Music of the Night

Written by Tyler Parker

Since it’s almost Valentine’s Day we here at the Zoo would be remiss if we didn’t talk about how amphibians find that special someone.
Amphibians are probably the most commonly heard vertebrate on the planet and this is due to the wonderful chorus that frogs and toads provide every year in the spring and summer, at least in North America.

frog blog1

Each year large groups of males congregate at perennial or vernal pools, ponds, or streams and sing for their mate. The larger the chorus of bachelor frog the more attractive it is for the ladies. Yet, even if multiple different species of frogs or toads are calling at one pond, each species of frog and toad have their own unique and identifiable call. This is how many researchers calculate populations of amphibians by listening to each individual species chorus and count the number of males calling.

This bombastic strategy isn’t the only way amphibians find their mates. Some frogs and toads are unable to call loud enough due to other noise in their environments such as fast moving streams or rivers. These frogs and toads employ the strategy of semaphoring, which is basically flagging or waving of either their front or back legs to stake claim to a territory or attract a mate.

Salamanders and caecilians utilize chemicals called pheromones to attract a potential mate.  Newts attract mates via a skin color change or a physical change in body shape often, with males developing very prominent crest or dorsal appendages.

In all, amphibians utilize a wide variety of ways to attract a special someone, yet all are unique and amazing in their own right.

Extreme Amphibians

Written by Tyler Parker

Amphibians are an extreme and versatile group of animals. They come in three main body types yet they exhibit some extreme variation in size, shape, and function.


The largest frog or toad in the world is the Goliath frog (Conraua goliath) native to West Africa.  This frog measures in at 12.6 inches and weighs up to 7.17lbs. The Goliath frog is followed in sized by the Cane Toad (Rhinella marina) and African Bullfrog (Pyxicephalus adspersus).  Yet the world’s biggest amphibian title is held by the Chinese Giant Salamander (Andrias davidianus). This behemoth comes in at a whopping 5.9ft long and weighs in at a hefty 110 lbs. Though its size may be impressive, it has made it a target in its native China as a popular luxury food item and its use in Traditional Chinese Medicine (TCM).  The world’s smallest amphibian Paedophryne amauensis (no common name given yet) from Papua New Guinea, also holds the title of the world’s smallest vertebrate.  Measuring in at an incredibly small 0.30 inches it beat out the current record holder, a fish from Indonesia by 0.0079 inches. This amazing amphibian can fit very comfortably inside the diameter of a dime.

Photo credit: Christopher Austin, Louisiana State University via National Geographic
Paedophryne amauensis – Photo credit: Christopher Austin, Louisiana State University via National Geographic


Amphibians come in many extreme shapes, all of which help them to survive in their natural habitat.  The most unknown group of amphibians has to be the caecilians; in appearance they look like scale less snakes or large segmented worms. This is augmented by the fact that most subterranean caecilians, have no or small vestigial eyes and weird tube like tentacles that come out of their nose.  Caecilians aren’t the only amphibians that look extreme though, take the Indian purple frog (Nasikabatrachus sahyadrensis).  This frog is again almost completely subterranean; it even eats underground, yet when the monsoons come to the Western Ghats of India these frogs surface to call and mate in the fast moving rivers and streams that are formed from the rains.

Photo credit: SD Biju, University of Delhi via National Geographic
Indian Purple Frog – Photo credit: SD Biju, University of Delhi via National Geographic


giant waxy monkey tree frog
Giant Waxy Monkey Frog

Though size and shape are an extreme in which we categorize amphibians, others in this order are equally extreme in the way in which they behave and survive in their natural habitats while dealing with extreme conditions.  Spadefoot toads cocoon under the ground in the deserts until the rains return and it is incredible that amphibians survive up north where it is cold almost 6 months out of the year. How do they do it? The North American wood frog (Lithobates sylvaticus) handles this situation by allowing itself to freeze solid by protecting its blood and vital organs with anti-freezing peptides produced by it and from the prey it eats.  The same is true of frogs that are exposed to extreme heat yet have no means to escape it by burrowing.  The giant waxy monkey tree frogs (Phyllomedusa bicolor) are able to produce their own natural sunscreen and wipe it all over their bodies to prevent drying out through desiccation.  Finally what’s more extreme than an animal that doesn’t breathe on land using lungs?  There is a whole family of salamanders called Plethodontidae that don’t have any lungs at all.  They breathe through their skin exclusively and are one of the largest families of salamanders in the world.  The most amazing thing is most of these salamanders are located here in the United States.

It’s extremely incredible how diverse amphibians are.


What Exactly is an Amphibian?

amazon milk frog
Amazon Milk Frog

Before we get to that, let me throw this out there.  There are five taxonomic classes of vertebrate (having an internal skeleton) animals.  These are fish, amphibians, reptiles, birds, and mammals.  Historically, amphibians and reptiles have been grouped together, often resulting in confusion as to what each group contains.  Amphibians include frogs and toads, newts and salamanders, and caecilians.  Crocodilians, lizards, snakes, turtles, and tortoises are reptiles.

Houston Toad
Houston Toad

The words “frog” and “toad” are not strict definitions.  In general, frogs have smooth skin and are more likely to stay close to water, while toads usually have dry bumpy skin and can be found further from water.  Also, frogs jump and toads do cute little hops.  Same deal with “newt” and “salamander.”  Newts are a kind of subgroup of salamanders and are usually aquatic as adults.  The third kind of amphibian that you’ve probably never heard of is the caecilian.  These look basically like large earthworms and most are burrowers so aren’t seen very often.  Some are quite colorful and one can even grow to almost 5 feet!

Photo credit: Dante Fenolio
Caecilia species Loreto Peru. Photo credit: Dante Fenolio

So that is what amphibians are.  Stay tuned over the next few weeks of “Amphibian Month” to learn some interesting, and some downright weird things about them.

Discover What Makes the Houston Toad So Unique

IMG_9112The Houston Zoo is excited to welcome a new intern who comes to us all the way from Kenya, in East Africa. Gilbert Sabinga is in the United States as participating in the Community College Initiative Program (CCIP). The Community College Initiative Program is a program of the U.S. Department of State, administered by Northern Virginia Community College on behalf of the Community College Consortium (CCC) in partnership with Houston Community College. While participating in this program, he will join us at the zoo as an intern to learn all about what a modern-day zoo is like! Sabinga is already part of the conservation community as he has been working with Save the Elephants in Kenya for over 8 years. He will be documenting his experiences at the Zoo and we will share his thoughts with you here on our blog!

Sabinga writes:

Sabinga blogHouston Zoo is the nature in it’s wildest. Every day coming to the zoo it offers me a new chance to get up close from wildlife around the world, and learn close facts about the animals. This time I was introduced to toads!!!! The little I knew about the toads is valuable part of our outdoor heritage. Most of people probably don’t give them much thought, and rarely credit what we consider lesser life not with emotions big as ours; but we need these amphibians to control destructive insects and to offer their voices to the sounds of spring and summer nights. Just hearing or seeing them adds to our enjoyment of outdoor joy and makes our environment beautiful. I visited and got to help in the toad department under the instruction of Tyler Parker, who never get tired of me asking questions about toads. He really taught me much on toads and expanded my knowledge about the toads especially Houston toads.

Sabinga blog2Today, with species threatened and habitats disappearing worldwide, the Houston Zoo  is playing a new role in conservation: the Zoo is expanding their efforts far beyond keeping animals alive in captivity. An example of this is the toad quarantine facility that serves as a location for captive breeding and head- starting of Houston toads eggs stand for release in to the wild, and this facility is managed full-time by Houston toad specialists who care for the toads and work closely. I never thought of how great this is wow! Credit to toad keepers.

The best part is that we would all love to think that wild animals in reality are at least a little bit like they are in National Geographic movies – cute, cuddly and happy to be in human company. Certainly toads can get used to human caretakers. Dr. Lauren Howard held one told and I was surprised that the toad did not struggle and even closed its eyes! I was wondering is it love? Or, the warmth of Lauren’s hand, or cues from the toad that it enjoys the care.  We all need to care for these magnificent local Texas creatures.

Sabinga blog3
Amphibian species are now on the verge of extinction. How do we save them?

– Toads like to take their time crossing the road…give them a brake! Roadkill is a significant cause of toad and frog mortality in many parts of the world. So drive slower on wet nights. Help a frog or toad cross the road (careful: don’t cause an accident or get squashed yourself).

– If you are building a pond, and want to support a healthy toad community, do not stock fish in it–even native species. Fishless ponds always tend to have a higher amphibian biodiversity than do ponds with fish.

– Most of the products we use in our daily life, and even the things we take for granted (food, water, electricity) have been removed from their natural place in the environment. We therefore offer the following suggestions on how you can reduce your ecological footprint: Turn off your air conditioning when it’s not in use. Take a shorter shower. Put a lid on that pot of boiling water. Turn off your lights. Print on both sides of the sheet of paper. Turn your jacuzzi off when it’s not in use. Going for a picnic? Don’t use styrofoam plates; most supermarkets sell biodegradable corn plates.

For more information visit;

Point to remember; Toads may be begging for their environmental freedom!!!

Why wait for Easter for an “egg-travaganza?!”

The Houston toad team at the Houston Zoo has been working up a storm this spring – a storm of Houston toad eggs! As of this writing, the team has bred 23 groups of adult Houston toads (the groups consist of either one female and one male or one female and two male) since the middle of February using assisted breeding methodologies. In total, we have produced ~80,000 Houston toad eggs!! This is more than twice as many as we produced last year and is a tremendous success for our program!! However, I’m sure you are all wondering just what in the world are we doing with all of those eggs??


Each and every one of the Houston toad egg strands produced at the Zoo going back to the wild to help augment the wild population.  Researchers from Texas State University (TSU) are strategically placing the egg strands in two counties, Austin County and Bastrop County, which are in the historic range of the Houston toad. Both of these counties still harbor small, wild populations of Houston toads that are being monitored by TSU and USFWS.

Researchers from TSU and Houston toad staff and interns are placing the eggs inside protective, wire cages as the strands are placed into the release ponds. Cages? What are those for? One of the biggest complications for the Houston toad recovery effort is that everything LOVES to eat Houston toads – especially their eggs! Birds, fish, aquatic invertebrates, raccoons, you name it; they all love to snack on tasty toad eggs. The cages prevent these hungry critters from feasting on these precious, endangered egg strands, helping to ensure that many of these eggs will survive to make tiny toadlets!

TSU researchers are monitoring each of the release sites and are on the lookout for Houston toad tadpoles and metamorphs. Are the cages working? Are the eggs going to hatch? Stay tuned to find out!

We’re Not Just Toad Keepers, We’re Matchmakers!

The Houston toad team spends countless hours performing the traditional tasks associated with caring for animals.  These tasks includes the cleaning, feeding, medical treatments of the Houston toads, as well as  water quality testing, care of the invertebrate cultures, and the general maintenance of the toad facility. However, did you know that the team is also responsible for being toad “match-makers” during the breeding season? Yup, that’s right. Not only are we handy with pH testing strips and power drills, we can also provide professional dating recommendations to Houston toads (now try writing that up on YOUR résumé!)

toad blog feb

Like many other endangered species, the breeding of Houston toads is managed a Species Survival Plan (SSP), which is a document produced by the Association of Zoo and Aquarium’s Population Management Center. The SSP takes into consideration the known genetics of a group of animals and makes recommendations as to who the animals should be paired with.  With these guidelines in hand, the Houston toad team evaluates each individual toad from a group of toads approved for breeding, and assesses their health and size. Breeding pairs (or triplets, often one female and two males) are then grouped accordingly. This year we evaluated and paired over 170 individual toads!

toad blog feb 2

Breeding Houston toads is not as easy as placing a male and female toad together. In fact, it is very difficult (but not impossible) to encourage natural breeding captive environments. Here in the toad facility, we use a hormone assisted breeding protocol to ensure successful breeding in our Houston toads. This protocol takes place over the course of several days, and requires a concerted effort between the Houston toad team and the zoo’s veterinary staff.

It would be impossible to breed all 170 toads at one time, so this spring we are staggering the breeding attempts over the course of two months and setting up 6-8 breeding pairs a week. We are happy to announce that our first round of breeding (that ironically began on Valentine’s Day) was a huge success! Out of the 8 total pairings set up, we produced 7 strands which totaled around 27,000 eggs!

So now that our matchmaking efforts were a success, what’s next? Stay tuned to the next blog post to find out what we are doing with all those toad eggs!

Finding the Wily, Wild Houston Toad!

While many of us are enjoying these cool, winter evenings indoors in front of the TV with our favorite snack, Houston toad researchers are bundling up, grabbing a thermos of coffee and hitting the road to find the  elusive Houston toad! After the first heavy rain of the year, often near the end of January, Houston toads are hitting the ponds to look for mates.  The Houston toad spends the majority of the year in shallow burrows to escape the extreme Texas temperatures (a process called estivation); therefore the best opportunity to find and count toads is during their breeding season when they are out and about.

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Houston toad male calling

Though some toad biologists slip on a pair of rubber boots and put on a headlamp to look for Houston toads using sight, most researchers search for toads using sound. Sound? How does that work? The Houston toad males have a very distinctive advertisement call, which is the call that they use to tell female toads “Hey, lady! Check me out! I’m over here!” In fact, all species of frogs and toads have a distinctive call that they use to get the attention of the opposite sex. Interestingly, it is not just the males that do the calling. In some species, including another local frog species called the gray tree frog (Hyla versicolor), the females will both call and counter-call (which means to call back) to the males. To hear a Houston toad call, check out the following link:


USFWS biulogists depolying a SongMeter

To find calling toads, researchers set out in their cars after dark to literally “listen” for Houston toads. The areas that are visited have been previously identified as suitable habitat for the Houston toad, or are locations where Houston toads were either found or heard in the past. The surveys follow a very systematic pattern with dozens of stops, and they often take hours to complete. This year, for the first time in several years, five Houston toad counties are being surveyed at once lead by research teams from Texas State University and USFWS. Fingers crossed that we’re going to find some wild toads!

Another way that researchers find wild Houston toads is through the use of a recording device called a SongMeter. A SongMeter is specifically designed to detect the auditory calls of wild animals.  To detect Houston toads, SongMeters are placed in trees near ponds and are programmed to record sounds during the course of the night. These devices can record two weeks’ worth of sound data! A software program is then used to find the particular waveform that correlates to the Houston toad call. Of course, every Houston toad “hit” found by the software program has to be verified by human ears, which requires hours of listening time.

So over the next couple of months while you’re enjoying your favorite evening TV show, take a moment to think about the field researchers braving the chilly, wet Texas nights on the hunt for the Houston toad. Each toad found (or heard) tells us more about the health of the wild population and gives us another critical piece of information concerning the natural history of this rare species. Good luck toad folks and Godspeed!

It's Houston Toad Time!

The toad team at the Houston Zoo hopes that everyone had a wonderful winter holiday. Like a lot of people, we have also made some “resolutions” for 2014; however, they don’t involve hitting the gym or finding a hot date!  Instead, we have resolved to release thousands of Houston toad eggs into the wild in and around Bastrop State Park this spring – how about that?!

Houston toad eggs.

While most amphibians are still tucked away in their winter hiding places, the Houston toad is getting ready for the breeding season. The Houston toad breeding season typically starts in late January or early February and can last until the first of May depending on rainfall.  The first heavy rains of the year generally signal the start of the breeding season and though it is pretty cold this time of year, as long as the nighttime air temperature is around 50F, the toads will come to the pond to find a mate!

Just like the wild toads, we are also gearing up for breeding season here at the Houston Zoo.  Like many endangered species that are bred at zoos, the Houston toad program has a breeding plan (called a Species Survival Plan, or SSP) that was designed by toad biologists and the Association of Zoos & Aquariums’ Population Management Center.  Using this plan, specific groups of toads are selected to breed with each other to ensure genetic diversity.

Because we are a release program, we have to make sure that each individual toad is free of any potential pathogens that could be passed to the eggs and then spread out into the wild.   We started an extensive disease screen in October of 2013, and to date we have cleared 90% of our breeder toads!


Interestingly, the weather plays a huge role in our breeding schedule. It would be silly to produce thousands of toad eggs, then not have any ponds to place them in! We very carefully watch the weather before we decide to breed and release eggs. In fact, because the weather and environmental conditions are so critical, we heavily rely on field researchers from Texas State University and USFWS to help us make the decision to breed. Everyone please continue cross your fingers for rain, the Houston toads need it!

The Houston Zoo and our collaborators at the Fort Worth Zoo, Dallas Zoo, Texas State University, and USFWS are gearing up for a huge release of Houston toad eggs this year.  This concerted effort has never been attempted before, but we are excited and ready for the challenge! Could 2014 be the year of the Houston toad? Stay tuned to find out!

The Little School Raises $3000 For Wild Frogs

I am always impressed with the drive and passion of young people-especially when it comes to protecting wildlife. The students at The Little School in Bellevue, Washington are just one example of what a small group of people can accomplish together.

Spencer (3 yrs old) and Luci (9 years) of The Little School in Washington proudly display signs demonstrating their fundraising efforts for amphibians in Panama!
Spencer (3 yrs old) and Luci (9 years) of The Little School in Washington proudly display signs demonstrating their fundraising efforts for amphibians in Panama!

The Little School is a progressive preschool & elementary school for 160 children in Washington state. They first became interested in frogs, and specifically frogs at the El Valle Amphibian Conservation Center in Panama after they visited the Wildlife Conservation Network Expo last year in San Francisco (by the way…the expo is coming up again soon-October 12th from 10am to 6pm if you’d like to attend!). The entire school was presented with numerous projects to raise funds for, and they voted on frogs! From there, it didn’t take much to mobilize and energize these young students to raise awareness and funds for some of the most interesting and important vertebrates on the planet!

In just under a year, the Little School raised $3,000 for frogs in the wild!!!

The students were able to raise this money through various events including a “Hop into Summer Reading” used book sale and a “Frog Friday” Lemonade and Cookie Stand. With  just a bit of guidance from their school leaders, the Houston Zoo and El Valle Amphibian Conservation Center, these students were off and running on their fundraising campaign, and it paid off.

Thank you to the students and faculty of the Little School for your efforts to raise awareness and funds for amphibians in Panama. We can’t wait to see what this energized and passionate group of students does next!

Thank you toThe Little School from the amphibians of Panama!
Thank you to The Little School from the amphibians of Panama!

Is That a Houston Toad Hopping in my Yard?

The Houston area has been very fortunate so far this summer to have had rain. Not only is the rain keeping our outdoor plants and trees alive, it has also increased the activity of many nocturnal critters, especially amphibians!  After a good rain, we get lots of emails here at the zoo from people wondering what sort of frogs and toads they are spotting  around the places they live.  In this post we will discuss the three, most common amphibians that you have seen (or heard) around your house or apartment in Houston!

1) Gulf Coast toad (Incilius nebulifer) – This toad is the most common amphibian found in everyone’s backyards, school play grounds, bayou easements, and parks. These hardy little critters can live almost anywhere as long as there is some access to water. Ever find a toad sitting in your dog’s outdoor water bowl? It is most likely a Gulf Coast toad. Because they have a somewhat similar appearance (thickened, warty skin that is dark brown, tan, and green in appearance) many people mistake Gulf Coast toads for Houston toads; however, Houston toads haven’t been found in Houston for more than 20 years.  To learn more about the differences between a Gulf Coast toad and a Houston toad, please check out this video.

2) Rio Grande Chirping frog (Syrrhophus cystignathoides) – Have you ever been outside at night and heard what you though sounded like a bird chirping in the bushes? What you heard is not a bird at all, but a tiny little frog! The Rio Grande Chirping frog is a little over an inch long and often brown or yellowish green in color. Because they are so small they are often very difficult to spot at night hiding in the bushes, plants pots, or in leaf litter. Though they are originally from northern Mexico and the Rio Grande Valley in Texas, these little frogs are increasing their range due to the transport of pots and plants from these more southern areas!

3) Green Tree Frog  (Hyla cinerea) – The Green Tree Frog can be commonly heard in neighborhoods and parks around Houston that have both trees and water.  Good places to listen for these frogs in the evening are Terry Hershey Park, the arboretum at Memorial Park, as well as Herman Park and the Houston Zoo.  These very green frogs (hence the name) are around 2.5 inches long and have a white stripe down the sides of their body. These frogs sound like a duck when they call at night and many people mistakenly think that they are hearing waterfowl roosting in trees!

To learn more about how to tell the difference between the different toads in our area, please visit the Houston Zoo’s “Know your Toad” page.

Think you’ve heard one of the above amphibians call? Check out the following pages to double-check!

Gulf Coast toad information


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