cricket Frog (Acris blanchardi)
Spring Peeper (Pseudacris crucifer)

Tomorrow we'll start on the tropical tree frogs, which will pad out the rest of the week.

I do wonder how many of the Gray Tree Frogs out there are correctly identified to species - it would be very easy to have D. versicolor and think you have D. chrysoscelis or vice versa. The entire state of Wisconsin is within the overlap zone for those two species, and pretty much every nature center some of them, and they are ALWAYS signed as D. versicolor. I wonder how often that's actually the case.

 

[Coelacanth18]

I do wonder how many of the Gray Tree Frogs out there are correctly identified to species - it would be very easy to have D. versicolor and think you have D. chrysoscelis or vice versa. The entire state of Wisconsin is within the overlap zone for those two species, and pretty much every nature center some of them, and they are ALWAYS signed as D. versicolor. I wonder how often that's actually the case.

Yeah I wonder that myself; hypothetically you could do it by call, but I don't know if zoos actually do that or if they base their ID on something else. I didn't find any facility that displayed both, so I guess their word is all you have to go on usually.

 

[TinoPup]

To complicate things, they can hybridize. Maritime Aquarium has one that they think is likely a hybrid. Exhibited with gray tree frogs and tiger salamanders.

 

[Coelacanth18]

To complicate things, they can hybridize. Maritime Aquarium has one that they think is likely a hybrid. Exhibited with gray tree frogs and tiger salamanders.

View attachment 612360
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That is interesting - and you could be right about the possibility of Dryophytes hybrids - but for clarification that signage is for a hybrid toad rather than tree frog, correct?

 

[TinoPup]

That is interesting - and you could be right about the possibility of Dryophytes hybrids - but for clarification that signage is for a hybrid toad rather than tree frog, correct?

I'm not actually sure! It says toad, but everything else in there is a tree frog.

 

[birdsandbats]

That is interesting - and you could be right about the possibility of Dryophytes hybrids - but for clarification that signage is for a hybrid toad rather than tree frog, correct?

I'm not actually sure! It says toad, but everything else in there is a tree frog.

I'm guessing it's an old sign for a hybrid toad and the tree frog is unrelated - the two species have different chromosome counts so hybridization seems unlikely.

 

[15399]

I'm guessing it's an old sign for a hybrid toad and the tree frog is unrelated - the two species have different chromosome counts so hybridization seems unlikely.

Although differing chromosome counts hasn't stopped hybridization before- with mules being perhaps the most classic example. Oftentimes, such as in mules, conflicting chromosome counts do mean the offspring are infertile, but that doesn't stop them from being produced.

 

[TinoPup]

I'm guessing it's an old sign for a hybrid toad and the tree frog is unrelated - the two species have different chromosome counts so hybridization seems unlikely.

They're not entirely sure what it's a hybrid *of*, they received it as a tadpole.

 

[birdsandbats]

They're not entirely sure what it's a hybrid *of*, they received it as a tadpole.

The picture depicts a toad, and I see no reason to suspect the frog in the image is a hybrid in the first place. It looks identical to any Eastern or Cope's Gray Tree Frog.

 

[Coelacanth18]

I see no reason to suspect the frog in the image is a hybrid in the first place. It looks identical to any Eastern or Cope's Gray Tree Frog.

Although as we established, Eastern and Cope's already look identical to each other... so a hybrid would look like that, if one were to exist

The discussion of hybrids is interesting, though. From my research they're fairly uncommon in public collections, but it might be worth doing a bonus post about notable hybrids or crosses. I'm already planning on doing some "bonus content" posts for topics broader than specific herp groups, but that was one I hadn't considered until now.

 

[TinoPup]

The picture depicts a toad, and I see no reason to suspect the frog in the image is a hybrid in the first place. It looks identical to any Eastern or Cope's Gray Tree Frog.

I'm going to trust the institution over someone looking at a single photo.

 

[Chlidonias]

I'm going to trust the institution over someone looking at a single photo.

But the picture of their sign is clearly showing a toad and not a tree frog, and the sign clearly refers to it being a hybrid toad and not a tree frog. There is nothing about the sign to connect it to tree frogs.

 

[Gondwana]

Regarding the two gray treefrog species, they absolutely can hybridize, producing triploid offspring that are less likely to reach adulthood and generally sterile if they do fully develop.

 

[Coelacanth18]

Now that you know what tree frogs are in both your backyard and local zoo/nature center, let’s take a look at some of the jungle tree frogs from the equatorial Americas.

Subfamily Hylinae

Amazon Milk Frog (Trachycephalus resinifictrix)
Other Names: Mission Golden-eyed Tree Frog
Status in US Zoos: Abundant

This frog is a sleeper hit, or at least was for me; it was the 11th most common species in the survey, and the most common amphibian that wasn’t a dart frog. They are overwhelmingly in both larger and smaller AZA zoos and aquariums specifically, although they are also fairly common in the private trade. A fairly large tree frog at up to 4 inches, they are a light gray-green with brown banding. Their name comes from their milky skin secretions they produce when stressed.

Taken at Zoo Miami by @Andrew_NZP

Cuban Tree Frog (Osteopilus septentrionalis)
Status in US Zoos: Prevalent

Another large tree frog, this one from the Caribbean. It is more nondescript, varying in color but usually being some kind of green or brown. They are invasive in Florida – or as we should all be calling it, Pantropica.

Taken at Sedgwick County Zoo by @Ituri

Subfamily Phyllomedusinae – Leaf Frogs

Our other group of Neotropical tree frogs. Most of these are smaller and more slender than the previous two species - but those I'll leave for tomorrow's post. Today we'll cover the biggest frog in American collections from this subfamily.

Phyllomedusa – Waxy Monkey Tree Frogs
Status in US Zoos: Prevalent

Called various names using a combination of the words “waxy”, “monkey”, and/or “tree”, the Phyllomedusa are comical to look at; they perch on branches like a monkey, often with their long digits crossed as if in anticipation. They are a solid leaf-green color - often with distinct ridges outlining their back - and are similar in size to the Amazon Milk Frog. There are at least two species kept in US collections, P. bicolor and P. sauvagii; the first seems to be the majority, but I couldn’t confirm almost half of the survey holdings because they both use the same common name.

Taken at Houston Zoo by @snowleopard

Taken at ZSL London Zoo by @gentle lemur

 

[Coelacanth18]

Leaf Frogs (Subfamily Phyllomedusinae)

Red-eyed Tree Frog (Agalychnis callidryas) – Common

The second most common tree frog in zoos after Amazon Milk Frog, everybody knows these: gangly, bright red bug eyes, neon green with blue and yellow stripes and clownishly orange toes. Found in lowland rainforests of Central America, these are also popular pets. Despite their eye-catching appearance, they are nocturnal and most captive specimens will spend the day with their back to us, camouflaged on a green leaf. Or they’ll stick to the glass wall like this:

Taken at Virginia Zoo by @TinoPup

The best shots I found for this species are not American, so I chose this wild animal photographed by a Brit. Does this make up for all the tea we chucked in the harbor?

Taken in Costa Rica by @Newzooboy

Mexican Leaf Frog (Agalychnis dacnicolor) – Prevalent

A relative to the red-eyed tree frog, this species hails from drier forests along the Pacific coast of Mexico. It is much blander in color than its cousin, generally being a solid shade of green with white specks on the back. It is also stockier than callidryas.

Taken at the Arizona-Sonora Desert Museum by @Ituri

Lemur Leaf Frog (Agalychnis lemur) – Prevalent

This critically endangered tree frog is from the mid-level elevations of Costa Rica and Panama, and has been an unfortunate victim of the chytrid fungus that wrecked many amphibian populations in that region. They are shyer than the other two Agalychnis species, making them a real treat to see when they can be found.

Taken at Detroit Zoo by @jayjds2

Cruziohyla Leaf Frogs
Status in US Zoos: Uncommon

Two of these slender Neotropical frogs were found in the survey. I brought these up because one of the species – Cruziohyla calcarifer – is sometimes called the Splendid Tree Frog rather than Splendid Leaf Frog. This isn’t wrong (they do live in trees) but it may cause confusion as American zoos carry a different species often called Splendid Tree Frog, Litoria splendida. If you see a smaller, slender flat frog labeled “Splendid” it’ll be this species, seen here:

Splendid Leaf Frog
Taken at the National Aquarium in Baltimore by @jayjds2

Species:
Splendid Leaf Frog (C. calcarifer)
Fringed Leaf Frog (C. craspedopus)

The following is a list of all the Hylinae and Phyllomedusinae species found in the survey that didn't get covered yet:

Uncommon
Hourglass Tree Frog (Dendropsophus ebraccatus)

Rare
Gliding Tree Frog (Agalychnis spurrelli)
Map Tree Frog (Boana geographica)
Clown Tree Frogs (Dendropsophus leucophyllatus and sarayacuensis)
Hispaniolan Tree Frog (Osteopilus dominicensis)
Tiger-legged Monkey Frog (Pithecopus hypochondrialis)
Masked Tree Frog (Smilisca phaeota)
Veined Tree Frog (Trachycephalus typhonius)
Coronated or Spiny-headed Tree Frog (Triprion spinosus)

Tomorrow will be the last group of Hylidae - the Australian tree frogs.

 

[Coelacanth18]

Australian Tree Frogs (Subfamily Pelodryadinae)
Genus Ranoidea or Litoria (depending on taxonomy)

White’s Tree Frog (R. caerulea) – Common

Also called the Australian Green Tree Frog, but usually referred to in the States as either White’s or dumpy tree frog. These cute, 4-inch tree frogs are common in Australia, showing up on windowsills and inside homes (and toilets). They are one of the most popular pet frogs for several reasons: they’re very docile, they live longer than most frogs, they can eat a variety of things, and they’re hardy – very hardy. This hardiness may have to do with their skin secretions making them resistant to diseases, including chytrid fungus.

I couldn’t find a great representative photo from the American galleries, so here’s one from Germany.

Taken by @ronnienl at the Berlin Zoo-Aquarium

Magnificent Tree Frog (R. splendida) – Prevalent

Another bulbous tree frog from Australia. This one comes from the northwest portion of the island continent, where it hides in caves and crevices during the day to keep from drying out. It has yellow spots and is a similar size to the White’s. It is also called Splendid Tree Frog in line with its Latin name - though again, don’t confuse this with the Cruziohyla leaf frog that is sometimes called the same thing.

Taken at the Los Angeles Zoo by @Ding Lingwei

The third species found in the survey was Orange-eyed Tree Frog (R. chloris), which is Rare to Uncommon with only a handful of zoos displaying them (for now – Los Angeles sure seems to be cranking them out). They're often (usually?) called Red-eyed Tree Frogs in Australia - so don't confuse them with the Red-eyed Tree Frog we're used to that's a leaf frog

Taken at the SEA LIFE Sunshine Coast Aquarium in Australia by @WhistlingKite24

 

[SusScrofa]

Another species present thats not mentioned is Mexican Brown Tree Frog (Smilisca baudini). Held in Jacksonville as of a couple months ago.

 

[Coelacanth18]

Only two posts this week, mainly so I can devote four consecutive days to the next group of frogs.

Family Rhacophoridae

Shrub frogs, moss frogs, bush frogs, tree frogs – whatever you want to call them, their time to shine has come! While most species from this predominantly Asian frog group are arboreal, they’re not closely related to the tree frogs from last week.

Vietnamese Mossy Frog (Theloderma corticale) – Common

Also called the Tonkin Bug-eyed Frog, but why? It looks like moss, and frankly I think it should be prouder of that than its bug eyes. From Southeast Asia, this camouflaged jungle frog is a fairly common sight in American collections.

Taken at the Tennessee Aquarium by @geomorph

From the same genus is the infamous Bird Poop Frog (Theloderma asperum), whose name and camouflage method are both self-explanatory. The Mystic Aquarium in Connecticut is the only place I found this unusual species, surprisingly. Below is a photo of a wild individual.

Wild; taken in Thailand by @Swampy

Borneo Eared Frog (Polypedates otilophus) – Prevalent

Also called the File-eared Tree Frog, the conspicuous bony crest above the ear lends its name to this vaguely leaf-looking amphibian.

Taken at the Houston Zoo by @DannySG

Flying Frogs
Status in US Zoos: Rare

You’d think such a cool amphibian would be more common, but only 2 species showed up in 3 zoos since 2018. They aren’t particularly more common in Europe either, except in Poland and Russia for some reason. Many Japanese zoos and aquariums hold them, as a couple of species are native there.

Species:
Wallace’s Flying Frog (Rhacophorus nigropalmatus)
Chinese Flying Frog (Zhangixalus dennysi)

Taken at the Toledo Zoo by @Moebelle

Other Species in Rhacophoridae:
Cinnamon Tree Frog (Nyctixalus pictus) – Rare