It’s our fourth birthday! Exotics Keeper has released 48 issues since it was launched back in October 2020. It’s been an interesting journey and “EK” itself has transformed and evolved over time, into what it is today; an international platform that focuses on cutting-edge research to improve the lives of exotic pets across the globe.
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MAGAZINE PUBLISHED BY Peregrine Livefoods Ltd
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Print ISSN: 2634-4719
Digital ISSN: 2634-4689
EDITORIAL: Thomas Marriott
DESIGN: Scott Giarnese Amy Mather
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If you are reading this, you are already a valuable part of this mission. Unlike most of the world, you already admire the misrepresented and misunderstood reptiles, amphibians and invertebrates that we share our planet with. Your enthusiasm is an important tool in changing the opinions of others, teaching best-practice husbandry, applying pressure to governments through conservation initiatives and raising awareness and funds for projects that most “animal lovers” skip past.
If you can do anything on top of your normal day today to help raise awareness for reptile and amphibian conservation, I would love to hear about it. It could be a social media post, a chat with a friend, a donation to a charity, some volunteering, a new blog post, a piece of art or anything that helps change the perception of reptiles and amphibians. If we all
do this, every time a new EK lands on your doorstep or in your inbox, we could create some interesting ripples in the world of herpetology, entomology, ichthyology and more! Share your ideas with us on social media and we’ll be sure to share them with the world.
As I write this, I am preparing for another trip, this time to Morocco. It’ll take a few weeks to get all the content together and into bite-size reels, but we should have some arid enclosure inspiration coming soon. The last months of 2024 are already shaping up to be some of the most interesting yet!
Thank you,
Thomas Marriott Editor
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Every effort is made to ensure the material published in EK Magazine is reliable and accurate. However, the publisher can accept no responsibility for the claims made by advertisers, manufacturers or contributors. Readers are advised to check any claims themselves before acting on this advice. Copyright belongs to the publishers and no part of the magazine can be reproduced without written permission.
Front cover: Eastern indigo snake (Drymarchon couperi) Radiant Reptilia/Shutterstock.com
Scuba-diving anoles use head bubble to stay underwater longer
Recent research has confirmed that anoles are the only known vertebrates to use a head bubble to prolong the period of time they can spend underwater.
A study undertaken by Lindsey Swierk, an ecologist at Binghamton University in New York, has found a link between the use of the head bubble by anoles and the time they remain submerged.
The theory was tested by an emollient being applied to the area that typically expands when the reptiles enter the water, preventing the head bubble being inflated and the practice of ‘rebreathing’ being employed.
These test subjects were found to remain under water for 32% less time on average than the individuals allowed to use the function, showing the assistance the head bubble offers the anoles.
Water anoles (Anolis aquaticus) are semi-aquatic lizards found in Costa Rica and Panama, and while the existence of their head bubble has been long recognised, the new research confirms its role in allowing the lizards to remain underwater for longer.
They have been observed to submerge themselves for prolonged periods of time to both hunt for prey and to avoid predators. The ability to ‘breathe’ under water with the aid of the head bubble allows them to remain safely hidden long enough to evade predators.
Tourists
spot newly described Madagascan chameleon species
A species of leaf chameleon new to science has been spotted in Madagascar, making an exciting addition to the recorded wildlife of the island’s embattled ecosystems.
The tiny species, measuring just over the length of the top of a forefinger, was brought to the attention of scientist Miguel Vences from the Technical University of Braunschweig in Germany and his colleagues when they noticed photographs of the species posted online by tourists.
With the assistance of local guides Andolalao Rakotoarison and Alida Frankline Hasiniaina, the team was able to find the first individuals, leading to the confirmation that the species was yet to be scientifically documented.
The new discovery has been named
Brookesia nofy, joining the Brookesia genus made up of minuscule leaf chameleons, and taking its name from the littoral forest site it was spotted in. These coastal forest areas of Madagascar are rapidly disappearing, making every species a precious and endangered treasure.
Tadpoles found not to defecate to avoid contaminating their watery habitats
New research into the behaviours of Eiffinger’s tree frog (Kurixalus eiffingeri) tadpoles has solved the mystery of how the species survives in the tiny water enclaves where they hatch.
The species is found across two Japanese islands, Ishigaki and Iriomote, and researchers from Nagoya University have taken huge strides in understanding the biological adaptations of the frog in its earliest stages.
By laying its eggs in tiny pockets of water in trees and other isolated areas, Eiffinger’s tree frogs provide their offspring with a very early challenge; surviving as one of many in a relatively miniscule area. The new study has revealed that one of the key ways the tadpoles are able to survive in these conditions is by not defecating in these early stages.
This behaviour prevents the build up of toxic substances that when released in a larger body of water would be harmless to the young, but if contained in the small bodies of water inhabited by Eiffinger’s tadpoles would be enough to kill them.
Instead of releasing their waste into their surroundings, the tadpoles are able to store it in their intestines for months at a time, aided by their ability to tolerate high levels of ammonia in their bodies which were detected by the research team.
While remarkable in their own right, these findings have wider implications for conservation efforts surrounding the Eiffinger’s tree frog and other species living in similar habitats. Bun Ito, a special research student at the university, said: “The discovery of frogs that have successfully adapted to the unique environment of small water holes reveals a more complex ecosystem within these tiny habitats than we initially imagined. Protecting biodiversity necessitates the preservation of these microhabitats.”
Tokay geckos’ ‘sixth sense’ discovered
Scientists have discovered a ‘sixth sense’ possessed by tokay geckos that allows them to sense vibrations in their surroundings, adding a new and complex dimension to their ordinary hearing.
Biologists at the University of Maryland discovered that the gecko’s inner ear mechanism, typically associated with balance, can detect vibrations that travel through the ground and water. It gives the species the ability to detect vibrations at a far lower level than their ordinary hearing function, adding a valuable extension to their hearing ability.
The existence of the mechanism could provide scientists with a fascinating insight into he evolution of reptiles and how their hearing functions have adapted and diverged as a result. It suggests that as they transferred from aquatic to terrestrial species, lizards experienced gradual changes to their hearing systems which are still evident in the dual function now discovered.
The research team responsible for the research hope that it may lead to similar discoveries in other reptiles and even in mammals including humans.
Dawei Han, postdoctoral researcher at the University of Maryland, said: "The implications of this research extend beyond the world of reptiles," Han said. "As we uncover these hidden mechanisms, we're also gaining a richer and more nuanced picture of how animals perceive and interact with their environments -- and potentially, new insights into our own sensory experiences."
Case of mistaken identity delays discovery of new fanged frog species
For decades, specimens of a fanged frog have been seen and collected, with smaller individuals identified as juveniles. New studies have shown that these ‘juveniles’ are an entirely different species.
Despite its close resemblance to the Luzon Giant Fanged Frog, Limnonectes cassiopeia, is genetically distinct, while the males sport similar large bony growths in their mouths that resemble fangs.
The new find is the third species of fanged frog known to exist on Luzon, the largest and most populous island in the Philippines. Working from previous studies on fanged frogs undertaken at the University of Kansas, lead author of the study Mark Herr was able to discover that, despite looking remarkably similar to the other amphibians, Limnonectes cassiopeia was actually a separate species, with their smaller, white toe discs setting them apart from other species that have grey tow discs. This distinction makes the new species easy to identify once a person knows what to look for.
This defining physical feature has given the species its name; Herr was reminded of the Cassiopeia constellation when looking at the white toe discs.
After establishing the existence of the species, the research team now hopes to study its behaviour and how it might set it apart from other fanged frog species that share its island home.
UK zoos join international efforts to reintroduce rare bird to the wild Thirty-six years ago, the sihek bird was seen for the last time on the North Pacific island of Guam. Ever since, the species has been declared Extinct in the Wild by the IUCN.
Now, keepers from ZSL’s London and Whipsnade conservation zoos have flown to the United States to help in hand-rearing a female chick that hatched at Sedgwick County Zoo in Kansas in April of this year.
The tiny chick is vital to the survival of the species, offering its last hope of returning to Guam after being wiped out following the introduction of the brown tree snake. The remaining 141 siheks in the world are all currently under human care.
The current conservation initiative aims to establish a temporary wild population on the island of Palmyra Atoll which has no invasive predators. Eventually, the participants plan to return the birds to Guam.
Claire McSweeney, a bird-keeper at Whipsnade Zoo who made the trip to Kansas, said: “This is my second year caring for sihek hatchlings at Sedgwick County Zoo as part of the Sihek Recovery Project.
“Along with my colleague from London Zoo, we’ve been caring for the chick around the clock, from feeding and weighing the bird to monitoring its health, sometimes for twelve hours at a time.
“As the numbers of siheks are so low, there’s a risk of poor fertility among the females. The fact that we already have one chick who is doing so well is such a positive step for the recovery of the species.”
More chicks are due to hatch in the coming weeks, with nine planned for release onto Palmyra Atoll later this year. The chicks will be carefully monitored until breeding pairs are established that can hopefully one day raise wild chicks that will give the species a promising future in their original home.
Written by Isabelle Thom
Websites | Social media | Published research
Each month we highlight a favourite website or social media page
THIS MONTH IT’S: ZEN HABITATS
At Zen Habitats, the mission is to improve the standard of reptile care by providing high-quality products and exceptional service. Check out their blog on Ferguson zones for some great information and tips.
www.zenhabitats.com
A BIG FROG IN A SMALL POND
Lauren Suryanata V/Shutterstock.com
Huge, lime-green frogs, bouncing around the interior of sub-Saharan Africa are a spectacle for any wildlife filmmaker, making the African bullfrog (Pyxicephalus adspersus) a well-known amphibian across the world. It is a ravenous predator, devoted parent and miraculous survivor in harsh conditions. For a long time “pyxies” (a colloquial term inspired by the bullfrog’s scientific name) and “pacmans” were grouped in terms of husbandry, however, there are some stark differences in the natural history of these two very distant groups of amphibians.
A frog in the throat
The African bullfrog (Pyxicephalus adspersus) is one of the largest frogs on Earth. Weighing up to 1.5kg and measuring up to 30cm, these bulky frogs are remarkable. Unusually for frogs, the females are much smaller than the males and will grow to about half the size of an adult male. This may help with amplexus by allowing the dumpy and clumsy frogs to grip onto a female much easier during breeding.
Both sexes have ravenous appetites and will feed on almost anything they can fit in their mouth. They can do this due to their two large “fangs” on their bottom jaw which protrude upwards like teeth and help grip and hold prey items before
the frog consumes them. They are one of few amphibians capable of delivering a painful bite.
From termites to small mammals, the frogs will overpower just about anything they can. One case study even recorded a giant bullfrog eating 17 highly venomous juvenile Rinkhals ( ), possibly in a single sitting, without facing any adverse effects.
African bullfrogs have a beastly reputation and some otherworldly adaptations to surviving in harsh environments. Like many arid frogs, they can develop a thick
A Big Frog in a Small Pond
Zaruba Ondrej/Shutterstock.com
layer of mucous to combat water loss during estivation. During dry periods, they will dig burrows into the soil and form a protective layer which holds in moisture and remains dormant for months (sometimes years!) at a time.
Giant African bullfrogs are exceptionally long-lived frogs. Although a typical captive lifespan is 20 – 30 years, there have been reports of males living up to 50 years old. While this happens frequently in some lineages of salamander, it is unusual for frogs. With excellent care, the keeper should expect to have their animal for multiple decades and potentially generations.
Did you know? Pyxicephalus roughly translates to ‘box head’, referencing the bullfrog’s bulky morphology.
Keeping African bullfrogs
African bullfrogs require similar care to the Cranwell’s horned frog (C. cranwelli). In the wild, both species experience dry periods and live in savannah and woodlands, however, the African bullfrog experiences slightly cooler and drier conditions. Both species naturally aestivate, but the novice keeper should probably consider avoiding this process. Most keepers therefore recommend maintaining humidity above 70% and allowing constant access to water.
Giant African bullfrogs are possibly more active than horned frogs too, occasionally hunting for prey instead of waiting
in ambush. African bullfrogs typically have one “home” burrow and will scavenge for food within 20m of their burrow. Therefore, African bullfrogs should be provided with a reasonably large terrarium to move around freely. A 90x45x45cm glass terrarium is suitable for a single adult male. Females and juveniles can be housed in something slightly smaller. Many hobbyists will opt for plastic tubs to house bullfrogs. These put practicality and affordability ahead of aesthetics but can certainly do the job.
African bullfrogs do not “sleep.” Whilst a captive frog may appear reasonably stationary throughout the day, it may be more active at night. Alternatively, unusually active frogs may just be switching their hunting behaviours and activity levels to suit the environmental conditions they are in. Because of this, it is important to create an enriched and varied enclosure. Today, most hobbyists opt for a paludarium setup for these frogs. Whilst seasonally appropriate enclosures may be more suitable, switching between a paludarium in summer and a terrarium in winter, a well-constructed paludarium can certainly meet the needs of a giant African bullfrog.
Enclosure leapfrog
African bullfrogs can be housed in the simplest of enclosures, in a plastic tub with a freshwater bowl and plenty of substrate. However, it is far more enjoyable for keepers to create a visually interesting exhibit to experience a wide range of natural behaviours from the
A 90x45x45 terrarium is perfect to build a 70/30 land-to-water paludarium setup. This enclosure will provide more reliable water quality, less need for spraying/misting, the opportunity to offer aquatic prey, safeguarding against aestivation/
Martin Hejzlar/Shutterstock.com
drying out and an excellent display.
The keeper should begin by dividing the enclosure with a glass panel and sealing it with aquarium-safe silicon. The larger land area should have a drainage layer (ProRep BioLife and Lucky Reptile Hydrodrain are our favourites) and be topped with some fine mesh and several inches (or as much as possible) of natural substrate such as BioLife Forest or EcoEarth and topped with sphagnum moss and leaf litter. This area will capture water, so the keeper should consider creating access for drainage. An acrylic tube leading to the base (but not touching the base) will allow the keeper to use a turkey baster or tubing to draw any excess water from the drainage layer easier than digging into the substrate to remove it.
The second area will be the aquatic section. This should operate like a shallow fish tank, a submersible water filter or ExoTerra “Turtle Filter” can be placed in the water. Water should then be directed back into the aquatic section (trickling over some cork bark or rock formation is an interesting way
to do this). Pebbles and riverbed sand can then be used to bulk out the water area and provide access in and out of the water.
Top the enclosure off with a Zone 1 Eco-T5 from Reptile Systems and a strong LED grow light to add bright visible light and the enclosure is complete.
Raining tads and frogs
African giant bullfrogs are philopatric in the wild, meaning they will return to a particular breeding site each year. Breeding is explosive and quick. It typically occurs after a dry period, when there is around 2 days of heavy rain resulting in at least 3 inches of water. The frogs will congregate in temporal pools and ditches, where competition is fierce. Dominant males will protect their territory in the centre of a breeding pool (and fight to the death to hold it), while less dominant males gather at the water’s edge. Males will also protect their offspring to give them the best chance of surviving the often-brief rainy seasons, even digging canals to provide access to fresh water.
will typically select the largest male in the centre of the pool to breed with. Amplexus happens quickly and lasts just 15 minutes. Next, up to 3,000 eggs are deposited in the shallow water. Less than 48 hours later, the tadpoles emerge and begin creating schools that, over time, merge into one huge mass of tadpoles.
The tadpoles can take two to four weeks to metamorphose into juvenile frogs. At this point, the young frogs leave the breeding pools to find burrows and humid areas to hunt from and avoid predation from larger frogs.
Whilst these behaviours are truly fascinating in the wild, they leave the breeder with thousands of juvenile frogs to feed. The process is quick, success rates are often very high and cannibalistic frogs must be separated quickly. This is partly why African bullfrogs are so affordable in the hobby. It is not advisable to begin breeding these frogs without a sincere commitment to a more commercial venture and obvious routes to new homes.
Females
SPECIES SPOTLIGHT
The wonderful world of exotic animals
Japanese Fire Bellied Newt (Cynops pyrrhogaster)
The Japanese fire bellied newt is a primarily aquatic amphibian found in cool freshwater ponds and streams throughout Honshu, Shikoku and Kyushu in Japan. In the wild, they are poisonous and contain high levels of tetrodotoxin which they build from their diet.
Fire bellied newts live in surprisingly cool water, making them reasonably unique amphibians to keep. Instead of maintaining amicably warm climatic variables, the keeper should ensure that water temperature doesn’t exceed 20℃. In most homes, this is quite achievable in a water tank, with room temperature water.
Fire bellied newt husbandry should not be underestimated. Their ease of care was perpetuated by the aquatics hobby for years in the early 00s as “cold water” is seemingly straightforward. However, fire-bellied newts should be given access to
UVB, a live food diet and a land area with opportunities to burrow and aestivate if needed. Add to this that they can live up to 30 years in captivity and should be hibernated for optimal health and their care becomes more complex than a goldfish.
Fire-bellied newts will breed without hibernation, but the temperate climate of Japan sees cold winters in which most newts will bury into decaying matter to avoid frosts and freezing water. Therefore, some seasonal fluctuation should be provided. “Room temperature” is perfect during spring and summer, but the keeper should consider housing their newts in the coolest room in the house.
Deeper water will allow for cooler temperatures under UV lighting. So, a 60x45x45 fish tank is a good choice during summer, with a paludarium becoming more appropriate in winter. Aquatic prey such as blood worms and brine shrimp should comprise most of the diet, while terrestrial prey like microcrickets, bean weevils and chopped worms can make a refreshing change. The keeper should seize the opportunity to gut load and supplement terrestrial prey where possible.
The water should be clean, and a good quality filter must be used. Although wild Japanese fire bellied newts occupy fast-flowing streams, they are typically isolated to pockets and pools with less current. Therefore, the keeper should avoid filters that create a strong current.
NutriRep™ is a complete calcium, vitamin & mineral balancing supplement with D3. It can be dusted onto all food sources including insects, meats & vegetables. No other supplement is required.
INSIDE THE INDUSTRY FISH SCIENCE
Interview with Andy Fahy, Marketing Manager at FishScience
Why do we feed insect-eating fish, with fishmeal?
Q Can you tell us about the history and natural progression of FishScience?
A FishScience was first founded in 2013 by Dr David Pool, an industry professional and esteemed academic in fish biology. Dr Pool received instant recognition for his ground-breaking formulas that utilise insect meal as their primary protein component, alongside other expertly-selected ingredients.
The motivation behind launching FishScience was quite simple. “Why do we feed insect-eating fish, with fishmeal?” David asked himself. Most commercial fish foods at the time would use unsustainably farmed fish derivatives as a cheap form of protein, instead of actually implementing real, natural components to create a naturalistic diet. At this point, David discovered the miracle of “calci-worms.”
He began developing more and more natural diets and with black soldier fly larvae (calci-worms) being such an integral part of many of the FishScience formulas, David soon attracted the attention of industry giants, Peregrine Livefoods. Now, the brand is owned, produced and distributed by the wholesaler, who are experts in breeding insects and general livefood nutrition. Dr David Pool
remains a specialist product development consultant providing his longstanding expert insight to construct and refine new and exciting formulas.
QWhat is so special about FishScience?
A Perhaps the most notable “stand-out” feature of FishScience is the use of insect meal. Most commercially available fish foods, particularly those that are set at lower price points, use fish meal as their primary protein component. They encourage insectivorous fish to eat flakes made from other fish, not insects. Not only is this completely unnatural, but it provides sub-par nutrition and encourages unsustainable fishing practices.
The insects that are used in FishScience is the proteinrich superfood Hermetia illucens, the larvae of the black soldier fly. These grubs, referred to in the reptile industry as “calci-worms” due to their high calcium, protein and nutrient content are already consumed across the world by people and their pets. Calci-worms, weight-for-weight are arguably the most nutritious insects available on the market. In fact, they are already widely consumed by people across the world as a healthy snack and as a protein component in main meals.
Q What products are in the range?
A There are over 70 individual products in the FishScience range spanning pond foods, tropical foods, speciesspecific foods and more. Within these categories are purpose-built foods such as Coldwater Pond Foods that use wheatgerm to lower the protein content during the colder months, resulting in less waste produced by the fish and better water quality amongst other benefits. Tropical foods are also grouped into flakes, pellets and tablets and come in a variety of sizes from “micro” for fry and tetra to “wafers” which are large items with added oak wood, ideal for Corydoras.
Species-specific lines are also available for Betta (floating granules with a high insect-meal content to mimic their wild prey), fancy goldfish (slowly-sinking pellets that allow fish with limited mobility to feed efficiently), shrimp sticks (vegetable-rich sticks that sink for targeted feeding) and much more.
FishScience also offers a range of Cichlid foods in a range of sizes. These are broken down into Malawi and general Cichlid foods so the keeper can be sure they are selecting the very best product for their animals. Each product has been carefully crafted to meet the nutritional needs of the fish that it feeds.
Q FishScience values sustainability, could you tell us a little more about this approach?
A As mentioned, insect meal is a far more sustainable and environmentally friendly source of protein than fish. Insects can be farmed quickly and transported far more easily than fish. However, the other ingredients found within FishScience products are also sourced from sustainable methods and the use of natural products such as Spirulina, carrot and Chlorella algae provide nutrients in the most organic way possible. Other “superfoods” such as garlic are also added to boost the immune system of the fish eating it, without the need for artificial chemicals.
Insect meal is a far more sustainable and environmentally friendly source of protein than fish.
THE NEW AGE OF LIGHTING AND HEATING
By Roman Muryn C.Eng
Vlad Linev/Shutterstock.com
Reptile lighting is constantly evolving. Whilst today’s keepers have always considered reptiles to be ectothermic and reliant on heat, the methods with which we provide such heat and light have changed drastically over the last 50 years. Now, we strive to replicate the sun’s radiation as closely as possible and newer products allow us to replicate the major wavelength groups. Whilst we can measure UV (UVi) and visible light (Lux), measuring the strength of infrared ra-diation (Power Density PD) has not been in the herpetologists’ tool box. Hitherto, measuring heat has been the proxy for sunlight strength. In the following article we explain why this new parameter has our attention.
The Basics
The sunlight spectrum (280nm – 3000nm) can be broken into three wavelength groups; ultraviolet light (280nm-400nm), visible light (400nm-700nm) and infrared light (700nm-3000nm).
The shortest wavelength group is ultraviolet. This includes UVb, an important facilitator for Vitamin D3, calcium and management of the immune system, but can (in excess) cause cancer. UVa is also used by our reptiles and is recognised as facilitating vision at wavelengths that we humans cannot see.
Bright visible light is the only part of the spectrum we can see. It offers vision, triggers the circadian cycle and balances hormones that consequently improves mood.
The longest wavelengths are infrared. These have subgroups, IRa, IRb, and IRc, which are also called Near Infrared and Far Infrared. IRa is physiologically important because it is able to penetrate into the dermis (below
the surface of the skin) and heat it internally. It helps the production of nitric oxide. Research has shown that nitric oxide helps functions in the nervous system such as digestion. It may also encourage the release of hormones, including growth hormones and insulin and helps to open blood vessels to improve blood flow. Far infra-red mostly shares its energy through conduction and convection, making things warm to the touch.
Radiated wavelengths spanning the full solar spectrum from 280nm to 3000nm work together to provide full spectrum benefits. Thus, all wavelengths must be represented to simulate the sun. Whilst there are no single products that perfectly replicate the complete solar spectrum, hobbyists will typically use a combination of lamps in the best vivarium set-ups.
These are; one for ultraviolet D3 provision (usually a tube such as an HO-T5 D3) another for visible light (LED spot light or an HID halide lamp) and a third for Near Infrared (IRa) (usually a tungsten/halide/incandescent lamp).
THE SUNLIGHT MODEL
SMARTS Sun Model
Air Mass 1.5 or 42° altitude
TYPICAL TUNGSTEN HALOGEN
2500K tungsten emission model with glass attenuation
TYPICAL CARBON HEAT PROJECTOR
Black body at 900K typical for a heat projector
TYPICAL CERAMIC HEATER
Black body at 500K typical for a ceramic heater
The Experiment – “What light would a reptile choose if given a choice?”
Over the course of three years Roman Muryn has studied the usage of basking spots for various different species of reptiles. He used dozens of bulbs; MVB Mercury Vapour Bulb (3 sizes, 2 brands), Tungsten halogen (1 crate of assorted Powers, Kelvins and shapes), HID Halide (several brands and powers including UVB producers) and Carbon filament heat projectors (4 items tested, 3 brands). Taking 1000s of photographs, he recorded the frequency that a basking spot was visited by the following species: Bosc monitor (Varanus exanthematicus), bearded dragon (Pogona vitticeps), painted agama (Laudakia stellio), collared lizard (Crotaphytus collaris), desert iguana (Dipsosaurus dorsalis), Italian wall lizard (Podarcis sicula campestris) and ackie dwarf monitor (Varanus acanthurus).
The experiment involved a purpose-built, 8-foot vivarium offering three identical basking positions. Each position had a UVb tube (T5 HO 12%), a visible light provision (E27 LEDs, Halides and MVBs) and an IRa provision (E27, many forms of tungsten/halogen and incandescent bulb). Each basking spot had exactly the same mass and material, a thermostatically controlled basking “rock” at 40℃. Each basking area also had similar furniture and air flow. A clock was used to co-ordinate activity, location, with the thermal data logger and video.
Many combinations of lamps temperatures and powers were evaluated but the earliest results were baffling and not what had been expected. Here is an example to demonstrate the problem. The balanced temperatures were 40℃ on the basking spots. HID halide lamps are favourites for lighting enclosures especially in Europe, so 2 different ones were being assessed, the third lamp was an MVB lamp. The MVB was by far the most visited basking spot by the lizards, but why?
Eventually a combination of lamps and powers was
AMALGAMANTED 3 LAMPS
CYCLED IN 3 POSITIONS
June 8, June 10, June 11 2020
#1 35/942 HALIDE
#2 100W MVB
#3 35W MDL
established where all the lamps were visited with equal frequency. Tests included frequently switching lamp positions to reduce the favourite spot and other preferential effects.
It was about that time that Roman was having his solar panels checked. The engineer was using a meter to measure actual solar power. It seemed that the use of this meter would enable actual lamp power (as opposed to temperature) to be measured directly during the vivarium experiment.
Tungsten halogen lamps are “black Body” light emitters through incandescence just as the sun is!
An RS Pro ISM 400 solar power meter was obtained and measurements were taken. Units of solar power are in watts per square metre, a standard engineering metric. (w/ m²) and defined as Power Density (PD).
Note that LEDs lamps, Halide lamps and MVB lamps are not “black body” emitters of light, and readings taken with the ISM 400 have yet to be calibrated.
Then there was the “light bulb” moment. The balanced lamp set up noted above, gave the results as shown in the table below using the new meter. Later tests showed that the halide lamps were avoided simply because they were too strong at the distances used during testing. It was not the temperature of the basking spot that mattered to the animals, it was the intensity of the lamp that they were responding to. Power density matters and can now be measured.
Later work showed that whilst the ISM 400 meter was quite satisfactory for measuring IRa from tungsten halogen lamps, provided the lamps were measured stand alone.
It was not the temperature of the basking spot that mattered to the animals, it was the intensity of the lamp that they were responding to. Power density matters and can now be measured.
Several people were asked to identify at which point they could feel a tungsten lamp warming their skin. Unsurprisingly, the first gentle warmth could be felt at about 200 w/m². This optimal power density can be felt on the back of a hand as a barely perceptible warmth.
Distance about 33cm
Power density with RS ISM 4010
50w tungsten alone Just visible light
Changes in sunlight
The sun comes to visit us every day. It arrives at dawn and completes its tasks at dusk. In the morning it is on the horizon and its light has the longest path to travel. As day progresses, the light has a shorter path; it is closest to us at midday. The distance the suns light has to travel changes considerably.
The atmosphere is not pure. It has dust, particles of pollution, Ozone and water vapour. All of these molecules act upon the light in different ways; the shorter the wavelength, the more it is blocked. So, at sunrise and sunset when the sun’s light has its longest path, the shortest wavelengths are most impeded. That is why light in the morning and evening has more red content. What we don’t see, is that early sunlight also has as a bigger proportion of infrared. At midday, when the sun is overhead, it has the shortest path to earth and so the greatest energy is received (visible light and UV are at their strongest).
The graph shows that visible light fluctuates significantly over the day, but infrared remains comparatively stable. This means that the sunlight a reptile is exposed to at 7am is very different in its makeup to the sunlight the reptile may be exposed to (or actively avoid) at mid-day. Most diurnal reptiles are active in early mornings and late evenings, when the animal can receive the maximal IR without the strongest UV and visible light energy being present.
It is now possible to weave the threads of the above dialogue together. We have learned from the experiment that using the temperature of a basking spot does not help establish the best basking criteria. Instead, knowing how strong the irradiation from a lamp is will give better husbandry guidance. The experiment settled on about 250 w/m² as a preferred PD (Power Density) for IRa.
Applying Results to Herpetoculture
In the UK, on a mid-summer day, the 1.5 AM sunlight standard occurs at about 9.30 am. The value measured around that time is 850 w/m²total solar power (PD). We acknowledge that at 9.30am, it is becoming rather late to look for British herpetofauna.
From the sunlight pie chart, we read that 42% of the power from that reading was IRa. Therefore, the IRa content would have been about 360 w/m². (850 w/m²x0.42) In practice, we would set up a lower PD in the enclosure to replicate an earlier morning PD.
After some 3 years of experimentation, it was realised that the intensity of the light is important. An instrument was selected that could measure sunlight power; the RS Pro ISM 400. Experimentally, 250w/m²for IRa was found to be about right for reptile basking. This also aligned with medical papers noted by several academics.
(Piazena H, Kelleher DK, 2010)
Meteorological data and physics tell us how sunlight changes during the day. Field work informed us that the best herping is in the morning when the sun is less intense, and that IRa in the morning also had a PD value of the same magnitude as found in the captive experiment. The numbers aligned!
Lamp timing and power
Interestingly, if the keeper can achieve the correct power density from their light, they will also likely achieve the correct temperature. The Reptile Lighting FB group has developed irradiance charts that depict how the light power (PD) is irradiated by a lamp. The example charts above show the spread of IRa from various commercially-available lamps. The black/blue line shows where the power density matches that of recommended PD levels. Different lamps can reach this power density at different distances. It is hoped that data like this will be printed on the side of lamp packaging in the future.
The above chart was produced by Quentin Dishman and the irradiance charts and measurements were produced by Thomas Griffiths.
Using meteorological data, Roman and Quentin Dishman, along with various other herpetologists across the world, are already identifying power density for different regions. A methodology is being developed for recommending power densities and has so far been promising. Hobbyists can implement some of this research immediately. Roman has simplified the process (based on his experiment) stating:
For UV light
Turn on the UV lamps from 9.00 till 15.00.
Set power levels measured by the SM 6.5 as recommended by Ferguson zones.
For visible light
Turn on visible lamps from 8.30 till 19.00
Sunlight reaches over 100,000 Lux and that’s not possible, not necessary, nor practicable in the vivarium. For the basking spot provide a lamp as bright as possible preferably over 20,000 Lux. The experimental vivarium had 40w LED spot lamps producing over 40,000 Lux. Provide background light also, strip light LEDs work fine.
For IRa light
Turn on Tungsten/halogen infrared lamps from 8.00 till 21.00
PD recommendation is about 200 w/m²for northerly cool climate animals and 350 w/m²for bright sunlight, midday desert animals. It is important to remember that basking strengths when we encounter animals are often lower than that normally quoted for midday sunlight power.
Adjust times proportionally for each season. Whilst the light doses are now outlined, the other part of the vivarium set up should provide shade, substrate, humidity, ventilation, retreat and security. A simple summary of just a few of the benefits each wavelength group brings.
UV wavelengths
290 - 400nm
• D3 synthesis through UBb
• Immune system management
• Fungal and bacterial infections
• Signalling
• Egg development
Visible light wavelengths
400 - 700nm
• Warmth
• Drying and heating to aid in shedding
• Fungal and bacterial infections
• Raise temperature to manage viral infections
• Parietal eye stimulus
• Melanopsin control
• Hormone management and production
• Circadian cycle
• Communication
Temperature control
IRa (Near Infrared wavelengths)
700 - 3000nm
• Sub-cellular Melatonin
• Digesting food
• Drying and heating to aid shedding
• Raise temprature to manage viral
• infections
• Healing
• Pineal gland stimulus
• Egg and foetus incubation
• Protection against UV
• Nitric Oxide
• IRa also stimulates ATP production in mitochondria
Once the lamp power is established, and provided that the enclosure volume is appropriate, then the basking spot temp erature should follow through. However, a simple on/off thermostat is still required. The sensor is placed in the cool spot, one which offers the necessary thermal gradient, out of the direct light. This would be set so that if for some reason there is an overheating problem and the cool spot gets too hot, then the thermostat kills the heat lamp(s).
In the experimental vivarium, the summer brought extra heat and a thermostatically controlled fan was used to suck in fresh cool air from outside.
Reptiles perceive light differently to humans.
To mimic sunlight, the keeper must provide a source of ultraviolet light, a source of visible light and a source of infrared light in the right doses.
Actual sunlight changes very little across the world at the same latitude, it is the environment that changes the composition of light and the consequential local temperatures.
UV and visible light change the most throughout a day, infrared remains relatively stable. This can be mimicked in a terrarium.
Providing the correct power density is just as important as providing the correct light spectrum. It is just like medicine; dose is important and dose varies from patient to patient.
It is possible to provide the correct power density with lighting that already exists on the market. However, the keeper must select the wattage of each lamp to balance them effectively, dimming is not really required.
Piazena H, Kelleher DK. Effects of infrared-A irradiation on skin: discrepancies in published data highlight the need for an exact consideration of physical and photobiological laws
KEEPING AMERICA’S LARGEST SNAKES
Husbandry and breeding strategies for Eastern indigo snakes.
The Eastern or “Florida” indigo snake is the longest native snake in North America. Growing up to 8 feet in length and sporting a bulky head structure, these robust colubrids are iconic yet misunderstood. Hobbyist breeder and Senior Keeper at Birmingham Conservation and Wildlife Park, Adam Radovanovic aims to change this by breeding the species for zoological collections across Britain.
Indigo snakes
The Drymarchon genus contains several species of large colubrids from the Americas. The bulk of the genus is found in Latin America, where they are often referred to as “cribos”. The largest of these species, the yellowtailed cribo can reach a whopping 12 feet in length and is notoriously feisty. Further north, Drymarchon diversity reduces as tropical climates become rarer. One species, D. melanurus, can be found in Mexico. Further north, the
Eastern indigo snake is native to a restricted range in the southeast USA.
“They used to be very common throughout the American South including Florida, Georgia, Alabama, Mississippi and South Carolina. Today, they are only found in southern Georgia and part of Florida” explains Adam. “Their habitat is open forest, scrubland and sand hills where they use
the burrows of gopher tortoises as refugia. This may have something to do with their declines as gopher tortoises are also very threatened and listed as Vulnerable.”
Adam first began working with indigo snakes 26 years ago when he was volunteering at Birmingham Wildlife and Conservation Park. “There was a pair of 6–7-foot Texas indigo snakes that were bought in from Bristol Zoo. It was the first time I’d ever laid eyes on indigo snakes, and I was just blown away. They’re enormous and really cobra-like. They’re super aware of their surroundings and very alert and unlike anything I’d ever worked with before.
Indigo snakes are sexually dimorphic with males typically
being much larger and bulkier than females. “Both our snakes are adults, our male is about 3kg whereas our female is around 2kg, so there is a pretty sizeable difference,” said Adam.
“Other members of the Drymarchon genus are known to be feisty, but the Eastern indigo snakes I’ve worked with have always been alright. Our female puffs her throat out, but our male is a big softie. Most people know them to be well-natured, it’s just their intense feeding response that can make them look a bit fierce. Saying that, I was bitten by an indigo snake during a feeding episode many years ago and it was pretty bad. They have strong jaws and can deliver a nasty bite.”
DID YOU KNOW
Drymarchon translates to “Lord of the Forest”
The Eastern indigo snake is the longest native snake in North America.
Development of agriculture has destroyed up to 97% of the Eastern indigo snakes’ native habitat.
Invasive Burmese pythons threaten wild indigo snakes with a lung parasite that can be carried by the pythons but is life-threatening to indigo snakes.
Wild indigo snakes eat a varied diet, but this is mostly comprised of other snakes.
Listed in 1978, the Eastern indigo snake was one of the earliest species to be awarded protection by the Endangered Species Act.
Conservation
Despite their iconic status as North America’s longest snake, there is little research into the conservation status of the species. Yet, researchers and organizations working directly with the species believe there is serious cause for concern.
“They have an interesting story” Adam added. “They’ve been extirpated from most of their range and people really don’t understand much from a conservation perspective. They have disappeared from most of their range and yet are still listed as Least Concern by the IUCN. It would be great to see more collections working with the species.”
The last IUCN RedList Assessment for Drymarchon couperi was in 2007. The US Department of Wildlife and Fisheries recognizes the threats facing the species and has implemented a 5-year plan that will be reviewed next year to conclude their conservation status listing.
There are also some captive breeding initiatives to help protect the Eastern indigo snake. The Orianne Society works with Central Florida Zoo to breed Indigo snakes for release. So far, the organisations have released over 150 animals back into the wild. The
animals are assessed over time, and some are microchipped and tracked so that herpetologists can learn more about their spatial ecology.
This in-situ research is fundamental to the recovery of the species in the wild, however, the legislation protecting them is creating new challenges for zoological collections. It is illegal to cross some state borders with an indigo snake (even a captive-bred specimen) which makes exporting more difficult. “There hasn’t been any new blood since the 1980’s” said Adam.
Captive indigo snakes are starting to show morphological signs of inbreeding, including split ventral scales. This is something that is already appearing in Britain’s adder populations, due to such small numbers in such highly fragmented habitats.
Adam explained: “Some species of snake appear to withstand generations of inbreeding with no issue, or the appearance of unusual morphs and colour variations. Drymarchon couperi is not resilient to inbreeding and this practice almost always causes defects. This means we’ll probably never have an Indigo snake morph breeding hobby and amplifies the need for genetic diversity in captive populations.”
Husbandry
Adam houses his Indigo snakes individually in 6x3x3 feet vivariums. “You need multiple bulbs to create a basking spot large enough for an adult Indigo” Adam added. “I use two 100W spots alongside a Reptile Systems Ferguson Zone 2 EcoT5. Because of the height of the enclosure, they can get 2-2.5 UVI in their basking spot.”
Adam keeps his Indigo snakes at an ambient temperature of 25 - 28℃ with a basking spot of 30 - 32℃. “I don’t keep them too hot” Adam explained. “They’re a temperate species and I like to keep relatively stable conditions year-round. They don’t hibernate and the temperatures in tortoise boroughs are relatively stable, so I don’t provide any significant temperature drops. During winter, the nighttime temperatures will decrease naturally. I also adjust the lighting from 14 hours on and 10 hours off in summer to 10 hours on and 14 hours off in winter. In summer, nighttime temperatures will be around 18℃to 20℃. In winter, these will drop to around 14℃, so nothing too cold.”
Indigo snakes are diurnal but have sporadic behaviour patterns. In the wild, they spend much of their time below ground in burrows. In captivity, they hide in cork bark tubes, artificial caves and other refugia. Adam uses a range of décor for climbing, including branches and cork bark and provides a healthy layer of bamboo and mixed leaf litter to provide extra cover on a substrate of orchid bark. “They do need spikes in humidity, especially during shedding, so orchid bark is a good choice if you’re going to spray them down. I don’t mist or feed on a schedule as it seems unnatural, but I will make sure the humidity sits around 50-60% most the time with occasional spikes up to 80% after a misting.”
One very famous observation about keeping indigo snakes persists within herpetoculture, which has awarded the species an unsavoury reputation. “For some reason, Indigo snakes stink,” laughed Adam. “It might be because they have such a varied diet, but even animals
that are fed on rodents stink. Whatever happens in that digestive process just makes them stink. It’s not a pleasant experience cleaning out an indigo snake!”
Feeding
Adam feeds his indigo snakes on a varied diet incorporating rodents, salmon, trout, chicks and quail. Indigo snakes are notoriously ravenous feeders. As active, diurnal colubrids they are adapted to hunting for nimble prey and thus have an excellent feeding response in captivity. However, there are some considerations the keeper must make before preparing a diet for this species.
Adam continued: “Interestingly, I still need to chop the wings off the quail, even for our adult male. Indigo snake jaws are strong and fixed, so they are limited to what size prey they can eat. For example, a python of the same size could probably eat prey two or three times bigger than what indigo snakes can handle. Those jaws are so strong that our male will disembowel rats and split chicks in half from a single strike. I was bitten by an indigo snake as a teenager and it was really painful!”
Because indigo snakes are so food-orientated, the keeper has a lot of opportunities for enrichment and training. Scent trails, tong feeding, varied diets and other sensory enrichment strategies are all relatively easy to implement. Some Eastern indigo snakes have also been target-trained and filmed solving puzzles and mazes to retrieve food items.
Breeding
Indigo snakes require a somewhat unorthodox breeding strategy compared to other North American colubrids. Adam pairs his snakes in winter, as the daylight cycle shifts and night temperatures cool.
Adam continued: “I breed my indigo snakes every year. The first time I introduced the male into her vivarium, she did have a pop at him. I think it was because it was the first
time she had been in contact with a male. Now, I think they are both used to it and I haven’t had any problems since.”
“Usually when I introduce them, he will become interested in her almost immediately. They are housed separately, but close to each other. At the start of the breeding season, you can see him up the glass and becoming visibly more active. The enclosures are right above each other so I suspect he can also smell the pheromones. Once they are introduced, he will usually try to lock with her pretty quickly. Then, I separate them overnight. Indigo snakes are known to eat each other, so I don’t want to take any risks.”
“Of course, you don’t know if the first lock did the trick, so I will repeat this pairing process every couple of days until the snakes aren’t interested anymore - which usually takes 10 days.”
Indigo snakes have remarkably long gestation periods, lasting around two months. Adam pairs his animals in December and expects to see the clutch by March. Indigo snakes only lay one clutch a year, consisting of around 11-13 large eggs.
“It makes sense, right” adds Adam. “While most other snakes are hibernating, the indigos remain active to protect their eggs. The eggs develop in the cooler period and are laid when temperatures rise. However, even in March, temperatures are pretty cool and you should incubate them relatively cool too.”
“I incubate my eggs at 24℃and they usually hatch after 100 days. Some people incubate warmer but there are anecdotes of spinal kinks in clutches that are incubated too warm. In fact, the Orianne Society incubates their indigo snakes even cooler than I do at around 22.5 ℃ to 23℃. It takes those clutches around 100 – 120 days to hatch.”
Adam keeps the hatchlings in a sterile environment on paper towels to monitor their health for the initial weeks of their lives. As a species that exhibits cannibalism, young indigo snakes will disperse as quickly as possible and often burrow to secure their safety. In a captive breeding context, supplying some hides for security is essential.
“You’ll always get a few pain-in-the-*** animals, but baby indigo snakes are great feeders. Around 80% of my animals were fed for the first time. The ones that don’t are quickly persuaded with the scent of salmon or a chick feather.”
Veterinary issues
Indigo snakes are robust predatory animals capable of thriving in cool temperatures. They are also extremely stoic, making them almost asymptomatic to many illnesses. Because of this, it is not easy to treat an indigo snake. Furthermore, they are known to be sensitive to medical treatments including worming medications and sprays.
Adam continued: “It is not uncommon for someone to have a completely ‘normal’ animal that feeds perfectly one day and dies the next. It is best to avoid all prophylactic treatments as they do not take well to it. Even ivermectin and frontline sprays could cause an indigo snake to keel over. If a snake carries Salmonella or low levels of E-coli it can sometimes do more harm trying to treat it. Of course, if this leads to immunosuppression it should be addressed but it’s not always easy to tell.”
Conclusion
Large snakes will always pose a challenge for private keepers, simply due to their space, diet and electrical requirements. However, some species capture the hearts of keepers with their surprising cognitive abilities. In some respects, these species are easier to maintain and manage as enrichment can be provided in myriad ways.
Adam’s pair of indigo snakes are off display at Birmingham Wildlife Conservation Park and prospective hobbyists may be inspired by their husbandry and exhibit. Others may be left in awe at the sheer size and beauty of the Indigo snake. A select few may even go on to unravel the mystery of the disappearing indigo snakes in North America and support the Orianne Society in their vital captive breeding efforts. Working with misunderstood snakes can produce fantastic contributions to herpetology through “best practice guidelines”, anecdotes, education and exposure in both a zoological and private context.
Patrick K. Campbell/Shutterstock.com
ADDRESSING CROC CONSERVATION ON THE NOSE
By Thomas Marriott with Ranjana Bhatta
The gharial (Gavialis gangeticus) is a Critically Endangered crocodilian isolated to just 14 populations in northern India, southern Nepal and Bangladesh. Despite being considered sacred in some cultures and feeding almost exclusively on fish, human activities have caused the global population estimate to drop to fewer than 900 remaining adults. More shockingly, this figure is double the number predicted 8 years ago. Today, gharial population numbers are increasing and whilst the species is still considered one of, if not the most endangered crocodilians on Earth, conservationists are now working tirelessly to change the future of the gharial. We met Ranjana Bhatta, Founder and Director of Care for Nature at Chitwan National Park in Nepal to learn more about these prehistoric reptiles.
The Gharial
The Gavialidae family contains only two extant species, the gharial and the Sunda gharial (Tomistoma schlegelii). Together, they are very unique crocodilians. Genetically they are sister taxon, but both are only distantly related to “true” crocodiles,
The Gavialidae family is an ancient group of prehistoric reptiles with several more extinct members grouped into the family. Unsurprisingly, the gharial exhibits many of the unique and striking features of its prehistoric cousins.
The gharial has a long, narrow jaw with interlocking teeth positioned outwards to grip fast-moving fish prey, even in river sections with strong currents. Unlike the sympatric
mugger crocodile (Crocodylus parustris), the gharial feeds almost exclusively on fish and sometimes small turtles and frogs. They must catch appropriately sized fish and juggle them into position to be swallowed. Their webbed claws and flat muscular tails are well adapted for swimming and the elongated snout is also very well adapted to move against the water current. Gharials are more aquatic than other species of crocodilians and do not walk far from the water. Although they bask on land, they are always very close to water.
Gharials are also the only species of crocodilian to exhibit clear sexual dimorphism. Males typically have a large growth on the end of their snout, which they develop
when they reach adulthood.
Ranjana Bhatta told us: “Adult males have a round bulblike structure at the end of the snout that we call the ‘Ghara’ which means an ‘earthen pot’ in Sanskrit language.
“Gharials are also very unique crocodilians because of their ecological role and functional distinctness. They are great protective alloparents where the male or the female or both parents continuously guard newly hatched babies coming from several nests at the nesting site and the group of these baby gharials is known as a creche. We have observed female gharial guarding the creche for over two months when monsoon was delayed.”
Conservation Challenges
The gharial is considered an Evolutionarily Distinct and Globally Endangered (EDGE) species, meaning the extinction of gharial would mean losing a whole branch on the tree of life. These determining factors make it a priority for the Zoological Society of London which enlisted Ranjana Bhatta as an EDGE Fellow in 2019. Her work focuses on the reproductivity of gharials in the wild and has been conducted over five years, mainly focusing on the natural recruitment and efficiency of wild reproduction. This research aims to determine whether wild reproduction can stabilize the Chitwan population of gharial.
Sadly, the gharial faced conservation hurdles for many
Author and Editor, Thomas, photographs a gharial protecting its nest.
Addressing Croc Conservation on the Nose
An example of the sandy nesting banks that gharials need.
decades before its EDGE listing and it is thought that the species now occupies less than 6% of its former range.
“Before the 1940s, gharials were found in most of the tributaries of the Ganges, Brahmaputra, Meghna as well as other rivers reaching as far as Myanmar” explained Ranjana. “In the 1940s, the widespread construction of dams changed the river hydrology and it was with these changes that the major declines started. Before the 1940s most fishermen also used hand nets which are reasonably sustainable. However, today, most fishermen use gill nets. These are made from nylon with small holes and are often left in the river for several hours or overnight to catch anything that swims into them. The increased use of gill nets has increased mortality rates of gharials. Both adults and juveniles have long, thin snouts so they are easily trapped and can suffocate from these nets.”
Interestingly, the threats that face wild gharials are so numerous that each population requires a different conservation priority to protect them. In India, infrastructural development poses a huge risk. In Nepal, the threats are slightly different depending on the population.
Ranjana continued: “The nesting banks are very limited in Chitwan right now. In Nepal we currently have two breeding populations, one in Bardiya and one in Chitwan. In Bardiya, the sites are inside the protected area, removing them from human inhabitation so there is less threat from humans, compared to Chitwan. However, irrigation barrages are running close to Bardiya that pose a
major threat to that population.”
“In Chitwan, the major threats are sand mining and gill netting. It is a huge problem in the buffer zone area where the Gharials breed. In Nepal, it is legal to remove sand once certain environmental assessments have been done, but these gharials require very specific sand banks with some slopes and close to the water to nest in. With less sand, there are less suitable sites and the likelihood of finding an area with a steep slope, has proximity to the river and is still protected from flooding, is rare.”
During our walk around the nesting sites, Ranjana noticed some new nesting sites that are on the domesticated elephant trail and had been trampled. Whilst it is unclear exactly how much damage the elephant caused, the excessive pressure on the sand could have easily rendered the entire clutch unviable. “This is a really disturbed area for nesting and, in general, gharials do not like such places,” she added. “But, because of limited sand banks and increased competition among females for nesting sites, they are forced to use them.”
“Gharial body parts, including the ghara and the eggs have been traditionally used by people as medicine” added Ranjana. “There are stories about mugger crocodiles and dolphins. Some tribal people in eastern Nepal consider the mugger crocodile as a deity and they worship the species. Sadly, it’s not the same with gharials. If a gharial is trapped in a fishing net, it will probably be killed by fisherman.”
Breeding
Gharials have a fascinating breeding cycle. Whilst not as territorial as saltwater crocodiles, male gharials typically have their territories within a river system during the breeding and paternal guarding period. Usually, the females are highly social choosing to bask, feed and nest in the same areas, and doing so all year round, so they are not psarticularly territorial.
“The breeding season starts by the end of winter (around January)” explains Ranjana. “At this time, the adults will start to gather at specific breeding sites. By the end of January and into the second week of February, the mating happens. Oviposition happens from the end of March until the second week of April. Hatching typically starts from the first week of June and lasts a few weeks. The latest hatching we’ve recorded in Chitwan was during the first week of July in 2021.”
In January, Ranjana assesses the river system to identify where the breeding population is gathering and where they might nest. In March, she visits the field weekly to monitor the nesting sites. In 2023, she also used camera traps to get a better understanding of the hatching process. In June, she returns to the site to monitor the number of hatchlings from each nest.
Rumaisha Project/Shutterstock.com
“The parents will stay close to the nesting sites where the young hatchlings are until the monsoons arrive,” added Ranjana. “This is usually only a few weeks, which is short for most crocodilians. The guarding mother or father are very defensive for newborn and prefer the highly vegetated area near the shore to provide additional protection from predation for the babies.”
Like all crocodilians, the sex of the offspring is determined by the temperature at which they are incubated. For gharials, an incubation temperature of 32oC will result in a higher percentage of male hatchlings, while an incubation temperature of below and higher of 32oC will result in a higher percentage of female hatchlings. This amplifies the importance of having a wide offering of nesting sites available. If gharials are forced to nest in inappropriate areas, there may be a higher proportion
of a single sex. Furthermore, climate change is increasing surface temperatures and flooding throughout the tropics, including lowland Nepal.
Captive rearing programme
In response to the catastrophic decline of population during 1970s, the government established Gharial Conservation and Breeding Center in Chitwan by government. The nests from the wild are brought into a captive facility where hatchlings are reared until they reach 1.5m in length. They are then released into the river. However, the sustainability of such a programme is under question by conservationists, including Ranjana, who are monitoring the wild populations.
Ranjana explained: “Captive rearing has a major role in bringing a population back from extinction. The gharial population was below 50 individuals in Nepal in the 1970s and remained similar right up until 2004. Captive breeding helped to reintroduce individuals, but this programme has now been running for over 40 years, so there is a major issue regarding the survival rate of released gharials.”
“It is difficult to justify a captive breeding and head-starting programme with such small survival rates. Many scientists, including me, believe that there must be a better solution than depending totally on captive breeding. Maybe a 40:60 of head starting to managing the wild population, may be a better use of resources.”
“The survival rate of wild individuals could be much higher. Those in a head starting programme are in captivity for 5 – 7 years. This gives them adaptation issues, which means they are unlikely to survive in nature. Obviously switching from ex-situ to in-situ, you need data and scientific records, which are just lacking at the moment. Without knowing how a species will survive in the wild, it is difficult to transition towards allowing more gharials to hatch naturally.”
Ranjana is working on developing the data and research on the survivability
DID YOU KNOW
Adult male gharials can reach up to 6m (19 feet) in length!
Despite their fearsome appearance, gharials feed mostly on fish and other suitably sized prey.
Female gharial can lay up to 60 eggs in a single clutch. However, they require very specific conditions to make their nest.
The gharial has suffered an occupancy reduction of 94%. That means it can only be found in 6% of its former range.
The gharial is one of the most ancient vertebrates on Earth, remaining relatively unchanged for millions of years.
True gharials are only found in Nepal, India and Bangladesh where they inhabit a small number of freshwater river systems.
Both males and females act as doting parents, which is rare amongst crocodilians.
Addressing Croc Conservation on the Nose
SURAJEET 96/Shutterstock.com
of wild gharials to hopefully create a more robust method of reintroduction. Whilst the IUCN recognizes that population numbers are increasing, it is difficult to consider the conservation methods used today as a resounding success. By utilizing a holistic approach to conservation, Ranjana’s research may be pivotal in changing the future of the gharial in Nepal.
Potential successes
Whilst conservation strategies are never straightforward, the gharial is now receiving global recognition for its plight. Global population numbers have increased drastically since the 1970s. Despite the fragmentation of populations, which will certainly pose a challenge for the recovery of the species, scientists are discovering new potential habitats and waterways that are being utilised by gharials.
“In Nepal and India, gharial population numbers are increasing,” said Ranjana. “The largest breeding population in the world exists in Chambal River and there are numerous projects working on gharial conservation there. The Gharial Ecology Project in Chambal is regularly monitoring nests
and use telemetry to track gharial populations.”
Although there are signs of potential recovery for the mystical gharial, the future is still uncertain. Currently, seven of the world’s 28 crocodilian species are listed as Critically Endangered by the IUCN. That means almost one third of Planet Earth’s crocodilians, an ancient lineage of reptiles that predates most living things on Earth, are in danger of becoming extinct without drastic intervention. With concerted efforts in local areas, several crocodilian species are seeing population increases as scientists learn more about the threats that face them.
Ranjana concluded: “In Nepal, we used to have gharials in most river systems of the entire Terai (lowland) region, from the eastern to the western parts of the country. Now, they are in just three river systems. I am hopeful that we will identify new populations in western part of country and my proposals for fundraising are successful enough to dedicate resources to understanding more about these animals and to protect their future. To me, signs of success are quite simple. More nests mean more hatchlings and more hatchlings means more potential for breeding adults in the future.”
The “bioactive boom” is over. Today, more people keep bioactive enclosures than ever before and it is somewhat normalized across much of the world. Smaller species, capable of being kept in large naturalistic setups are becoming more popular and even novice keepers are experimenting with the ecological benchmarks of wild habitats to formulate their captive reptiles’ husbandry. This includes implementing more varied and diverse “clean up crews”. The following article explores a range of custodians for every setup.
Arid
Firebrat (Thermobia domestica)
Firebrats are the latest live food craze. They are capable of thriving in extremely hot and arid conditions and are very active, making them an excellent food source for geckos, young agamids and desert invertebrates. In hot temperatures (around 39℃) these tiny insects will breed and provide some supplementary food throughout the year. While they typically eat carbohydrates, as opposed to decaying matter, their presence will help clean up any leftover bran or other detritus that accidentally makes its way into an arid enclosure.
Clown isopod (Armadillidium klugii)
Clown isopods are easily recognised for their bright markings which are thought to be a form of mimicry of the Mediterranean black widow, to deter predators. They come from the coastal areas along the Adriatic Sea, notably Croatia and Montenegro. They are usually found beneath stones and in crevices, where they seek humidity. That being said, these isopods are generally considered a good all-around generalist species, so long as a humid area is available in your bioactive somewhere – which is usually the case even in an arid setup. They reach a maximum size of 21mm and will eat pretty much any organic material available.
These are an excellent choice for arid setups, so long as a small humid retreat is available. P. dilatatus come from Western Europe and North America, and they grow quite large, owing to their name. They eat organic matter similar to most other isopod species and reproduce at a moderate rate. They don’t have a flashy appearance, but are a good choice for their hardiness in drier setups and affordability.
Blue death-feigning beetles (Asbolus verrucosus)
Blue death-feigning beetles are awesome pets in their own right. Sometimes referred to as “ironclad” beetles, these robust, pastel blue insects patrol the Mojave Desert in search of decomposing matter to feed on. When they feel threatened, they will simply “play dead” making them easy to handle, which is part of the reason they are popular “school pets” throughout the US. Sadly, they are
notoriously difficult to breed in captivity, which makes them somewhat unsuitable for a “true” bioactive
Darkling beetles (Tenebrio molitor)
Darkling beetles are essentially metamorphosed mealworms. It is highly likely that most keepers will have encountered these beetles in the past and while they do not make very good feeder insects due to their poor nutritional value, they can make an effective and very affordable clean up crew. They are capable of tolerating a range of climates but will likely be eaten by any insectivorous reptile reasonably quickly. Therefore, introducing them to omnivorous/herbivorous species (desert iguanas, Uromastyx, adult bearded dragons, etc) will ensure they live a little longer. For other species, there is no need to remove darkling beetles unless they are inadvertently making up a considerable portion of a reptiles’ diet.
Clown isopod (Armadillidium klugii) Close to Me Photography/Shutterstock.com
Giant canyon isopod (Porcellio dilatatus) Michael Siluk/Shutterstock.com
Blue death-feigning beetles (Asbolus verrucosus) GypsyPictureShow/Shutterstock.com
Darkling beetles (Tenebrio molitor) Tomasz Klejdysz/Shutterstock.com
Temperate
Pill isopod (Armadillidium vulgare)
These are the common woodlice we see in Europe and the UK. They are hardy and tolerant of some dry conditions, so they should establish well in a tropical or arid setup as long as conditions aren’t too extreme on either end. While the wild type is a bland slate grey, there are a few colour morphs now available thanks to captive breeding, including red, yellow, albino, “orange dalmatian”, or “magic potion”. Whatever the colour, they will all do the same job in the end.
Granulated isopod (Armadillidium granulatum)
This species is also a safe choice for almost any bioactive, favouring a 50:50 dry and moist environment. Keeping the humid area of your enclosure maintained will provide a good refuge for these isopods. They don’t like to be too wet, so they likely won’t be ideal for a tropical setup that needs frequent heavy misting. Younger individuals may be eaten by inhabitants, but they are a fairly large species when adults. They also sport quite an appealing colouration of yellow splotches.
Speckled isopod (Porcellio scaber)
P. scaber is another common species found throughout Europe and with different colour morphs – such as the popular orange and “dalmatian” varieties. These isopods need 70-80% humidity to thrive and therefore will not do well in an arid environment with low humidity levels. They eat and breed well in captivity.
Dermestid beetles (Dermestes maculatus)
Dermestes maculatus is a species of beetle found in every country across the world except in Antarctica. It is most commonly associated with carrion and decomposing flesh and has been known to strip a dead animal to its skeleton in a matter of days. Whilst this doesn’t sound like the kind of animal a keeper would want to introduce to their collection, they only feed on dead animals and meat. For keepers of blue tongue skinks, monitor lizards, carnivorous turtles or messy snakes, this clean up crew can help polish up the remains of frozen thawed food, chunks of meat and other detritus within the vivarium.
Earthworms (Lumbricus terrestris)
There are numerous species of earthworms available as feeder insects. However, the humble European earthworm is the most well established. Just like in nature, these worms break down complex matter into simpler compounds within the soil, essentially making it easier for plants to absorb nutrients. Their tunnels also aerate the soil which allows for better water flow and creates a better environment for roots to become established. Earthworms are very effective clean up crews, making them ideal for large and deep enclosures both indoors and outdoors.
These are tiny hexapods that are found across the world. Collembola is actually one of the ancient lineages, that are no longer considered ‘insects’ and date back almost 400 million years. Because they are found all over the world, they are extremely adaptable and excellent for both tropical and arid setups. They can be cultured within a pot of charcoal and water and provided with grains of dry rice (which then produce mold for the springtails to eat). Of course, if a bioactive set-up is healthy with a good amount of leaflitter or fungus, a single colony of springtails should thrive for many generations.
Dwarf tropical white isopod (Trichorhina tomentosa)
These are usually said to be the most common species chosen for tropical setups with high humidity. Dwarf whites are soft bodied isopods that do not roll into a ball, and reproduce asexually. They are small, but hard workers; efficiently cleaning up detritus from the soil and other areas of the environment. T. tormentosa are most popular for keeping alongside amphibians such as poison frogs.
Millipedes (Diplopoda)
Millipedes make fascinating pets and their detritivore diet also makes them excellent clean up crews. There are countless species of millipede available in the exotic pet hobby and invertebrate specialists will undoubtedly offer more specific husbandry information than this guide can provide. However, there are a few things to consider with millipedes; firstly, some species can be toxic. Species that live side-by-side in the wild will learn to avoid toxic prey, but mixing millipedes with reptiles and amphibians from other parts of the world can result in predation. To avoid this, try picking an appropriately sized species. Secondly, millipedes are ravenous feeders and may feed on terrarium plants if there is a shortage of leaf litter or organic materials in the terrarium. They are best used as clean up crew in large, well-established terrariums.
White worms (Enchytraeus albidus)
White worms are a staple in the aquarist industry and have been since their mass cultivation in the 1940’s former Soviet Union to provide a highly nutritious food source to fish. Today, they are frequently used to feed fish, newts, salamanders and some frogs. This makes them the ideal clean up crew for a paludarium setup, as any worms that fall into the water will wriggle wildly before a fish or turtle snaps them up. They also breed more prolifically than earthworms, so having them available in a frog tank can make for a more reliable supplementary food source. Once introduced to the terrarium, the worms should breed and thrive providing that the soil pH is reasonably neutral (6.8-7.2) and constantly moist. White worms will feed on a range of decaying matter but supplementary bread crumbs can help the population establish or grow.
FASCINATING FACT
Natural History Museum Herpetology Collection
The Herpetology Collection at the Natural History Museum, London is one of the longest-maintained collections in the world. It was founded in the 18th Century and now contains 200,000 specimens, including
8,000 type specimens. A type specimen is used to describe or reinforce a description of a species, making the Natural History Museum collection one of the most important in the world.
