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!

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


Stumpy the Houston Toad

This post was written by Jacquelyne Brauneis


Who is this gorgeous toad in the picture you ask? Why that’s Stumpy, and I’m here to tell you her story. Stumpy is a Houston toad survivor, which is an amazing accomplishment as there are so few left. It is because of this that I decided she needed her story told.

Stumpy’s ancestors hail from a pond in Bastrop state park, and are uniquely grouped together as “strand 4”. Stumpy was born at the Houston Zoo on March 30, 2009 making her 4 years old. Originally, Stumpy was going to be part of assisted reproduction program, which would aim to produce tadpoles from viable female and male toads. But an infection would soon halt any future reproduction efforts on Stumpy’s part.

On November 6, 2012 Stumpy was taken to the zoos veterinary clinic. She was showing signs of swelling in her front right digits, which is a tell tale sign of a mycobacterial infection. Mycobacterium is a genus of bacteria, which is notoriously hard to treat. It usually proves fatal for the toads. Luckily for Stumpy, the infection was in her digits, which could be amputated without taking away her quality of life. If the infection had been any higher, say around her knee area, her future would not have looked so bright.

After an aspiration of her digits came back positive for Mycobacteria, it confirmed what everyone had presumed. Amputation was Stumpy’s only option. On November 10 her 1st, 3rd, and 4th toes were amputated, with the hopes that this would both stop the infection from spreading but also allow her to heal properly. Unfortunately 2 days later, it was obvious that her infection was not improving, so the veterinary team elected to amputate the entire front right foot.

Stumpy healed quickly and enjoyed her hospital stay, which included a private toad suite of her own and daily cricket feedings. With her foot healing, Stumpy was prepared for release and returned to the Houston Toad facility on December 6th.

Stumpy now spends her days, hopping around (or stumping around if you will!), playing in her water, sleeping in her toad house, and enjoying her meals of crickets. While she may be one foot short, she doesn’t let that stop her! She is incredibly fast, and usually beats her 4 legged tank mates when it comes to getting food.

Jacquelyne cleans Stumpy's tank.
Jacquelyne cleans Stumpy’s tank.

Obviously her name came from her “stump” where her foot used to be. Stumpy embraces it, and will come to the tank when I call her (unless she’s comfortably in her toad house, then the only thing that will get her out of there is crickets!). When I call her by name (or one of the many nicknames I have made up for her, such as “Miss Stumps”) she looks up at me with a sweet knowing look in her eye.

That’s the amazing thing about the Houston Toads. They are very cerebral, far more than people will give them credit and they do have unique personalities. Unfortunately their numbers are critically low making it almost impossible for people to see this side of the toads. As an Intern, I feel truly lucky to have met an animal like Stumpy and she has truly inspired me.

Like I said before, she is a Houston Toad survivor. With population numbers so low, the Houston Toad community needs all the survivors it can get. Stumpy is truly a “toadally” amazing toad!

Houston Toad Release: Round 3

We are pleased to announce our third Houston toad release for the year! Last weekend, we delivered 200 juvenile toads (each averaging only between 1 – 2 grams) into an area outside of Bastrop State Park. We have now released three major life stages since March of this year – eggs, juveniles, and adults.

little toad

The toadlets released last week were from the same egg strands that were delivered to areas adjacent to Bastrop State Park in May. One of the zoo’s critical roles in the Houston toad recovery program is the maintenance of a captive assurance colony; therefore we keep back some individuals from each strand produced at the zoo that is destined for release. The captive assurance toads are in essence a “library” for the toads that we release to the wild.  These individuals that we keep will also become our breeders in the future.

We kept ~50 eggs from each of the egg strands released in May, expecting that many would not survive; however, almost all of the eggs we kept made it all the way through metamorphosis, producing too many captive assurance toads for us to keep! (This is certainly not a bad problem to have!) We contacted our collaborators at Texas State University and arranged for these “extra” juvenile toads to be released at the same ponds that the eggs (basically their brothers and sisters) had been previously taken.

little toad 2

Two of our volunteers, Stephanie (intern) and Jacquelyne (volunteer) accompanied graduate student Melissa (Texas State) and me out to the egg release sites.  The day was overcast and the ground was moist from the previous day’s rain, which are perfect conditions for toads! We placed the juvenile toads under deadfall (dead trees lying on the ground) taking special care to ensure that there was no sign of fire ants. The little toads either disappeared under the logs into hiding, or went boldly off into the woods to explore their new home.  It started raining at the last release site (again, great for toads but it made for a soggy ride home back to Houston). Cross your fingers that these summer rains keep on coming!

Melissa will continue to monitor these ponds throughout the rest of this year and next. Hopefully she will see some of our little guys again in the spring!

My, Do Our Babies Grow Up Fast!

It is hard to imagine that only a few weeks ago that the tiny toadlets pictured in these photos were tadpoles swimming in a tank! Our little toads have grown so fast! Though we typically raise our own small invertebrates to feed the juveniles, these little guys have grown so quickly that we will soon have to start ordering a small sized (1/4 inch) crickets!  toadlet-resize

These toadlets are the offspring of our eggs that we released into the wild in and around Bastrop State Park this past spring. We kept some of the eggs back to raise to “toad-hood” as part of our mission to serve as an ark for the species. Additionally, once these little toadlets mature, they will produce offspring of their own for release in the future!

toadlet2resizeWe have been very successful in raising the tadpoles and subsequent toadlets that we kept back from our releases. Of all the tadpoles that hatched from the eggs, we only lost 5! We now actually have too many toadlets (200+) to keep here at the facility! In the coming weeks, we will once again work with researchers from Texas State University and USFWS to release these little guys back out into the wild. This will mark our fourth release of the year and is the first time ever that we have released three different life stages: eggs, juveniles, and adults!

Many thanks to all of our supporters! We couldn’t do this without your concern for the future of this amazing native Texan. Stay tuned for information on our up-coming toadlet release!

Houston, We Have Legs!

In the last blog post, we discussed how egg and tadpole development can be broken down into various stages, called Gosner stages. The stages start with the fertilization of the egg (Gosner stage 1) and extend to Gosner stage 46, which is when the baby toad (also called an emergent) absorbs all of its tadpole tail.

emergent-with-tailLate last week, one of our tadpole tanks reached the developmental stage that we have been carefully monitoring for – Gosner 42! Gosner 42 is a really important time point in metamorphosis in which the tadpole starts to develop lungs. This means that the tadpole will soon give up its aquatic lifestyle for a new life on land.

We know that tadpoles are reaching this critical time point because they start to grow their front limbs. Did you know that both limbs don’t “sprout” at the same time? While we are monitoring for Gosner 42 stage tadpoles, it is not uncommon for us to see tadpoles swimming around with three legs!

Once one front leg is observable on a tadpole, we carefully collect it from the tank with a net and transfer it to a tank with shallow water and moss. This setup allows the tadpole access to both water and land as it finishes transitioning from gills to lungs.

As of today, we have 19 emergents from our first round of breeding several weeks ago. Several of these little guys still have some of their tail remaining, while others look just like tiny toads! Each emergent weighs less than a gram. It is hard to imagine that in a year they will weigh from 20 to 50 grams!


We are currently also caring for 47 tiny little toads that were head-started by our collaborators at Texas State University. These little toads are from egg strands collected around the Bastrop area and are the first wild toads to be brought into the facility since 2010. These toads will hopefully add “new genetics” to our captive colony, which is important so that we can maintain high genetic diversity in the eggs, larva, and toads that we release back into the wild in the coming years.

Stay tuned as we post more updates our newest additions!

Raising a Houston Toad

So what does it take to raise a Houston toad from an egg? A lot of water quality testing, algae paste, and some good ol’ fashioned TLC.

The Houston toad facility at the Houston Zoo has four sets of tadpole racks that are designed to raise eggs to tadpoles. The racks themselves are made up of four aquariums with a circulating water system that runs through a set of filters. Water quality is of upmost importance, and the water is tested for the presence of nitrogen waste products every day.  Additionally, old food and debris are removed on a regular basis. The water in each rack is replaced as needed to keep it as clean as possible.

Unlike the carnivorous adults, Houston toad tadpoles are primarily vegetarians. In the wild they eat a variety of aquatic plant matter, as well as pine pollen that falls on the pond’s surface.  Here at the zoo the tadpoles are fed algae wafers and an algae paste that is smeared on pieces of PVC (which sinks to the bottom where the tadpoles like to feed). Older tadpoles are fed pieces of sweet potato and bok choy for additional vitamins and minerals.

As the tadpoles grow, they start to show distinct physical characteristics that can be used to determine what stage of metamorphosis they are in. The characteristics have been broken down into specific developmental time points called Gosner stages.  For example, when tadpoles start to develop a mouth they are in Gosner stage 23, Gosner stage 26 is when the hind limbs start to form, and Gosner 42 when the front limbs start to form.

We carefully monitor the tadpoles when they get close to Gosner 42. It is at this point that we collect the tadpoles from the tadpole tanks and transfer them into a separate tank with shallow water and moss. Not only are the tadpoles forming their forelimbs at this point, but they are also changing from using gills to lungs; therefore, it is very important that they have a surface that they can use to crawl up and out of the water!

We monitor the little toadlets until they completely absorb their tadpole tail. Did you know that the tail is the little toad’s first meal? Yummy! Once they absorb their tail they are carefully moved to another tank designed with shallow water and lots of moss that they can hop around on. In these tanks the toadlets are fed tiny insects called springtails.  As they grow they are offered larger food items, such as baby crickets (called pinheads), fruit flies, bean beetles, and eventually crickets.

Currently, we have 6 tanks of tadpoles that we are caring for that will eventually make toads that will become members of our captive assurance colony (which means they will be parents in the future!) Our oldest tadpoles are just now growing out their back legs (Gossner 28). We’ll keep you posted on their progress!

A Houston Toad Success Story!

The past three weeks in the Houston toad facility have been a whirlwind of activity. Keepers, veterinary staff, and toads have all been racing the clock to get everything prepared to try to squeeze in a breeding event before the end of Houston toad’s normal breeding season. We are happy to announce that in all we were able to produce ~36,000 Houston toad eggs that have now been released in and around Bastrop State Park.

This marks the first release of eggs from the Houston toad facility. Generally, the survivorship of eggs in the wild is quite low, around 0.01%! However, our collaborators at Texas State University placed the egg strands inside wire cages, termed “predator excluder devices,” to protect the eggs from getting eaten by birds, fish, aquatic invertebrates, and even other amphibians! The eggs will develop and hatch inside the protective wall of these cages. Eventually, the resulting larvae and tadpoles will swim through the wire mesh; however, the cage will be left in the water so the tadpoles can continue to use it as a hiding place.

A graduate researcher from Texas State University is currently monitoring the developing eggs. She has recently observed very large Houston tadpoles hanging around one of the excluder devices from the first batch of eggs released, indicating that they are working and the tadpoles are surviving!

We kept a few of the eggs in the Houston Zoo’s toad facility to grow up to “toadhood” so they can be a part of our captive assurance colony.  These little toads are the offspring of some of our oldest and most “genetically precious” toads that we have here in the facility. Two of the females and three of the males that laid eggs last week are members of the very first group of toads that were brought into the toad program in 2007. We’re so happy that these toads are getting their offspring back into the wild!

Fingers crosses that the egg strands will produce lots of little toadlets that will be chorusing at the Bastrop ponds next year!

Houston Toad Release Success!

Houston toad egg strands

Last week, we transferred 6 total egg strands (~20,000 eggs) to our collaborators at Texas State. We had the opportunity to assist a TSU graduate student in placing the eggs inside protective wire cages in an area outside Bastrop State Park. We were able to check on the eggs transferred the previous week and found very large Houston toad tadpoles, indicating that our first round of released eggs had survived. 

There were also three toadlets that would be the appropriate age to be the offspring of the first set of adult toads that were released from our facility (and subsequently laid eggs) at the same pond back in March.  

In summary this spring we have released:

139 adult Bastrop county toads

631 adult Leon county toads

~36,000 Bastrop county toad eggs

For more on this fabulous program and how you can help the Houston toad click here .

 Check back for more about how the Houston Zoo is helping to save animals in the wild!

Search Blog & Website
[jetpack_subscription_form title="Subscribe to the Blog" subscribe_text="Enter your email address to subscribe and receive new blog posts by email."]
Houston Zoo Facebook Page
Animals In Action

Recent Videos