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

 

Please see Part I of this article for a discussion of this turtle’s natural history.

General

As mentioned in Part I of this article, I expect sideneck turtles of various species to become more common in the pet trade in the future.  The information provided here is largely applicable to all 6 species in the genus Podocnemis, but please write in for further details concerning turtles other than the yellow-spotted sideneck.

Please bear in mind that yellow-spotted sidenecks grow quite large, and are best kept by those with the space for a very large aquarium or outdoor pond.  If it becomes available at some point, the smaller red-headed Amazon sideneck, P. erythrocephala, would be more easily managed in the home.

Enclosure and Physical Environment

This turtle spends most of it’s time in the water, leaving only to bask or lay eggs.  An adult male or smaller female (some females top out at 12 inches, while others attain 18 inches in length) will require an aquarium of at least 100 gallons in capacity, but a larger enclosure would be preferable.  Turtles kept in aquariums should be afforded the opportunity to swim and forage in larger, temporary quarters, such as a child’s wading pool, when possible.  Large females will require a custom aquarium or outdoor pond.

A sturdy, dry basking platform must be provided.  Adult sidenecks are quite vigorous, so you may need to attach a piece of driftwood or cork bark to the tank’s side with aquarium silicone in order to hold the platform in place.  This will leave the area below the platform free for swimming – rock piles take up too much space, and can be rough on turtle plastrons.

Hatchlings and juveniles can be raised in smaller aquariums, with Zoo Med Turtle Docks or R-Zilla Basking Platforms used as land areas.

Filtration

Filtration is best accomplished with a strong canister filter, as internal filters will be moved about or broken by these active turtles.  Be sure to choose the most powerful model suitable for the particular enclosure that you maintain.

In common with most aquatic turtles, sidenecks are messy feeders.  They should be offered meals outside of their aquarium, in a plastic storage bin that can easily be dumped and cleaned.  Doing so will go a long way in maintaining water quality and clarity, and will extend the time between filter medium changes.

Light and Heat

Yellow-spotted sidenecks are heliothermic (sun-basking) reptiles and require a source of UVB light in order to produce Vitamin D3 (which is required for calcium metabolism).  The Zoo Med Power Sun UV Mercury Vapor Bulb provides UVB and will help maintain a basking site temperature of 90-95 F.  For smaller aquariums housing young turtles, the Zoo Med Reptisun 10.0 High Output UVB bulb will likely be preferable, as the mercury vapor model is designed for larger enclosures.  Be sure to add an incandescent spotlight for warmth as well.

Yellow spotted sideneck turtles bask frequently in the wild, and require prolonged exposure to UVB in captivity.  If your turtles are nervous and drop into the water when disturbed, consider housing them in a quiet location until they adjust, lest their basking time be compromised.

Water temperature should be kept at 76-80 F.  You may need to protect your submersible heater from the turtles’ attentions with a piece of PVC pipe into which holes have been drilled.

The day/night cycle should be maintained at 12 hours daylight, 12 hours darkness.  If the room’s air temperature falls at night, use an R-Zilla Infra-red Ceramic Heat Emitter ….leaving the basking light on all night will disrupt the turtle’s normal activity patterns, and should be avoided.

Feeding

Young sidenecks of all species lean towards an animal-based diet, becoming more herbivorous as they mature.  Offer as wide a variety of foods as is possible.

Zoo Med Aquatic Turtle Food is specifically formulated for sidenecks and turtles with similar nutritional requirements, and can be the base of the diet for both growing and adult animals.  It is low in protein, which is an important consideration for older sideneck turtles.  When fed to growing animals, this food should be alternated with Tetra Repto-Min Food Sticks and Suprema Food Sticks.

Hatchlings and young turtles should also be offered regular feedings of whole animals, including earthworms, fish, mealworms and their pupae, waxworms, butterworms, crickets, crayfish and small snails.  Canned grasshoppers, snails, shrimp and caterpillars are now available, and, along with freeze dried prawn, should be used to increase dietary variety.

Be sure to include plant material (see below) in the diet of growing sidenecks…animals refusing to switch to a vegetable-based diet as they mature is commonly encountered problem.  Acclimating turtles to all foods while young will help to avoid this situation.

Adults do best on a wide variety of vegetables, including kale, romaine, endive, dandelion, bok choy, cucumber, mustard greens, collard greens, yams and carrots.  Fruits should be offered sparingly, although apples are fine on a regular basis.  The composition of their diet should be varied with seasonally available greens.  Spinach, which binds calcium, should be avoided.

Provide your turtles with the tough stems of kale and bok choy, as these will help to keep the cutting edges of the jaws trimmed.

Captive Longevity

Captive longevity exceeds 20 years.  Please see Part I of this article for notes on a long-lived group of giant sideneck turtles (P. expansa).

Miscellaneous

Sidenecks are ideally suited for outdoor ponds.  Please see A Survey of Amphibians, Reptiles and Insects Suitable for Maintenance in Outdoor Ponds – Part II, the Red-Eared Slider, Chrysemys scripta elegans for general considerations.

 

You can read about current Turtle Conservation Funds projects focusing on sideneck and other turtles at:

http://www.turtleconservationfund.org/previously-funded-grant-awards/

Image referenced from Wikipedia.

Click: The Yellow-Spotted Sideneck Turtle , Podocnemis unifilis, in the Wild and Captivity: Natural History – Part 1, to read the first part of this article.

Diet

Adults are mainly herbivorous and subsist largely upon aquatic vegetation and fallen fruits, but will also consume insects, fish, carrion, snails and crayfish (the preferred diet of juveniles).

The yellow-spotted sideneck sometimes utilizes a feeding method known as neustophagia to filter particulate food matter from the water’s surface.  The turtle opens its jaws at the surface and rapidly pumps the throat, which has the effect of drawing in only the thin surface film.  A rapid snap of the jaw expels the ingested water and retains the organic matter.  Neustophagia enables a relatively large turtle to obtain significant nutrition from a food source that would be otherwise too small to exploit.

This and related turtles sometimes gather in large numbers below trees overhanging water when fruits ripen and fall (please see below).

Reproduction

The mating season varies throughout the range.  As in many aquatic turtles, males court females by stroking their heads with the claws of the forelegs.

Females often nest communally, digging nest holes in sand or, on occasion, in mats of floating vegetation.  Several clutches may be produced each season, with 6-52 (average 19) eggs being laid at once.  The hatchlings average 1.6 inches in length, and emerge after 60-75 days.

Encounters in the Field

While engaged in field work with green anacondas, I was fortunate to find myself in the Venezuelan llanos… prime habitat of the savanna sideneck turtle, Podocnemis vogli, a close relative of the yellow-spotted sideneck.  On one memorable occasion, I came upon thousands of these shy yet inquisitive turtles at a river oxbow, below a stand of fruit trees.

Droves appeared at the surface, briefly looked at the boat and dove, to be replaced by an equal number of turtles a few seconds later.  Upon entering the water, I was astonished to find that the entire pool was packed, top to bottom, with turtles…to move, I literally had to push my way through a nearly solid mass of shells.  Being in the center of so many frantically swimming turtles was quite unlike anything I had experienced, either before or since.

Notes on Related Turtles

Podocnemis erythrocephala

The red-headed sideneck turtle, P. erythrocephala, is a much sought after species that rarely if ever enters the pet trade anymore.  Unlike many turtles, males retain the brilliant red head markings that characterize hatchlings.  Limited to the Rio Negro and Rio Casiquiare drainages in Venezuela and Brazil, it is a secretive species that mainly keeps to blackwater areas.

This turtle’s wild status has not been well-studied, but it is assumed threatened by past over-collection and habitat loss.  Those I have worked with proved to be fairly shy, even after nearly 3 decades in captivity. They did not rush towards me at feeding time, as would almost any other turtle after such a time period, and reproduced only sporadically.  We certainly need to learn more about the keys to the captive breeding of this species.

Podocnemis expansa

The giant South American river turtle (P. expansa) is the heavyweight of the family and, at 3 feet in length, one of the world’s largest freshwater turtles.  Inhabiting tributaries of the upper Amazon and rivers in the Caribbean drainages of Guyana and Venezuela, it favors deep water.  Females have the unfortunate habit of gathering in huge numbers along favored nesting sites at predictable times each year.  This renders both they and their eggs quite easy to collect, and the species is now in dire trouble throughout much of its range.

During my years at the Bronx Zoo, I cared for a breeding group of these impressive turtles, some of which approached 40 years as captives, and were likely 60-70 years old.  Several times I was called to Kennedy Airport to identify turtle eggs found in luggage (and, in one case, filling 2 shopping bags!).  Twice I was tempted to identify seized eggs as belonging to a sea turtle, but upon close examination and some research into the collection site found them rather to be eggs of this massive species.

A great deal of information concerning the harvesting and conservation of this and other South American turtles and tortoises is posted at:

http://www.fao.org/docrep/T0750E/t0750e09.htm

Image referenced from Wikipedia.

The Yellow-Spotted Sideneck Turtle (Terecay, Yellow-Spotted Amazon River Turtle), Podocnemis unifilis, and several relatives were popular pets in the 1970’s, but soon became unavailable due to over-collection (largely for the food trade) and the resulting limitations on importations.  Australian sidenecks soon filled the void, and remain in the spotlight today.

However, captive breeding efforts are beginning to show some promise, and the yellow-spotted and other South American species are poised, it seems, to re-enter the per trade.  These sizable turtles are not for everyone, but we need to learn more about them…hobbyists with some experience and space might help greatly in that regard.  Hopefully the following information will help you to decide.

Classification

Sideneck turtles are classified in the Testudine sub-order Pleurodira, while all other turtles are placed in the sub-order Cryptodira.  Approximately 75 species of sideneck turtles are found in Australia (where they form the vast majority of the aquatic turtle fauna), South America east of the Andes, sub-Saharan Africa and Madagascar.

The vast majority of the world’s turtles draw their heads straight back into the shell, largely concealing it within. Sideneck turtles retract their heads on an angle, so that the head is pointing sideways when withdrawn, and both it and the neck remain partially exposed.   This limits the protective value of the shell, and may explain why there are no terrestrial sideneck turtles (mammalian predators would easily prey upon them) and why, outside of Australia, they have been largely out-competed by typical aquatic turtles.

Physical Description

The domed carapace (upper shell) averages 12 inches in length, although particularly large females can attain 18 inches.  The shell is attractively colored in muted olive, gray or brown, and bright yellow-orange spots mark the head.  These fade with age but often remain discernable through adulthood.

Males are the smaller sex and have spotted heads with greenish eyes while females have plain, buff-colored heads and black eyes.

Range

This turtle inhabits northern and central South America, including the Caribbean drainages of Guyana, French Guiana, Venezuela and Columbia.  It also occurs in the upper tributaries of the Amazon River in Columbia, southern Venezuela, eastern Ecuador, northeastern Peru, northern Bolivia and Brazil.  There are unconfirmed reports of small populations in Trinidad and Tobago.

Habitat

Yellow-spotted sidenecks favor quiet, slow-moving waters such as ponds, lakes, swamps, flooded llanos (grasslands), oxbows and the backwaters of larger rivers.

Status in the Wild

This species’ status is largely unknown, but it is collected in many areas for food.   It is listed on Appendix II of CITES and designated as “Vulnerable” by the IUCN.

Click: The Yellow-Spotted Sideneck Turtle , Podocnemis unifilis, in the Wild and Captivity: Natural History – Part 2, to read the second part of this article.

Image referenced from Wikipedia.

 

During our last look at outdoor ponds  I discussed an ideal amphibian inhabitant, the American bullfrog.  Today I’ll introduce a reptile that is equally at home outdoors, the red-eared slider.

A Better Outdoor Than Indoor Pet
The Red-Eared Slider is the world’s most popular pet turtle.  The small green hatchlings were previously sold by the millions throughout the USA, but government restrictions have now limited the availability of animals under 4 inches in length (pending legislation may change that situation in the future).

However, sliders are not well suited to indoor aquariums, as they are very active and females can reach a shell length of 12 inches or so.  A turtle of that size needs a tank of at least 55-75 gallon capacity, along with a very powerful filter to maintain water quality.  Even in aquariums of that size, however, these vigorous turtles are cramped.

Sunlight and Diet
Sliders make interesting, attractive inhabitants of garden pools if given enough space and easy access to sunny basking spots. Like most turtles, they require unfiltered sunlight in order to form the vitamin D that is necessary to process calcium and build strong shells (exceptions to this rule are certain largely aquatic, non-basking species, such as snapping turtles, musk turtles, and soft-shelled turtles).

Red-eared sliders will readily consume Repto-min, earthworms, crickets, mealworms, prawn and canned insects, and will do their best to catch small fishes and tadpoles.  They usually will coexist quite well with larger goldfish and sunfish, if there is ample room for the fish to avoid the turtles.  Adults may consume some types of pond vegetation, but if provided with romaine, dandelion, kale and other greens, they will often leave ornamental plants alone.

Other Turtles
Other turtles of similar habits that do well in outdoor ponds are the Eastern painted turtle, Chrysemys picta picta (and subspecies, such as the Midland, Western and Southern painted turtles) and the various Map Turtles, Graptemys spp.  The largely aquatic musk turtle, Sternotherus odoratus, does well even in quite small pools.

Enclosing the Pond
Semi-aquatic turtles often remain near their pond, even if it is unfenced, but males may move away in search of females during the breeding season, and gravid females will seek out suitable nesting areas.  Bear in mind also that raccoons are very adept at preying upon even quite large turtles.

Useful information on constructing and maintaining an outdoor turtle pond is posted at:
http://www.tortoise.org/general/pondmak.html

 

The responsive ways of North Africa’s massive Spurred Tortoise are well known to private and professional turtle keepers.  Inquisitive and alert, these arid country natives are quick to become possessive of their territories and, sometimes, owners.  They adjust rapidly to changes in their environments – two 80 pounders that I kept in a half-acre outdoor exhibit at NYC’s Prospect Park Zoo never ceased to amaze me, despite having been under my daily observation for years.

 

A few years ago, my mother kept an abandoned 30-pound male free-ranging in her yard until a suitable home could be found for him.  He was adopted by a friend, and in short order took over his yard – digging furiously to get at the dog next store, bullying the owner’s dog and ramming or ignoring anyone save his owner.  He never failed to appear when his owner came home, and walked over to sit near him at every opportunity.

 

In June of this year, a neighbor’s terrier-mix (an annoying, yappy beast, I might add!) got into the tortoise’s yard and, in true terrier fashion, made right for what looked like an easy target.  He managed to bite the tortoise’s front leg – at which point the leg was withdrawn into the shell.  As you may know, Spurred Tortoises have thickly-scaled limbs and immense strength, and use their legs as a shield against predators.  Evolving in a habitat with much larger and fiercer predators that a mere terrier, the tortoise easily pinned the animal between its massive foreleg and shell, and there it remained.

 

Efforts by several strong men failed to straighten the tortoise’s leg and, in fact, seemed to strengthen his resolve.  Water was poured on the animals, also to no avail.  I was unable to get to the scene, and thought an injection of a muscle-relaxer might be required.  However, I first suggested that the animals, being carefully supported, be submerged in a child’s wading pool.  Thankfully, this did the trick and the tortoise released his wrestler’s “scissor lock”.

 

Despite having been gnawed on for over an hour, the tortoise’s leg was unmarked.  The terrier, I must say, seemed eager to do battle once again as soon as he cleared the water from his nose – but his owner had more sense!

 

 

You can read about the natural history of the African Spurred Tortoise at:

http://nlbif.eti.uva.nl/bis/turtles.php?selected=beschrijving&menuentry=soorten&id=374