NatureWatch: Amphibian Fun
Toads and Frogs
October 13, 2024
Betsy Cross, consultation with Lee Ann Linam
On occasion, the Leopard Frogs and Gulf Coast Toads in my yard may be seen together, perched on a log, as in the photo above, or sharing space in a watering tub.
Over the last couple of years, these two resident anurans have provided lots of “NatureWatch” opportunities in my yard and plenty of just plain old fifth-grade science fun. Starting with the Gulf Coast Toads, here are a few of those moments.
Gulf Coast Toads - Fall 2023
Gulf Coast Toads (Incilius valliceps)
All photos and videos courtesy Betsy Cross
After a much-needed quarter-inch rain in mid-August during the drought of 2023, the Gulf Coast Toads in my yard emerged from their burrows. The next evening, two toads appeared together in one of my bird watering tubs. Later that night, I heard an uncommon, but not unfamiliar, chorus of toads calling.
Within days, I noticed what I first thought was a swirling mass of algae in the watering tub. But on closer inspection, I realized this was no algae: it was a floating greenish foam, studded with what looked like white millet seed—eggs?
August 26
August 26
I don’t have a permanent water feature, and this was the first time I’d seen any toad breeding behavior in my yard. But rainfall from March through September can trigger reproduction, prompting male toads to gather around ponds, roadside ditches, and other still-water habitats to call out in short, trilled songs.
Females respond, laying long strings of eggs—sometimes up to 20,000—that in this case, transformed a wildlife watering tub into a tadpole nursery. When first laid, egg strands look like a string of black pearls, but after a couple of days, the color and appearance of the eggs shift, as in the photos from August 26 above.
This photo shows a second “string of pearls,” freshly deposited in one of my other watering tubs on the morning of September 12.
To keep the dogs and birds from disturbing the toadspawn, I carefully transferred the foamy mat to another tub and covered it with garden mesh for protection. The next morning, it was alive with tiny white specks, smaller than grains of rice, twitching in the water. By 10 a.m. tadpoles were emerging en masse.
By 3 p.m. the tiny tadpoles had begun to swim and congregate along the ridges of the tub bottom. And by evening, the egg mass had begun to dissipate.
The next morning, tadpoles clustered around the edges of the tub. And by nightfall, thousands of them were swimming everywhere, seemingly doubling in size in just a few hours.
The transformation was breathtaking. Within a single day, the mysterious “algae” had vanished and was replaced by a vibrant swarm of new life.
“Toads jump in and make it happen fast!” —Lee Ann Linam
Gulf Coast Toad tadpoles are adapted for ephemeral wetland habitats—a wetland that forms temporarily in response to rainfall and then dries out periodically. Toad tadpoles emerge from their eggs 1-2 days after deposition and take approximately 20-30 days to metamorphose.
They begin life by consuming the remains of the egg casing and yolk sac, which provide essential nutrients in their earliest days. Once free-swimming, they graze on algae, biofilm, and decaying leaves in the shallow wetlands where they emerge.
In my tub at home, they readily adapted to other food sources, consuming algae wafers and blanched spinach leaves, as seen in this video.
Over the next few days, the tadpoles grew rapidly, eating and exploring every inch of their small world. By August 30, just four days in, they had already quadrupled in size. With thousands crowding the original tub, I realized they needed more space to thrive. Soon, three tubs and a galvanized bucket were pressed into service, and then on September 9, I created an above-ground pond for them in a 50-gallon stock tank.
My online resources advised adding protein to the diet of the growing tadpoles. So I fed them rolls of thinly shaved turkey breast, which I dropped into their tub on a cord so leftovers could be removed easily. It wasn’t long before the tadpoles consumed all the turkey breast in a single feeding (September 13).
They even congregated around my hand when I placed it in the water and gently nibbled away.
By September 17, most of the tadpoles had sprouted legs.
And a few climbed out onto floating leaves and various ramps I’d placed in their pond (September 18).
The setup felt like the perfect nursery—ample space, clean water, and natural features to support their transition to land. For several weeks, the pond was alive with activity. The surface rippled with hundreds of tadpoles and metamorphs.
In the beginning, I utilized a stiff hardware cloth to cover the pond so predators couldn’t get in and feast on the captive tadpoles. But as they metamorphosed into toadlets and started to launch onto the sides of the tub, I removed the hardware cloth cover so they could leave their pond.
September 19
September 20
Soon nature reminded me that my tadpole nursery was also part of a larger food chain. On October 2, I noticed the first sign: a shed snake skin draped across one of the log ramps. The visitor had clearly been there before me.
October 2 - Evidence that a snake had found the tadpole pond.
Just three nights later, I went out with a flashlight to check on the pond. There it was, a Checkered Garter Snake moving through the water like a miniature sea serpent, diving and surfacing, pausing now and then to seize its prey. What had been a nursery for thousands was a hunting ground.
October 5
October 5
With the snake now a regular visitor, the pond no longer felt safe for the tadpoles, and I knew it was time for a change. On the morning of October 8, I carefully collected them all. The majority I carried down to a natural pond, where they could disperse into a true wild habitat. Returning them to the world where they belonged felt like the right next step.
Still, I held back about a hundred tadpoles and moved them into a small aquarium in my bathroom. Over the next few days, I watched the metamorphs leave the shallow water—tiny, alert, and ready for land. As more transformed, I carried them outdoors and released them into the moist leaf litter beneath my trees. One by one, they disappeared under the leaves. I released toadlets all the way through mid-January. Perhaps the wide span of time for metamorphosis, from mid-September through mid-January, was due to inconsistent temperatures at that time of year, predator stress, and food availability.
On October 8, I moved the tadpoles.
October 22
October 26
November 15
The cycle had come full circle.
What began as a surprise mass of eggs in a bird watering tub had become a “stuff in my backyard” moment, complete with predators and rescues, thousands of tadpoles, and the fun of watching tiny toads find their way into the wider world. The following spring, I spotted several quarter-sized juvenile toads in the yard, a stage I had never seen before, and I hoped they belonged to this especially persistent family of Gulf Coast Toads. Sexual maturity for juveniles is reached at one year. The lifespan of Gulf Coast Toads in the wild is 3-5 years.
October 26
See more about Gulf Coast Toads and toad reproduction in Totally Toads, an article with wildlife biologist Lee Ann Linam in the August 2022 Hays Humm, and also Patty Duhon’s article, Toad-a-Palooza, in the September 2022 Hays Humm.
Leopard Frogs - Fall 2024
Leopard Frog
All photos and videos courtesy Betsy Cross
Like the Gulf Coast Toads, the Leopard Frogs have been regular residents in my yard for years. I’ve found them hanging out in watering tubs, sometimes two at a time, and seen them leap from garden beds when startled. Occasionally, I see one on my doorstep in the middle of the night. Individuals appear in a variety of colors, some in shades of green and others in brown and gray, all displaying their traditional leopard-like markings. They are always on guard and quick to leap away when I get too close.
Rio Grande Leopard Frogs or Southern Leopard Frogs?
My property in San Marcos lies along the boundary between the ranges of two species, the Rio Grande Leopard Frog (Lithobates berlandieri) and the Southern Leopard Frog (Lithobates sphenocephalus). These two species are similar in appearance, and telling them apart can be difficult.
Lee Ann Linam recommended a helpful guide for distinguishing between the two species in the blog post Central Texas Leopard Frogs, which is illustrated with photos, drawings, audio recordings of their mating calls, and a map of documented observations.
Lee Ann said that one of the easiest distinguishing characteristics between the Rio Grande and Southern Leopard Frog is their call. Based on my review of the blog post audio recordings and her review of my photos, she and I lean toward identifying the ones in my yard as Rio Grande Leopard Frogs, but we remain open to the possibility of an overlap of the two species.
A Frogspawn Event
I discovered the first Leopard Frog egg mass in one of my bird watering tubs on September 21, 2024. The typical egg mass of a Leopard Frog contains 500-1,000 eggs, far fewer than the toad’s 20,000.
The fist-sized frogspawn, looked very different from the Gulf Coast Toad’s “string of pearls.” These differences can be seen in the two photos below:
Leopard Frog egg mass (September 21, 2024)
Gulf Coast Toad “string of pearls” (September 12, 2023)
Leopard Frog tadpoles typically take 2-3 weeks to emerge from the egg mass—much longer than toad tadpoles, which emerge in 1-2 days. Since the tadpoles of the September 21 frogspawn emerged the next day, it’s likely the eggs had been incubating in the watering tub for two or three weeks before I noticed them.
Leopard Frog tadpoles emerged from the egg mass on September 22 (photo taken at 8:15 p.m.)
September 23, 7:45 p.m. - The tiny tadpoles gathered along the edges of the tub.
Leopard Frog metamorphosis can stretch over three months or longer, and the tadpoles can even overwinter.
Compared to the Gulf Coast Toad tadpoles in the Fall of 2023, the Leopard Frog tadpoles’ growth and development was much slower. The cryptic tadpoles* of the Leopard Frog are adapted for more permanent water sources, where they have sufficient time to complete their longer metamorphosis (though they can be attracted to some “non-traditional” water sources, such as swimming pools, and in this case, my bird watering tubs).
The frog tadpoles also seemed “wilder” than the toads and didn’t feed as actively. Lee Ann attributed the wilder nature of the Leopard Frog tadpoles to their inherent response in permanent water sources, where they encounter the constant threat of fish, dragonfly larvae, snakes, and other carnivorous predators.
*Cryptic tadpoles refer to those that remain hidden among vegetation, leaf litter, or along the substrate.
October 23 - The tadpoles were growing slowly, but still seemed healthy.
November 16 - An adult visits the tadpole tub.
By mid-November, I was concerned that the two month old tadpoles were not getting adequate nutrition. I tried some of the same foods that the toad tadpoles devoured, but the frog tadpoles did not seem interested. I ordered additional tadpole food online, but nothing seemed to entice them to eat in my presence. So just before Thanksgiving, I felt the best chance for the tadpoles to succeed was to release them into their natural habitat. I relocated all but about a hundred tadpoles to a natural pond and placed the remaining few in a tub in my garage so I could continue my observations.
November 24 - I moved about a hundred tadpoles into this tub in my garage and relocated the rest of them to a natural pond.
I had hoped to see them through their metamorphosis, but right after Christmas, I decided to take the remaining few down to the natural pond.
I was a bit disappointed that I wasn’t able to see the Leopard Frog metamorphs. I hope some of them found their way to becoming juveniles. Leopard Frogs reach sexual maturity at 2-3 years. Their lifespan in the wild is 5-8 years.
Perhaps another day may come when I can see a baby Leopard Frog.
On October 11, a second frogspawn, somewhat smaller than the first, appeared in another watering tub.
October 17 - This video is a close-up of the second frogspawn as the tadpoles emerged from their egg mass.
October 8 - The adult Leopard Frogs often visited the watering tubs.
October 19 - Three Gulf Coast Toads share the tub with new Leopard Frog tadpoles.
These two species of anurans, Gulf Coast Toads and Leopard Frogs, exist simultaneously and cooperatively in my yard. During extreme times of drought, they will use temporary water sources to breed and produce offspring. Even if the ecosystem is not natural or ideal, they are compelled to try. The experience of observing and participating in furthering their reproductive process has been interesting and inspiring. My hope is to create an ecosystem in my yard that can support both species in a more natural way.
Lee Ann Linam, Texas Parks and Wildlife Department Biologist and Amphibian Specialist (retired), consulted on this article.