Saving the tadpoles: when too many tadpoles have not enough food (Part 2)

What do you do when your tadpoles don’t mature? Follow my journey through relocations and searches for just the right food to send my farm tadpoles onto their journey to maturity.

Colorado’s high-elevation semi-arid shortgrass prairie east of the Front Range is home to ranchland dotted with shallow seasonal clay-lined “stock ponds” that hold water for a while after a torrential rain from a thunderstorm. These temporary ponds are known as “vernal pools” or “vernal ponds”, which are located at low spots and filled with rain runoff from the surrounding fields. Some are small, not more than a foot deep, and may more appropriately be called puddles. Others are much larger and may be a couple of feet deep. Regardless of size, these vernal pools provide water for livestock and wildlife, including birds.

Prairie dwellers such as plains spadefoot toads and numerous other species – not only of other toad varieties, but also dragonflies, damsel flies, hover flies, tiger salamanders, and even tiny fresh-water mollusks known as “fingernail clams” – rely on these temporary ponds to hold water long enough for the adults to reproduce, and for their offspring to mature and carry on the legacies of their respective families.

An afternoon thunderstorm at an appropriate time in early- to mid-summer prompts the toads to awaken and emerge from their burrows, gather in the pond of their birth, croak through the night to attract mates, lay their eggs, and disappear again (generally by the following day) to their underground torpor waiting for another appropriately-timed thunderstorm. Ideally, the pond will fill with rainfall from a thunderstorm, and subsequent rains will keep it adequately filled for at least a month while the pollywogs develop.

The ponds are often murky with mud stirred up by tadpoles seeking food at the bottom, at least until the pollywogs mature and move out. (I’m using the terms “pollywog” and “tadpole” interchangeably – both refer to the larval stages of frogs and toads.)

The surrounding vegetation consists of native grasses and forbs, wheatgrass, and sedges.

Normally, it takes about a week for the pollywogs to hatch, and another three to four weeks for them to mature and leave the pond. I’ve run flexible three-quarter inch irrigation pipe to the pond so it can be refreshed with water if rains don’t provide sufficient supply while the tadpoles develop.

In 2021, we had a good rain with a thunderstorm on May 31. A couple species of toads were heard croaking from the pond that night. I saw some of them, but they mostly submerged and all were quiet when I approached the pond. This behavior was different from previous years, in which I had been able to get closer and photograph them, their eyes reflecting the light of the camera or my headlamp, and their voices calling. The photo below is from June 1, 2019.

A week after the end-of-May rain and subsequent toad gathering, tadpoles emerged on schedule. At first, most were very dark, almost black, and tended to cluster along the shallow east edge of the pond. A week or two later there was another thunderstorm, and I thought I heard toads at the pond again. There may have been a second batch of pollywogs.

Weather got hot in June with temperatures in the 90s, and in that shadeless environment, it was over 100 degrees Fahrenheit in the afternoons. Nighttime temperatures at this elevation are very comfortable, at around 60 degrees Fahrenheit. The hot days evaporated much of the water from the pond, and though it became much smaller,  I kept it from drying out.

More than a month after the tadpoles should have matured into toads and left the pond, they were still there; it was mid-July. “Maybe it’s the second batch,” I thought. Early August, they still were there, smooth-bodied and legless. Pollywogs normally eat a lot of algae, and there was no sign of algae in the pond. I thought perhaps they weren’t getting sufficient food to mature. I found some old fish food stored in the garage that I’d had years before for goldfish and koi in a garden pond. Mice had eaten the pond pellets, but the canned flakes were still there, and I began feeding some to the tadpoles. Still, no further development.

Into August, I became concerned that these guys wouldn’t mature and move out of the water before freezing temperatures and snow arrived. (The previous year’s September 8 snowstorm was unusual, but weather had become more erratic in recent years.) I did some research and found that, indeed, lack of food can cause tadpoles to remain as tadpoles. The other problem that was mentioned – colder water temperature – was not likely a problem given the shallow water and very hot daytime temperatures. I determined to double down on the feeding. What I had read said that pollywogs might even remain in the larval stage through to the following summer, if they can survive the winter – which they wouldn’t here, unless taken indoors.

The old fish food was used up, and I had ordered more. I tried to find brands that had more actual food and less wheat flour, corn gluten, and soy meal. I have no idea why fish food includes artificial colors, alcohol sugars, sometimes garlic, and occasionally even rosemary. I wasn’t certain how pollywogs would tolerate such foreign ingredients, and started those foods gradually.

You cannot assume that the item in the product name is even in the first half-dozen ingredients of the ingredients list! You must read the list of ingredients to determine if it’s something you want to feed your fish. 

Even in products that claimed to be “algae wafers”, spirulina or kelp or algae wasn’t listed until the sixth to ninth ingredient – the first five were fish meal, grain meals or flour, and soy meal. Foods designated for herbivorous fish such as algae-eaters, plecostomus, and other bottom-feeders had various kinds of fishmeal as the first and second ingredients, which were followed by wheat and soy meals, and then finally spirulina and other plants. You cannot assume that the item in the product name is even in the first half-dozen ingredients of the ingredients list! You must read the list of ingredients to determine if it’s something you want to feed your fish. I could not find a fish food that was primarily algae. Some foods even appear to be primarily fillers of grains and soy fortified with vitamins.

At first, I used floating KayTee pond pellets and Tetra pond flakes. Right after feeding them, the tadpoles seemed less frantic and more inclined to disperse rather than clump together, but they still didn’t advance in their development.

I decided to move some of the tadpoles out of the stock pond into places near the house: a low stock tank, a tiny pool in the yard, and the old garden pond, which had once provided a home for a brood of tiger salamander larvae to grow up.

Running water into the pond and taking a pail and plastic cup to catch and carry the tadpoles, I was astonished to estimate about 2,000 of them clustered into a single thrashing heap at the point where the fresh water ran into their pond. Catching them was unexpectedly easy. The pond photos below, of this crowding at the inlet, were taken after removing 1,000 or more to a bucket.

Gathered, fed, and ready for transport…

I wound up with a few hundred in a low stock tank, a few hundred in the old garden pond, 100-200 in half of a blue plastic 55-gallon tank, and a dozen in a tiny pool in the yard. The small stock tank had had water in it previously, and its sides were coated in a thin layer of green-looking algae. I dumped out the old water, and left the algae on the sides for the tadpoles to eat (after I refilled it) – which they did in short order. I even relocated some of the algae from the tiny pool to the other tadpole locations, hoping that more algae would grow from it.

In the process of making sure all the tadpoles were out of the bucket (I didn’t want to dump muddy water into the new locations), I found three of the tiny freshwater mollusks that had so baffled me about the same time last year (late summer 2020). I released them into the garden pond. You can read about last year’s discovery here (https://www.theothercolorado.life/2020/09/01/mollusks-on-the-prairie/).

When I went to order more of the same Tetra pond flakes, the price had nearly tripled, so I switched to Aqueon Goldfish Flakes. I also ordered four more 3-pound bags of KayTee floating pellets. (I should have ordered more, because next time I looked, they, too, were more than double the price.)

I did finally find a food that appeared from the ingredients list provided by an online store to be mostly algae, but actual images of the ingredients list of the same product on other sites showed the first ingredients were salmon and herring – still, an improvement over fish meal and grain products. The food was expensive, but time was growing short to get these pollywogs matured. I ordered some to try it. This pricey food was Omega One Veggie Rounds, available in multiple sizes from different sellers. From the varying ingredients lists provided by different sellers of several Omega One products, I suspected that the recipe for some of their fish foods had been tweaked a couple of times. Regardless of the specifics, the basic ingredients were the same, and the results with the tadpoles were soon noticeable.

The day the new Aqueon flakes and Omega One Veggie Rounds arrived, I noticed at the evening feeding at the blue container that a few of the pollywogs were dying, and quite a lot weren’t behaving normally and had cloudy-looking skin. I was concerned that something, perhaps a fungus, had infected them.  Normally, I prefer to introduce one new thing at a time, to make troubleshooting of any subsequent problems simpler, but in this container with so many unwell tadpoles, I broke that rule.

The Aqueon food included garlic (as well as chili powder and marigold powder), and the Veggie Rounds contained vinegar and rosemary, all of which I was concerned might adversely affect tadpoles. But at that point I thought garlic and rosemary might help clear up a fungus, and I fed them some of the new foods. (It also rained that night.) The following day, the tadpoles had improved. By the day after that, they were were zipping around as they normally would. Some of them had grown a bit larger, and many were changing from teardrop-shaped to mouse-shaped. The day after that (August 28, 2021), most seemed to have grown a bit more, and a third or so were beginning to grow hind legs. The tadpoles that I had relocated to the tiny pool, the stock tank, and the garden pond lagged a day or two in development behind those in the little blue tank. Those remaining in the stock pond didn’t seem to change until a few days later.

With its rubber liner torn and partially absent, the garden pond required daily refreshing with water. Maturing toads would be able to exit the tiny pool and the garden pond on their own. I stacked flagstones in the blue plastic container, providing a place for maturing toads to get out of the water, and I added a rock to the low stock tank. As soon as I noticed and could catch them, I would return nearly-developed pollywogs to the stock pond so they wouldn’t be confused about where to return after an early summer thunderstorm.  One such happy event had occurred when one of the tadpoles in the little blue container had grown both functioning hind legs, a right arm, and its left arm could be seen moving beneath the skin. I scooped  up the little fellow, fed it well, and returned it to the stock pond.

In the garden pond beside the house, the morning of August 27, 2021 I noticed some of the plants and even the tall sunflowers had been knocked down or off to the side when something evidently went down the bank and through the water. The cats wouldn’t go splashing through a shallow garden pond. I don’t know if the skunks would. I was betting on the never-seen animal that had sometimes thrown lids off of the trash cans used to store the various bird seeds. The only animals I know of (lacking native monkeys and apes in North America) that are known to remove trash can lids are bears, of which there are none here, and raccoons. I was betting on the raccoon in spite of never having seen one here. The trail through the grass and weeds would have been about raccoon-sized.

At the stock pond on August 27, I had used up a whole 8.1 ounce can of the Veggie Rounds (and could easily have used a second, had there been one), half of a can of Tetra flakes (a different variety from the original), half a can of the Aqueon flakes, and numerous handfuls of KayTee floating pellets. At about a pound and a half of fish food per day, I hoped the tadpoles would soon mature!

Although I hadn’t noticed advancing development in the stock pond tadpoles a couple of days prior, after a few days with reduced population and two days of feeding with the sinking Veggie Rounds and Aqueon flakes in addition to the usual Tetra flakes and KayTee floating pellets, I did see a change. I got quite excited when I noticed one little toad of a lighter almost tan color appearing quite far along with both legs and one, possibly both, arm(s) – though it still stayed completely submerged. The Omega One food may be well worth the higher price.

Feeding the tadpoles at the stock pond the morning of August 29, 2021, I was dismayed to observe that there appeared to be fewer of them. I suspected that a raccoon had made a meal of some of them overnight. Though I’ve seen raccoon-looking handprints in mud at the stock pond (and hind footprints as well, the previous year), I’ve still not actually seen a raccoon here; there’s just the belief that nothing else would have flung off the trash can lids. (In 2020, it managed to pry up a tied-on lid far enough to squeeze inside, tear up a bag of cat food stored in it, and then exit.) I needed to cover the two tanks at night, though there wasn’t much to be done to keep a predator out of the garden pond.

Well into September, I continued to feed tadpoles, keep track of their growth, and return them in a pail-full at a time as they grew legs.

The tadpoles in the photo above are being returned to the pond. There’s a raft of grass stalks and leaves, offering the option to support themselves out of the water so they can breathe.

Some of the features to look for in identifying frogs and toads and their larvae (tadpoles/pollywogs): whether in bright light the pupil is round or vertical; whether the white mouth parts are smooth or serrated; the configuration of the black teeth; whether or not there is a hard lump atop the head between the eyes (some of the spadefoots have them); tadpole shape when viewed from the top; configuration of various anatomy near the base of the tail. Toads’ eyes are more atop the head; frogs’ eyes are set further to the side rather than on top. This last attribute makes me wonder if the tadpole at the top of the photo above (of tadpoles in the pail to be returned to the stock pond) is a frog rather than a toad – look at the difference in location of the eyes. It also has a smooth oval appearance, rather than being angular like the others. It’s more rounded at the mouth end, whereas the others come to more of a point.

Thankfully, there was not a September snowstorm in 2021, and by October, the tadpoles had left the pond. At that point, the water cleared up and the fingernail clams could be seen scooting around. Since the clams had appeared in 2020 and were there again in 2021, I assumed that they must dig into the mud and overwinter. After the pond dried up for the winter, I was sad to see that’s not the case, as the baked mud was covered with hundreds or thousands of little clam shells – so small and blended into the mud that they were hard to recognize and could have gone unnoticed by anyone not looking for them.

No longer devoured by tadpoles as soon as it began to grow, algae was returning to the pond.