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

As mentioned in Part I of this article, tiger salamander larvae (Ambystoma tigrinum), run through with a hook while alive, are still used as fishing bait in some parts of the USA.  Last time we learned about the bait trade’s role in spreading a Chitrid fungus that is decimating amphibian populations worldwide, and in hastening the extinction of endangered tiger salamanders through hybridization.

Endangered but Legally Exploited

Despite the aforementioned environmental nightmares, the bait trade in tiger salamanders remains largely unregulated, resulting in infected animals being shipped from state to state.  This practice hastens the spread of already fast-moving pathogens and of non-native salamanders, as surveys have revealed that most people and bait shops release unused larvae into local waterways.

The situation is rendered all the more bizarre by the fact that these largest of all terrestrial salamanders are critically endangered in many areas.  In fact, several subspecies, including the Eastern tiger salamander (Ambystoma tigrinum tigrinum), are protected by individual states as endangered species!

Other Threats

Tiger salamanders also face serious threats from habitat loss, pollution and the introduction of game fish to breeding ponds.  Their use of two distinct habitats – aquatic and terrestrial – renders them especially vulnerable.

Protection, when offered, is often ineffective.  In New York State, for example, 75 feet of land around breeding ponds is closed to development – but research has shown that few if any adults live within that radius!

Tiger Salamanders in Captivity

Tiger salamanders make interesting and unusually responsive captives. Longevities exceed 30 years, but captive reproduction is still somewhat problematical.  They certainly deserve more attention from hobbyists …please write in for further information.

American Bullfrogs

American bullfrogs (Rana/Lithobates catesbeianus) have also recently been implicated in spreading amphibian diseases (New Scientist: May, 2009).  Researchers monitoring food markets in NYC and California discovered that 8% of the frogs being offered for sale carried ranavirus and nearly 70% were infected with Chytrid!

Further Reading

You can learn about the natural history of the eastern tiger salamander, and the steps being taken by the NYS DEC to prevent its extinction, at

http://www.dec.ny.gov/animals/7143.html.

The Organization Amphibian Ark has taken a leading role in Chytrid research.  Read about how this fungus has caused amphibian extinctions, and predictions for the future of the epidemic, at http://www.amphibianark.org/chytrid.htm.

Image referenced from Wikipedia and originally posted by Tigershrike.

Since their arrival in the US in the early 1980’s, White’s treefrogs (Litoria caerulea) have become one of the most popularly kept of all frogs.  Although longevities of 25 years are known, captive breeding remains surprisingly uncommon.  The white-lipped treefrog (Litoria infrafrenata), a large, attractive relative, is also infrequently bred by hobbyists.  Considering how little we know about amphibian reproduction, and the precarious state of many species, I suggest that interested frog-keepers hone their breeding skills on the relatively robust White’s treefrog.

Distinguishing the Sexes

White’s treefrogs reach sexual maturity by age 2.  Mature males are smaller than females, have loose, slightly dark skin about their throats and, when in breeding condition, sport thickened nuptial pads (used to grasp females during amplexus) on their thumbs.  Only the males call.

The Dormancy Period

A cooling off period, preferably in late winter, is critical to breeding success. Cease feeding the frogs 7-10 days prior to the cooling period and place them into an aquarium furnished with a substrate of moist sphagnum moss and cork bark shelters.

Gradually reduce the temperature to 65 F during the night (a basement is ideal) and 68 F during the day (use a small incandescent bulb to raise the temperature) and maintain this schedule for 4 weeks.  Thereafter, hold the temperature at 65 F round-the-clock for an additional 2 weeks.  The terrarium should be kept in the dark throughout this time, and the frogs should not be fed.

Preparing the Frogs for Breeding

After the 6 week “winter”, warm the frogs to 80 F over a 2 week period, and feed them heavily for 3-4 weeks.  Novel prey animals, such as wild-caught or canned insects, should be offered at this time.

Thereafter, move the frogs into an aquarium filled with 4 inches water and provisioned with live floating plants (i.e. water hyacinth, water lettuce, pothos) and basking platforms.  Use an aquarium heater  to warm the water to 82-85F, and add a florescent bulb to encourage plant and algae growth.  I recommend the Reptisun 2.0  bulb, as its UVB output is ideal for amphibians and plants…avoid strong reptile UVB bulbs.

Using a small submersible water pump, create artificial rain by pumping water into a perforated plastic container or PVC tube placed on the terrarium’s screen cover.  Allow the “rain” to fall for 6-8 hours nightly, beginning at dusk.  This step is vital in inducing spawning, and will usually result in reproduction within a week or so.

The Eggs

If all goes well, you will one morning find yourself in possession of thousands of eggs.  It is wise to plan ahead and arrange for friends or nature centers to take some of the eggs, as crowded conditions can cause the loss of the entire clutch.  Remove the adults and install an air pump driven sponge filter that provides mild water circulation.

In contrast to what is commonly recommended for some other frogs, I suggest raising White’s treefrog tadpoles in plant and algae filled aquariums as opposed to bare, sterile containers.  I have even added green pond water to several tanks with good results.

Further Reading

You can read about White’s treefrog breeding in the wild, and hear recordings of the males’ calls, at http://magneticisland.s4space.com.au/L.caerulea.html.

Please see Part I of this article for general information on some of earth’s most toxic amphibians (if not creatures in general) and for additional newt-keeping observations.

Tiny Newt vs. Giant Toad

The familiar red-spotted or Eastern newt (Notopthalmus viridescens) is at its most toxic in the immature eft (land) stage, but the aquatic adults are none-the-less well protected.

Decades ago, the mascot of an animal importer for whom I worked was a huge marine toad (Bufo marinus).  In those days, animals imported from then French Guyana were particularly massive, and this friendly, 4 pound+ specimen was no exception.  Imported animals which did not thrive following their long journey to the USA, ranging from giant Vietnamese centipedes to small rats and finches, all went to filling this amphibian behemoth’s huge appetite.

As a naïve 13 year old animal caretaker, I once tossed a nearly dead, 3-inch- long Eastern newt to the toad.  The newt was swallowed immediately and, right before my eyes, the toad flipped over…dead (along with my budding career!).  Years later, a co-worker reported a similar incident involving a Western painted turtle (Chrysemys picta bellii).

Interesting Means of Toxin Introduction

Several salamanders have quite unique ways of distributing their protective secretions – fire salamanders (Salamandra salamandra), for example, can squirt theirs for some distance.  Perhaps strangest of all, the Spanish ribbed newt (Pleurodeles waltl) actually drives toxin-tipped ribs through the skin of its back when confronted by a predator!

Cautions regarding Pet Newts and Salamanders

Highly toxic newts and salamanders, including all mentioned in this article, are widely available in the pet trade.  Many make interesting and long-lived pets.  However, please treat all newts and salamanders with caution…always wash well after handling them (most need not be handled, and none appreciate it) and, of course, do not trust them around children, mentally challenged persons, or pets.

Further Reading

Please check out my book Newts and Salamanders  for more information on the natural history and captive care of red-spotted newt, ribbed newts, fire salamanders and their relatives.

Image referenced from Wikipedia and originally posted by Peter Galaxy.

Everyone associates the poison or “dart” frogs (Family Dendrobatidae) with skin toxins, but it is to the slow, seemingly benign newts and salamanders that we should really pay heed. In many cases their toxins are far more virulent and, unlike those of the poison frogs, they are produced internally and are not dependent upon diet for their existence (in other words, the toxins do not decline after a time in captivity, as is the case for poison frogs!).

One of Earth’s Most Toxic Creatures
Over 200 compounds, some of which are medically significant, have been isolated from newt and salamander skins. Western North America’s rough-skinned newt (Taricha granulosa) possesses what may very well be the salamander world’s most powerful secretions…a single adult packs enough to kill 25,000 mice. More than one person (usually male, drunk and involved in some sort of “initiation” or dare), has suffered fatal consequences after swallowing a rough-skinned newt.

Skin secretions entering tiny cuts have rendered researcher’s limbs numb for hours, and a scientist who rubbed his eyes after touching a “woodland salamander” (I cannot recall the species, but belonging to the red-backed/slimy salamander group) wandered about blind for nearly 3 days before being rescued.

Toxins vs. Eel
Although the California newt’s (Taricha torosa) toxins pale in comparison to those of its rough-skinned cousin, they are not to be trifled with. I kept a California newt with an American eel for 17 years. The eel, a voracious predator that would as soon latch onto my hand as anything else, never once molested its seemingly defenseless tank-mate.

Next time I’ll relate an encounter I generated as a foolish 13 year old working in a pet store, which clearly illustrates the toxicity of even the most familiar of North American newts.

Further Reading
You can read more about the natural history and toxicity of the rough-skinned newt at http://www.amphibiaweb.org/cgi/amphib_query?where-genus=Taricha&where-species=granulosa&account=amphibiaweb

California Newt Image referenced from Wikipedia Commons and originally posted by Justin Johnsen

Shocking as it may be to anyone with even a passing awareness of conservation issues, tiger salamander larvae (Ambystoma tigrinum) are still widely used as fishing bait throughout much of the USA.  Run through with hooks while alive, the 6-10 inch amphibians are wildly popular with anglers seeking bass, pickerel and other fishes.

Disease and the Bait Trade

Recently (April, 2009), biologists at the National Science Foundation announced that a significant percentage of larvae in the bait trade have tested positive for the deadly Chytrid fungus Batrachochytrium dendrobatidis.  This fungus has decimated amphibian populations on nearly every continent, and is responsible for the extinctions of local populations and, most likely, entire species.

Herpetologists are working feverishly to control its spread, but are as yet unable to understand why the fungus has become such a devastating problem in recent years.  Often, the only hope for amphibians in its path is captivity   – colleagues of mine recently collected an entire population of Panamanian golden frogs, but the long-term outlook is quite dim.

Virulent ranaviruses, which quickly kill many amphibians, have also been identified in larvae sold in bait shops in Arizona, Colorado and New Mexico.

Hybridization

As if the all this were not enough, the release of bait trade salamanders has resulted in the hybridization of critically endangered California tiger salamander populations (released barred tiger salamanders mated with the California subspecies).

Hybridization threatens survival by altering critical components of the genome.  For example, when various subspecies of ibex (mountain goats) were released together in Spain, the resulting hybrids gave birth during the winter, and the population became extinct.

Getting Involved

Partners for Reptile and Amphibian Conservation http://www.parcplace.org/, an organization of professional herpetologists and interested citizens, supports numerous research programs.  Please be in contact to learn more about this issue and their many interesting volunteer opportunities.

Next time I’ll discuss other threats to tiger salamanders, their conservation status, and problems regarding food market bullfrogs.  

Further Reading

Please see my book Newts and Salamanders  for information on the natural history and captive care of tiger salamanders and their relatives.

Image referenced from morguefile.