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

Today’s update, while concerning an animal not suited as a pet (the American Alligator, Alligator mississippiensis) will I’m sure will be of interest to all who keep or study reptiles.  Scientists from the Savannah River Ecology Lab, working with alligators in Louisiana’s Rockefeller Wildlife Refuge, were surprised to find a high degree of mate fidelity in their study population.

Remaining Faithful Despite Choices

Writing in the October, 2009 issue of Molecular Ecology, the researchers explained that 70% of the female alligators they studied over a 10 year period mated with the same male each year.  This is the first time such behavior has been documented in any Crocodilian, and is rendered even more interesting by the fact that the refuge supports a very dense population of alligators, and females freely move through the territories of a great many males.

A Look Back in Time

Crocodilians are the sole surviving reptiles classified as Archosaurs, a group that includes the dinosaurs and which gave rise to the birds (some taxonomists argue that alligators are closely related to birds, and should be removed from the Class Reptilia).  It is hoped that this newly discovered alligator mating behavior will reveal something about the mating strategies of dinosaurs and the ancestors of modern day birds.

Working With Crocodilians

Crocodilians make poor pets, but, as you see from the accompanying photos, they can be exciting to work with in zoos (please be in touch if you’re considering a career in herpetology).

A pair of Cuban crocodiles (Crocodylus rhombifer) under my care at the Bronx Zoo produced young together over a period spanning 40 years (the photo shows some of the “little ones” rushing to a meal) – but, unlike the Louisiana gators, they were housed together, without others of their kind, and so had little choice!

Further Reading

To read about how other research with alligators is granting us a peek at how dinosaurs may have lived, please see this piece.

Male Great Crested Newts undergo an amazing change in appearance during the breeding season.  In Part I of this article I introduced the natural history of this most beautiful newt, and discussed how to bring it into breeding condition.  I’ll cover breeding details and raising the larvae here.

Courtship and Egg Deposition

Breeding male newts tend to fight and, although severe damage is rarely inflicted, less dominant animals may become stressed and cease feeding. Courting males position themselves near females and appear to direct pheromones towards them with their tails. Females thus stimulated follow the males, push against their tails, and eventually pick up the spermatophore that the male has dropped.

Several hundred eggs are laid, each being individually attached to an aquatic plant. Females use their rear legs to bend a plant leaf around each egg – quite an ordeal, and well-worth watching!

Adults may consume eggs and so should be removed from the aquarium after egg-laying has been completed.  If prevented from returning to land after breeding, adult crested newts usually become quite stressed, thrashing about wildly.  Some subspecies, however, can be habituated to a more-or-less permanent aquatic existence.

Raising the Larvae

Crested Newt larvae generally hatch within a month and transform into the terrestrial phase within 3 months, at which point they average 2.4 inches in length.

The larvae can be raised on chopped live blackworms, brine shrimp, daphnia and similar foods; new metamorphs can be offered 10 day old crickets, blackworms, termites and tiny sow bugs.  Sexual maturity occurs in approximately two years, at which time they will re-enter water to breed.

An Even More Flamboyant Relative

A close relative, Triturus vittatus ophryticus develops an incredibly high crest that starts at the nose area and ends at the tail. This species is now showing up in the pet trade, and can be bred in a similar manner to the Crested Newt.

Further Reading

Please see a book I’ve written, Newts and Salamanders, for more on the care and natural history of Crested Newts and their relatives.

You can learn more about the natural history of each newt in the genus Triturus here.

Larval Crested Newt image referenced from wikipedia and originally posted by Piet Spaans

One of the most over-looked aspects of proper turtle care is the provision of a secure place to hide.  It makes sense that a hiding place would seem unnecessary – after all, turtles can simply withdraw into their shells when threatened.  However, it’s not that simple (as usual!).

Shelter Use in Nature and Captivity

Even though their shells are often hard, and offer excellent camouflage – imagine a box turtle on a forest floor or a leopard tortoise among brush – most turtles become quite stressed if denied a secure place to hide.  Even bold, long-term captives prefer a shelter, at least for sleeping.

Particularly retiring species, such as mata mata, bog and Malayan snail-eating turtles, will often fail to thrive if kept in bare surroundings. Hatchlings, even of common snapping turtles and other aggressive species, are consumed by predators ranging from giant water bugs to herons…most are always “on guard” and will refuse to eat unless given ample cover.

Note: at 80+ pounds, the Common Snapper Pictured here is among the heaviest ever recorded. He is on exhibit at The Cold Spring Harbor Fish Hatchery, which houses an extensive collection of native reptiles and amphibians.

Useful Shelters for Terrestrial and Aquatic Turtles

The Zoo Med Turtle Hut, available in 5 sizes, suits nearly all land-dwelling turtles.  R Zilla Rock Dens sink, and so can be used on land or underwater (check that aquatic turtles cannot lodge themselves inside too tightly, and provide larger shelters as they grow).

The Zoo Med Turtle Dock can be set up to serve both as a basking platform and hideaway for aquatic turtles.  When used in shallow water, the sloping side, top of the platform and tank’s wall form a nice underwater cave readily used by young painted, spotted, mud and other turtles.

Next time we’ll take a look at a few species that have special needs, and I’ll add a note about an old turtle of mine that hides within a unique, very old “cave”.  Please write in with your questions and comments. 

Further Reading

For an interesting report on Eastern box turtle natural history, including the use of shelters in the wild, please look here.

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

I’ve been fortunate in having had many adventures with reptiles.  Some took place in the exotic locales I dreamed of visiting as a child, but one of my first was situated in far less promising surroundings – the sewers below the Bronx, in NYC!

The Legend

I grew up hearing tales of huge alligators that supposedly cruised the sewers of NYC, warmed by the steamy air and gorging on rats, roaches and garbage.  In the 1950’s and 60’s, huge numbers of baby Spectacled Caimans (Caiman crocodylus), dubbed “alligators”, were sold to tourists visiting Florida.  In fact, I was presented with just such a creature by my grandfather.  As the story went, the “gators” wound up in sewers after being flushed or dropped there when they became ill or too large for their owners to manage.

My Golden Opportunity

When I was 10 or 11 years old, construction on the street outside my home gave me a long-awaited opportunity…the chance to sneak down into the sewers on an alligator hunt.  I couldn’t imagine a more fortunate set of circumstances, and felt sorry for the many children deprived of such a grand adventure!

Provisioned with a hook, line and pilfered cold cuts, I spent many summer afternoons stalking the mythical beasts below the streets of the Bronx.  I did see “wildlife” – rats, mice and roaches – but I did not catch any alligators (or infectious diseases, thankfully!).

Fortunately, my interests were wide, and with the aid of my books and the (very!) patient, kind-hearted folks at the American Museum of Natural History’s Invertebrate Department, I was able to determine that at least 3 different species of cockroach roamed the area.

The Reality of NYC’s Sewer Gators

Of course, NYC’s sewer system is a less than ideal home for crocodilians of any type – cold winter temperatures, a lack of sunlight and a poor diet would doom the creatures to brief lives, if ever they were there.

I recently expressed that opinion in an interview that was scheduled to air on the TV show “Monster Quest”.  However, I upon watching the episode I found that I had been “deleted” – hopefully because my comments were not “dramatic” enough, and not due to my poor on-air appearance!

Some Real NYC Crocodilians

About 10 years ago, a young Spectacled Caiman did wind up being caught in a filter at a water treatment plant on the Bronx River…perhaps the first solid evidence of a free-living crocodilian in NYC.  The animal had likely been dumped by its owner a short time earlier, but we could not trace its history.

A young alligator, released into a lake in Central Park a few years back, put Manhattan on the map as crocodilian “habitat”.

Working with Crocs

Happily, as time went on I was able to work with 15 or so species of crocodilians in zoos and the wild.  Please see the attached photos – the beast charging me is a marsh crocodile,  Crocodylus palustris, the long-snouted fellow being led into the net is an Indian gharial, Gavialis gangeticus, and the white specimen is an albino American alligator, Alligator mississippiensis.