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

Tarantulas and scorpions have long been invertebrate pet staples, with over 150 species being captive bred in large numbers.  However, insect keeping, always popular in Japan but much less so elsewhere, is now coming into its own in the USA.  I recently found that over 50 stick and leaf insect, 30 mantid, 25 cockroach and 25 beetle species, along with numerous grasshoppers, katydids, butterflies and moths, are now regularly bred in captivity.

Velvet Ants, Tarantula Wasps, Giant Water Bugs and innumerable others are also kept in smaller numbers, and are growing in popularity.  An aquatic insect exhibit I recently designed for the Brooklyn Children’s Museum, featuring the usually ignored Water Scorpions and Whirligig, diving and water scavenger beetles, is a big hit with visitors.

Grand Possibilities

The potential diversity of insects that may be kept in captivity is limitless, and many exhibit their entire life cycles and full range of behaviors in a relatively limited space and time span.  Those who keep insects are offered the real possibility of discovering new information.

Conservation Value

Much of what has been learned by those keeping insects in private and public collections has conservation value.  Captive breeding and reintroduction programs for endangered species ranging from Sphinx Moths in Arizona to Burying Beetles in Rhode Island have yielded promising results.

Other Invertebrates

An astonishing array of other terrestrial invertebrates are also being kept and bred in captivity, including Banana Slugs, trapdoor, orb-weaver, wolf and crab spiders, centipedes, millipedes, Vinegaroons and Sun Scorpions, to name just a few.  

Further Reading

Japan’s Tama Zoo boasts 2 giant insect houses…be forewarned, insect aficionados who visit will emerge in shock, as did I!

Phasmids (walking sticks and walking leaves) have long been popular as captives in Europe. Photos of many of the nearly 3,000 described species, along with natural history notes, are posted here.

Founded in 1892, and with roots dating to 1872, the NY Entomological Society is an invaluable resource for insect enthusiasts. To learn more about this well-respected group and its publications, please visit their website.