That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

The tadpoles of American Toads (Bufo/Anaxyrus americanus) and Fowler’s Toads (B. woodhousei fowleri), and of related US natives, are frequently collected by herpers young and old and taken home to raise.  They usually prove quite hardy, and, even on nutrient-poor diets (i.e. lettuce), transform into tiny toadlets within a few weeks.

Toad Maladies

Young toads often prove difficult to raise however, and each year I receive questions concerning the same 2 problems – bloating and paralysis (difficulty hopping, problems catching food, etc.).  I’ve run across this myself when raising American toad tadpoles for a release program in NYC, where most of the tadpoles transformed, but died soon after.

Nutritional Deficiencies

I’ve come to believe that 2 distinct problems are at work.  Difficulty in using the rear legs is probably linked to deficiency in calcium or another nutrient, but efforts to reverse it, at least in small toads, have proven unsuccessful.
Using supplements on the food given newly transformed toads helps, but we really do not know what most species, especially North American natives, actually require.
Tadpole nutrition is another area that needs investigation.  Poorly nourished tadpoles may transform, but then die several weeks later…I’ve had this happen on a number of occasions over the years, with several species, even the relatively indestructible African clawed frog (Xenopus laevis).

Bacterial Infection

Bloating is usually a byproduct of a bacterial infection, and may be connected to nutrition.  Toads already weakened by a nutritional deficiency may be more likely to become infected with bacteria that healthier clutch mates fight off – hence both symptoms in 1 toad.  This is based mainly on anecdotal evidence, but does seem to happen time and time again, and with several species.

Natural Mortality

Another point to bear in mind is that, among species that lay huge clutches, a great many tadpoles will not survive even under the best of circumstances.  Some turtles lay infertile eggs, apparently to satiate predators and take attention away from viable ones – I have no hard evidence, but I would not be surprised to learn that weaker tadpoles serve a similar function.

Feeding Tadpoles and Young Toads

Most native toad tadpoles are omnivorous.  Try to provide them with as much variety as possible, and bear in mind that, in large groups, smaller, weaker individuals are easily out-competed at feeding time.  I’ve had good luck raising tadpoles on a diet comprised of tropical fish food flakes, algae tablets and kale pre-soaked in hot water (this breaks down thick cell walls). Metamorphs (newly transformed toads) consume scores of species of leaf litter invertebrates in the wild, complicating our job in raising them.  In addition to tiny frog standards such as fruit flies, springtails and pinhead crickets, you might try collecting tiny invertebrates as toad food (please see article below).

Further Reading

Please see my article Leaf Litter Invertebrates for information on collecting live food for tiny amphibian pets.

 Haswell’s Frog tadpole image referenced from wikipedia and originally posted by LiquidGhoul

Few amphibians exhibit a more dramatic change in appearance than male Crested Newts in breeding condition.  It really is something to see and, fortunately, breeding this species is actually quite feasible.  Breeding the crested newt in captivity also has great conservation value, as this species is in decline throughout Europe.  Furthermore, any information garnered is applicable to other species of concern, including the Alpine Newt, Triturus alpestris and the Swiss Newt, T. helveticus.

Natural History

The Crested Newt, which may reach 6.4 inches in length, is grayish to black above and orange with round black spots below.   

Living a largely terrestrial existence for most of the year, both sexes enter breeding ponds in late winter or early spring.  At this point, the males’ colors intensify and a large, comb-like dorsal crest develops. In both sexes the tail also becomes more paddle-like to facilitate swimming. Males also usually develop a white line along the sides of the tail, while reproductively active females sport a white line down the back.

Bringing Newts into Breeding Condition

While breeding may occur spontaneously in captivity, the most consistent results will be obtained if the newts are over-wintered at 36-42 F.  An increase in water depth may stimulate breeding outside of the normal cycle, but fewer viable eggs will be produced).

Upon emergence from hibernation, the newts should be housed in aquarium, or their terrestrial terrarium should be modified to provide a large water area. Resting sites such as cork bark slabs or basking platforms should be provided.

Due to their unique egg-laying behavior (females fold a plant leaf around each egg), crested newts slated for breeding are best housed in well-lit aquariums stocked with live plants.  The water should, if possible, be maintained at 54-65 F (a cool basement or garage often proves ideal).

We’ll take a look at raising the larvae next week. 

Please see Part I of this article to learn about the natural history of the Panamanian Golden Frog , Atelopus zeteki, including it’s unique mode of communication.

Status of Wild Populations

Panamanian Golden Frog numbers are plummeting, most likely due to an epidemic of the largely incurable fungal infection

Chitridiomycosis. The fungus responsible, Batrachochytrium dendrobatidis, has been implicated in the declines and extinctions of numerous amphibian species worldwide. This frog is also threatened by deforestation, stream siltation, pollution and collection for use as a promotional tool in Panama’s restaurant, hotel and tourism industries (this practice is illegal, but enforcement is often lax).

It is estimated that Golden Frog populations have declined by 80% in both numbers and extent of occurrence over a 10 year period. At least 2 distinct populations are extinct, with 1 such extinction occurring within the span of several months. Golden Frogs are designated as “Critically Endangered” by the IUCN and listed on Appendix I of CITES. They are legally protected by Panama and the subject of a cooperative rescue program, administered by the USA and the Republic of Panama, known as “Project Golden Frog”. Fortunately, the Golden Frog breeds well in captivity.

Unique Skin Toxins

This frog’s skin contains extremely virulent nerve toxins that differ from those produced by other amphibians. Known as “zetekitoxins”, the poison contained in the skin of a single 2-inch-long frog is sufficient to kill 1,200 mice! It is believed that these toxins are produced in association with symbiotic bacteria, but this has not yet been definitively documented.

Cultural Significance

The Panamanian Golden Frog is the national animal of the Republic of Panama, and has traditionally been associated with matters relating to good fortune. Pre-Columbian indigenous people molded its likeness in gold and clay talismans known as “huaces”.

Further Reading

You can learn more about Project Golden Frog by clicking here.

Please see Part I of this article for a general discussion regarding the collection of insects and other invertebrates and their use in the diets of captive reptiles, amphibians, birds, invertebrates and fishes. Today I’d like to focus on some areas of special concern.

Toxic and Biting/Stinging Invertebrates

While not involving pesticides per se, for your own safety and that of your collection it is imperative that you learn to identify the toxic or otherwise dangerous invertebrates that you may encounter while collecting. A good field guide (i.e. Audubon, Golden Guide or Peterson series) is indispensable in this regard. Be sure to handle unfamiliar species with plastic tongs.

Please bear in mind that even relatively mild bee venom can cause fatalities in allergic people. And while less than 1% of the world’s 40,000+ species of spiders are considered dangerously venomous to us, a number readily bite both people and animals in self defense. It is best, therefore, to avoid them…the Thin-legged Harvestman or “daddy long-legs”, which are not spiders, are safe to use. Steer clear also of bees, wasps, large ants, stag beetles and others well-equipped to defend themselves.

Bright colors often indicate that an animal is toxic or bad-tasting; ladybugs, fireflies, milkweed bugs and a great many others fall into this category. Unless you are sure of an insect’s identity, the safest course of action is to avoid brightly-colored species.

Native vs. Non-Native Prey Species

In many cases, predators avoid dangerous prey animals that occur naturally within their ranges; this can spare both pet and pet-keeper a good deal of grief!  However, dangerous non-native prey animals may be attacked with abandon if the hunter has no “frame of reference”, so use extra caution in such cases.

I have, for example, housed highly-toxic Marine Toads with Green Anacondas for decades without incident, despite the fact that anacondas consume non-toxic frogs readily. However, Australian monitors and snakes, which have no instinctive or learned toad avoidance behavior, eagerly consume the Marine Toads that have been introduced there, often with fatal results.

Earthworms

Earthworms are one of the most nutritious live foods available. There are, however, situations that warrant precautions.

Earthworms are unique in consuming dirt as they tunnel, and in doing so may concentrate toxins present there. To my knowledge, the only problem that has arisen thus far has involved worms that dwell along golf courses, which are subjected to unusually high degrees of pesticide application. Please see my article Raising Earthworms for details concerning striped skunks and earthworms in NY.

West Nile Control and Related Programs

Avoid collecting invertebrates for 1 week after an area has been sprayed as part of West Nile eradication efforts, and steer clear of farms where pesticides are known to be applied regularly. Avoid also local insects that are considered to be agricultural pests, as they are likely the subject of control measures (this may apply to aphids, caterpillars, Japanese Beetles, etc.).

Enjoy

Despite the precautions that must be taken, invertebrate collecting is a fascinating and thoroughly enjoyable endeavor. Don’t forget to examine your catch closely…several years ago a new species of centipede was uncovered in NYC’s Central Park, on ground trod daily by thousands of people. Like me, you just may wind up keeping some of your discoveries in captivity for their own sake!

Further Reading

For a very interesting account of how toads learn to avoid stinging insects, please see my article Amphibian Learning Abilities.

Please write in with your questions and comments.

Black Widow image referenced from wikipedia and originally posted by Trachemys.

Milkweed Bugs image referenced from wikipedia and originally posted by Greg5030.

In the late 1980’s I was privileged to breed the now rarely-seen Smoky Jungle Frog, Leptodactylus pentadactylus, a large (8 inch snout-vent length) Latin American native that constructs foam nests on land.  In the wild, rain washes the tadpoles into a nearby pool, where they develop in normal frog fashion…following suit, I successfully reared a number in water.  I subsequently learned that some frog nests are placed far from the water’s edge, and that the tadpoles therein develop entirely on land.  But what did they eat…the nest’s foam, perhaps?  There were theories, but no answers.

Subterranean Frog Nests

Herpetologists working with the closely related Mountain Chicken Frog (L. fallax) at the Durrell Wildlife Conservation Trust have recently solved the riddle – and captured the bizarre event on film.  Mountain Chicken Frogs, highly endangered and limited to Dominica, St. Kits, Martinique and a few neighboring islands, lay their eggs in foam nests underground, and the tadpoles develop without ever seeing water.

The startling footage taken by the researchers, shows scores of tadpoles gorging on unfertilized eggs produced by their mother.  In sharp contrast to certain more “civilized” oophagus (egg-eating) poison frog tadpoles, the chicken frog larvae do not wait until the eggs are actually deposited, but rather swarm about the female’s cloaca, eating ravenously as the eggs emerge.  It’s quite a scene!

A Taxing Time for Mom

Subsequent research has revealed that the harried mother uses her rear legs in an attempt to re-distribute the unusual food, and perhaps to give all of her gluttonous progeny a chance to feed.  She has her work cut out for her…the 25 to 50 tadpoles that she rears require 10,000 to 25,000 unfertilized eggs to see them through to metamorphosis!

Further Reading

Frogs break all the rules when it comes to reproductive behavior, constantly surprising even the most seasoned herpetologists.  To read about tadpoles that “petition” their mother for food, please see my article Begging Behavior Among Strawberry Poison Frog Tadpoles.

Smoky Jungle Frog image referenced from wikipedia and originally posted by Ltshears
Leptodactylus fallax image referenced from wikipedia and originally posted by TimVickers