Sneak preview of A Guide to Australian Monitors in Captivity

A Guide to…

Australian

MONITORS

in Captivity

By Dr Danny Brown

BVSc (Hons) BSc (Hons)

SNEAK PREVIEW

CONTENTS

ABOUT THE AUTHOR ....................................................................................................................................13 ACKNOWLEDGEMENTS.................................................................................................................................................14

INTRODUCTION ...............................................................................................................................................................16 GENERAL MANAGEMENT.............................................................................................................17 PET SUITABILITY ...........................................................................................................................................................................................17 CHOOSING YOUR STOCK ..............................................................................................................................................................17 Selecting an Individual Monitor ............................................................................................................................................18 HANDLING AND HYGIENE............................................................................................................................................................19 TRANSPORTATION ....................................................................................................................................................................................22 Short Journeys.....................................................................................................................................................................................................22 Long Journeys ......................................................................................................................................................................................................23 Timber Boxes..........................................................................................................................................................................................................24 Plastic Containers ...........................................................................................................................................................................................25 PURCHASE AND FREIGHT ETIQUETTE ..................................................................................................................25 Buyers ................................................................................................................................................................................................................................25 Sellers .................................................................................................................................................................................................................................26 LEGAL REQUIREMENTS ....................................................................................................................................................................27 GENERAL SAFETY........................................................................................................................................................................................28 SECURITY....................................................................................................................................................................................................................29 QUARANTINE ......................................................................................................................................................................................................30

HOUSING INDOOR ENCLOSURES ..................................................................................................................................................31

Rack Systems ..........................................................................................................................................................................................................31 Tubs .......................................................................................................................................................................................................................................31 Tanks ....................................................................................................................................................................................................................................32 Pits ...........................................................................................................................................................................................................................................32 Timber Enclosures .........................................................................................................................................................................................33 Glass, Perspex or Plastic Moulded Commercial Terrariums ......................................................33 Mesh Terrariums ...............................................................................................................................................................................................34

OUTDOOR ENCLOSURES ........................................................................................................................................34

Pits ...........................................................................................................................................................................................................................................35 Aviaries ............................................................................................................................................................................................................................36 ENCLOSURE SIZE ..........................................................................................................................................................................................38 Minimum Enclosure Sizes .................................................................................................................................................................38 COMPATIBILITY ...............................................................................................................................................................................................38 page 3

VENTILATION ......................................................................................................................................................................................................40 SUBSTRATE .............................................................................................................................................................................................................40 Sand ......................................................................................................................................................................................................................................40 Soil ...........................................................................................................................................................................................................................................41 Gravel..................................................................................................................................................................................................................................41 Scoria...................................................................................................................................................................................................................................42 Leaf Litter .....................................................................................................................................................................................................................42 Potting Mix ................................................................................................................................................................................................................42 Sphagnum Moss ...............................................................................................................................................................................................42 Peat.........................................................................................................................................................................................................................................42 Bark and Wood Chip...................................................................................................................................................................................43 Wood Shavings ...................................................................................................................................................................................................43 Corn Cob Litter ....................................................................................................................................................................................................43 Walnut Shell Litter .........................................................................................................................................................................................43 Alfalfa/Lucerne Pellets ...........................................................................................................................................................................43 Compressed Timber Pellets ...........................................................................................................................................................43 Compressed Newspaper Pellets.............................................................................................................................................44 Zeolite and Clumping Cat Litter .............................................................................................................................................44 Paper....................................................................................................................................................................................................................................44 Artificial Grass ......................................................................................................................................................................................................44 Indoor/Outdoor Carpet ........................................................................................................................................................................44

HIDE SITES.......................................................................................................................................................................................................44 Vertical Hide Sites ..........................................................................................................................................................................................45 Horizontal Hide Sites ................................................................................................................................................................................46

ENCLOSURE ENRICHMENT ...................................................................................................................................48 Surface Litter ..........................................................................................................................................................................................................48 Branches and Hollows.............................................................................................................................................................................48 Artificial Plants ....................................................................................................................................................................................................48 Dried Plants ..............................................................................................................................................................................................................49 Live Plants ...................................................................................................................................................................................................................50

HEATING ...............................................................................................................................................................................................................51 HEAT CORD OR TAPE ..............................................................................................................................................................................51 HEAT MATS ..............................................................................................................................................................................................................51 HEAT ROCKS ..........................................................................................................................................................................................................52 CERAMIC HEATERS....................................................................................................................................................................................52 GLOBES...........................................................................................................................................................................................................................52 Standard Incandescent Globes................................................................................................................................................52 Reflector Globes ...............................................................................................................................................................................................53 Reptile Lamps .......................................................................................................................................................................................................53 Halogen Bulbs ......................................................................................................................................................................................................53 Infrared Globes ...................................................................................................................................................................................................53 Mercury Vapour Lamps (MVLs) ..............................................................................................................................................54 Metal Halide Bulbs........................................................................................................................................................................................54 page 4

LIGHTING............................................................................................................................................................................................................56 THE SCIENCE OF LIGHTING .......................................................................................................................................................56 Visible Light..............................................................................................................................................................................................................56 Infrared ............................................................................................................................................................................................................................56 Ultraviolet A (UV-A) .....................................................................................................................................................................................56 Ultraviolet B (UV-B) ......................................................................................................................................................................................56 Ultraviolet C (UV-C)......................................................................................................................................................................................59 LIGHTING OPTIONS .................................................................................................................................................................................59 UV-B Emitting Fluorescent Tubes.........................................................................................................................................60 Black Lights...............................................................................................................................................................................................................60 Compact UV-B Emitting Lamps ...............................................................................................................................................61 Mercury Vapour Lamps .........................................................................................................................................................................61 ‘Modified’ Halogen (Quartz or Dichroic Halogens) Bulbs ............................................................63 Metal Halide Lamps ....................................................................................................................................................................................63

THERMOSTATS ...................................................................................................................................................................................63

Probe Thermostats .......................................................................................................................................................................................64 On/Off Thermostats ....................................................................................................................................................................................64 Dimming Thermostats............................................................................................................................................................................65 Pulse Proportional Thermostats ............................................................................................................................................65

HUMIDITY .......................................................................................................................................................................................................65

FEEDING METHODS AND NUTRITION INVERTEBRATE FOOD ITEMS......................................................................................................................67

Crickets—Acheta domestica .................................................................................................................................................................67 Cockroaches ............................................................................................................................................................................................................68 Mealworms—Tenebrio molitor .........................................................................................................................................................68 King Mealworms or Superworms—Zophobas morio .................................................................................69 Maggots/Flies/Pupae—Musca vetutissima ..................................................................................................................69 Slaters.................................................................................................................................................................................................................................70 Silkworms—Bombyx mori and other caterpillars ............................................................................................70 Termites ..........................................................................................................................................................................................................................70 Earthworms—Lumbricus terrestrius ...........................................................................................................................................70 Locusts—Chortoicetes terminifera .................................................................................................................................................70 Spiders ..............................................................................................................................................................................................................................71 Fruit Flies—Drosophila species .....................................................................................................................................................71 Snails—Helix aspersa and other species .........................................................................................................................71 Crustacea—Freshwater Crayfish, Prawns and Shrimp......................................................................71 Waxworms—Galleria mellonella ....................................................................................................................................................72 Wild Fodder ..............................................................................................................................................................................................................73 Nutritional Data Averages for Invertebrate Diets.....................................................................................73

VERTEBRATE FOOD ITEMS ................................................................................................................................75

Rats and Mice ........................................................................................................................................................................................................75 Chicks and Small Birds ...........................................................................................................................................................................76 page 5

Guinea Pigs ...............................................................................................................................................................................................................76 Fish ..........................................................................................................................................................................................................................................76 Reptiles ............................................................................................................................................................................................................................76 Nutritional Data Averages for Vertebrate Diets ...........................................................................................77

ARTIFICIAL DIETS.......................................................................................................................................................................78 CARNIVOROUS/INSECTIVOROUS DIETS ...........................................................................................................78 San Diego Zoo Diet ......................................................................................................................................................................................78

CULTURING INSECT FOOD ITEMS ..................................................................................................79

Crickets—Acheta domestica .................................................................................................................................................................79 Speckled Feeder Roaches—Nauphoeta cinerea ..................................................................................................82 Locusts—Chortoicetes terminifera .................................................................................................................................................82 Slaters.................................................................................................................................................................................................................................83

DIETARY SUPPLEMENTS .........................................................................................................................................84 CALCIUM ......................................................................................................................................................................................................................84 Gut Loading .............................................................................................................................................................................................................84 Dusting.............................................................................................................................................................................................................................85 PROTEIN........................................................................................................................................................................................................................86

FEEDING FACILITIES ...........................................................................................................................................................86 FEEDING PROBLEMS .........................................................................................................................................................88 TREATMENT ..........................................................................................................................................................................................................89 Assist Feeding .....................................................................................................................................................................................................89 Force Feeding........................................................................................................................................................................................................89 Tube Feeding .........................................................................................................................................................................................................90

BREEDING VISUAL SEXING..................................................................................................................................................................................91

Colour.................................................................................................................................................................................................................................91 Size ..........................................................................................................................................................................................................................................92 Femoral and Preanal Pores .............................................................................................................................................................92 Hemipenal Bulges..........................................................................................................................................................................................93 Paracloacal Spur Structures ..........................................................................................................................................................93 OTHER SEXING TECHNIQUES .................................................................................................................................................94 Hemipenal Probing .....................................................................................................................................................................................94 Hemipenal Popping....................................................................................................................................................................................94 Hemipenal Transillumination .....................................................................................................................................................95 Hemipenal Observation ......................................................................................................................................................................98 Hemipenal Plug Observation .....................................................................................................................................................99 Hemipenal Palpation ................................................................................................................................................................................99 Ultrasound .................................................................................................................................................................................................................99 Radiography—X-ray Examination..................................................................................................................................100

BREEDING AGE.................................................................................................................................................................................102 page 6

COURTSHIP ...............................................................................................................................................................................................102 MATING ...............................................................................................................................................................................................................102 STRATEGIES TO ENHANCE BREEDING SUCCESS ......................................102 COOLING ................................................................................................................................................................................................................102 SEPARATION .....................................................................................................................................................................................................104

REPRODUCTION...........................................................................................................................................................................104 REPRODUCTIVE STRATEGIES.............................................................................................................................................104 EGG TYPE ................................................................................................................................................................................................................105 CLUTCH SIZE .....................................................................................................................................................................................................105 BREEDING FREQUENCY ...............................................................................................................................................................105 REPTILIAN REPRODUCTIVE SENILITY .............................................................................................................105 GRAVIDITY ...........................................................................................................................................................................................................106 CARING FOR BREEDING FEMALE MONITORS ......................................................................................107

NEST FACILITIES ...........................................................................................................................................................................108 ARBOREAL SPECIES.............................................................................................................................................................................109 TERRESTRIAL SPECIES....................................................................................................................................................................109

EGG LAYING .............................................................................................................................................................................................111 EGG MANAGEMENT ............................................................................................................................................................................111 Collecting and Handling .................................................................................................................................................................111 Determining Egg Viability ............................................................................................................................................................113

ARTIFICIAL INCUBATION.......................................................................................................................................116 INCUBATION FACILITIES .............................................................................................................................................................116 CONTAINERS.....................................................................................................................................................................................................116 HEATING ...................................................................................................................................................................................................................117 TEMPERATURE CONTROL .........................................................................................................................................................119 INCUBATION MEDIUM ....................................................................................................................................................................119 Vermiculite.............................................................................................................................................................................................................119 Perlite..............................................................................................................................................................................................................................119 Sphagnum Moss ...........................................................................................................................................................................................120 True Peat Moss ................................................................................................................................................................................................120 Coir Peat Moss ................................................................................................................................................................................................120 No Substrate .......................................................................................................................................................................................................120 INCUBATION REGIMES ...................................................................................................................................................................121 TEMPERATURE DEPENDENT SEX DETERMINATION.................................................................121

NATURAL INCUBATION..............................................................................................................................................122 HATCHLING CARE .....................................................................................................................................................................122 FEEDING ...................................................................................................................................................................................................................122 Feeding Frequency ..................................................................................................................................................................................123 Supplementation ........................................................................................................................................................................................123 page 7

LIGHTING ................................................................................................................................................................................................................123 HOUSING.................................................................................................................................................................................................................123 HEATING ...................................................................................................................................................................................................................123 COMPATIBILITY ...........................................................................................................................................................................................123

COMMON DISEASES AND DISORDERS DISCLAIMER............................................................................................................................................................................................124 NUTRITIONAL DISORDERS ...............................................................................................................................125 OBESITY ....................................................................................................................................................................................................................125 METABOLIC BONE DISEASE (CALCIUM/VITAMIN D3 DEFICIENCY)..............125 Early Onset Metabolic Bone Disease ..........................................................................................................................125 Late Onset Metabolic Bone Disease ............................................................................................................................126 Delayed Metabolic Bone Disease.....................................................................................................................................126 Reproductive Metabolic Bone Disease...................................................................................................................127 GUT IMPACTION ........................................................................................................................................................................................127

PARASITIC DISORDERS ..............................................................................................................................................129 INTERNAL PARASITES .....................................................................................................................................................................129 EXTERNAL PARASITES....................................................................................................................................................................130

SKIN DISORDERS ........................................................................................................................................................................131 DYSECDYSIS.......................................................................................................................................................................................................131 SCALE ROT ............................................................................................................................................................................................................131

NAIL, TOE AND LIMB DISORDERS...................................................................................................132 EYE DISORDERS.............................................................................................................................................................................132 EYE TRAUMA.....................................................................................................................................................................................................132 PHOTO-KERATOCONJUNCTIVITIS ............................................................................................................................133 PRIMARY BACTERIAL EYE INFECTIONS ..........................................................................................................133

RESPIRATORY DISORDERS................................................................................................................................133 BACTERIAL PNEUMONIA ...........................................................................................................................................................134 VITAMIN A DEFICIENCY ...............................................................................................................................................................134 HUMIDITY RELATED PROBLEMS..................................................................................................................................134 PARASITIC PNEUMONIA ............................................................................................................................................................134

TRAUMA............................................................................................................................................................................................................135 BITE INJURIES .................................................................................................................................................................................................135 THERMAL BURNS .....................................................................................................................................................................................135

REPRODUCTIVE DISORDERS.......................................................................................................................136 PRE-OVULATORY AND POST-OVULATORY STASIS (EGG BINDING OR DYSTOCIA) ..........................................................................................................................................136 page 8

UTERINE INFECTION ..........................................................................................................................................................................138 HEMIPENAL INJURIES AND INFECTION..........................................................................................................139 CONGENITAL DEFECTS ..................................................................................................................................................................140

NASAL AND ORAL DISORDERS .............................................................................................................142 NASAL ABRASIONS—NOSE RUBS ............................................................................................................................142 JAW DISEASE/PERIODONTITIS/STOMATITIS.........................................................................................142

ADMINISTRATION OF MEDICATIONS ...................................................................................143 SUBCUTANEOUS OR INTRAMUSCULAR INJECTIONS ............................................................143 LIQUID ORAL MEDICATION ...................................................................................................................................................144 ORAL TABLET MEDICATION ..................................................................................................................................................146

MAKING THE MOST OF YOUR REPTILE VETERINARIAN.........146

SPECIES

LARGE TERRESTRIAL AND ARBOREAL MONITORS PRONUNCIATION .....................................................................................................................................................................................149

DESCRIPTION..............................................................................................................................................................................150

ADULTS, JUVENILES, SEXING, SUBSPECIES ............................................................................................150

IN THE WILD .....................................................................................................................................................................................158

DISTRIBUTION AND HABITAT ...........................................................................................................................................158

IN CAPTIVITY ...............................................................................................................................................................................160

STATUS ........................................................................................................................................................................................................................160

HOUSING .......................................................................................................................................................................................................160 INDOOR ENCLOSURES....................................................................................................................................................................160 Summary...................................................................................................................................................................................................................163 OUTDOOR ENCLOSURES ............................................................................................................................................................163 COMPATIBILITY ...........................................................................................................................................................................................164

FEEDING ..........................................................................................................................................................................................................165 BREEDING....................................................................................................................................................................................................166 INCUBATION AND HATCHLING DEVELOPMENT..............................................................................169 BREEDING RECORDS FOR LARGE TERRESTRIAL AND ARBOREAL MONITOR SPECIES ......................................................................................................................................170 HYBRIDISATION AND COLOUR VARIANTS .................................................................................................170 LONGEVITY .........................................................................................................................................................................................................172 ACKNOWLEDGEMENTS ................................................................................................................................................................172 page 9

ROCK MONITORS PRONUNCIATION .....................................................................................................................................................................................173

DESCRIPTION..............................................................................................................................................................................173

ADULTS, JUVENILES, SEXING, SUBSPECIES ............................................................................................173

IN THE WILD .....................................................................................................................................................................................177

DISTRIBUTION AND HABITAT ...........................................................................................................................................177

IN CAPTIVITY ...............................................................................................................................................................................178

STATUS ........................................................................................................................................................................................................................178

HOUSING .......................................................................................................................................................................................................178 INDOOR ENCLOSURES....................................................................................................................................................................178 Summary...................................................................................................................................................................................................................180 OUTDOOR ENCLOSURES ............................................................................................................................................................180 COMPATIBILITY ...........................................................................................................................................................................................181

FEEDING ..........................................................................................................................................................................................................181 BREEDING....................................................................................................................................................................................................182 INCUBATION AND HATCHLING DEVELOPMENT..............................................................................185 BREEDING RECORDS FOR ROCK MONITOR SPECIES .............................................................186 HYBRIDISATION AND COLOUR VARIANTS .................................................................................................186 LONGEVITY .........................................................................................................................................................................................................186 ACKNOWLEDGEMENTS ................................................................................................................................................................186

SMALL TERRESTRIAL MONITORS PRONUNCIATION .....................................................................................................................................................................................187

DESCRIPTION..............................................................................................................................................................................187

ADULTS, JUVENILES, SEXING, SUBSPECIES ............................................................................................187

IN THE WILD .....................................................................................................................................................................................196

DISTRIBUTION AND HABITAT ...........................................................................................................................................196

IN CAPTIVITY ...............................................................................................................................................................................198

STATUS ........................................................................................................................................................................................................................198

HOUSING .......................................................................................................................................................................................................198

INDOOR ENCLOSURES.................................................................................................................................................................. 198 Summary...................................................................................................................................................................................................................200 OUTDOOR ENCLOSURES ............................................................................................................................................................200 COMPATIBILITY ...........................................................................................................................................................................................201

FEEDING ..........................................................................................................................................................................................................201 BREEDING....................................................................................................................................................................................................202

INCUBATION AND HATCHLING DEVELOPMENT..............................................................................205 page 10

BREEDING RECORDS FOR SMALL TERRESTRIAL MONITOR SPECIES .......205 HYBRIDISATION AND COLOUR VARIANTS .................................................................................................206 LONGEVITY .........................................................................................................................................................................................................206 ACKNOWLEDGEMENTS ................................................................................................................................................................206

SMALL TO MEDIUM ARBOREAL MONITORS PRONUNCIATION .....................................................................................................................................................................................207

DESCRIPTION..............................................................................................................................................................................207

ADULTS, JUVENILES, SEXING, SUBSPECIES ............................................................................................207

IN THE WILD .....................................................................................................................................................................................221

DISTRIBUTION AND HABITAT ...........................................................................................................................................221

IN CAPTIVITY ...............................................................................................................................................................................224

STATUS ........................................................................................................................................................................................................................224

HOUSING .......................................................................................................................................................................................................225 INDOOR ENCLOSURES....................................................................................................................................................................225 Summary...................................................................................................................................................................................................................226 OUTDOOR ENCLOSURES ............................................................................................................................................................227 COMPATIBILITY ...........................................................................................................................................................................................227

FEEDING ..........................................................................................................................................................................................................228 BREEDING....................................................................................................................................................................................................229 INCUBATION AND HATCHLING DEVELOPMENT..............................................................................230 BREEDING RECORDS FOR SMALL TO MEDIUM ARBOREAL MONITOR SPECIES ...............................................................................................................................................................................231 HYBRIDISATION AND COLOUR VARIANTS .................................................................................................232 LONGEVITY .........................................................................................................................................................................................................232 ACKNOWLEDGEMENTS ................................................................................................................................................................232

WATER MONITORS PRONUNCIATION .....................................................................................................................................................................................233

DESCRIPTION..............................................................................................................................................................................233

ADULTS, JUVENILES, SEXING, SUBSPECIES ............................................................................................233

IN THE WILD .....................................................................................................................................................................................241

DISTRIBUTION AND HABITAT ...........................................................................................................................................241

IN CAPTIVITY ...............................................................................................................................................................................244

STATUS ........................................................................................................................................................................................................................244

HOUSING .......................................................................................................................................................................................................244 INDOOR ENCLOSURES....................................................................................................................................................................244 Summary...................................................................................................................................................................................................................247 page 11

OUTDOOR ENCLOSURES ............................................................................................................................................................247 COMPATIBILITY ...........................................................................................................................................................................................248

FEEDING ..........................................................................................................................................................................................................248 BREEDING....................................................................................................................................................................................................249 INCUBATION AND HATCHLING DEVELOPMENT..............................................................................251 BREEDING RECORDS FOR WATER MONITOR SPECIES .........................................................252 HYBRIDISATION AND COLOUR VARIANTS .................................................................................................253 LONGEVITY .........................................................................................................................................................................................................253 ACKNOWLEDGEMENTS ................................................................................................................................................................253

AUSTRALIAN HERPETOLOGICAL SOCIETIES AND USEFUL WEBSITES HERPETOLOGICAL SOCIETIES ..........................................................................................................................................254 OTHER USEFUL WEBSITES.......................................................................................................................................................255

BIBLIOGRAPHY PRINTED LITERATURE......................................................................................................................................................................255 ONLINE RESOURCES ..........................................................................................................................................................................258

S EIPPER

GLOSSARY .....................................................................................................................................................................................259

Varanus brevicauda

page 12

C GUEST

Timber Enclosures These python-style enclosures feature five solid sides and a glass or mesh front. Timber enclosures are secure, accessible, aesthetically pleasing, easy to supply light and heat to and may be purchased commercially or be homemade.

They are suitable for accommodating terrestrial and arboreal species, depending on furniture placement.

Their suitability as arboreal enclosures can be improved by decorating the rear and side walls with mock rock or by firmly attached furnishings.

The main disadvantages of timber enclosures are that they are expensive, difficult to ventilate, prone to overheating, heavy and are generally only suitable for dry furnishings—sealed timber and melamine will eventually succumb to water damage.

Glass, Perspex or Plastic Moulded Commercial Terrariums

Melamine enclosures with sliding glass fronts

Commercial glass terrariums are ideal for small terrestrial species

D BROWN

D BROWN

Increasing in popularity and availability, these enclosures feature three to four solid sides and one to two mesh sides—or two sides made of half mesh—and a glass front door.

Glass terrariums are secure—although some small arboreal monitors can secrete themselves into very narrow gaps, few adults lizards have narrow enough heads to escape from standard glass doors or narrow ventilation gaps. They are also durable, available in standard sizes allowing for standard shelving, and are easily made aesthetically appealing—some include mock rock backgrounds as a standard fitting.

Moulded plastic terrariums with modified wire fronts are used in the author’s collection for small arboreal species

page 33

D BROWN

D BROWN

Sunlight and moonlight replicating reptile lamps

D BROWN

D BROWN

can be difficult. Use electrical mounting blocks secured by a silicone sealant suitable for aquarium manufacture to the glass enclosure walls. This supports the actual light fitting and accommodates the wiring. Improve the Reptile infrared lamp stability of these attached mounting blocks by marking the base of the mounting block with several small holes or scratches to give the silicone something to grip to. These mounting blocks then become the base upon which you attach a lamp fitting. I recommend using adjustable light sockets that can be directed downwards at a 45 degree angle. Alternatively, a simple angle bracket constructed from galvanised steel or aluminium can be stuck to the glass using silicone or double-sided tape. This acts as a base upon which a ‘clamp lamp’ can be attached. IKEATM sells a wonderful range of ‘clamp lamps’.

• Position heat lamps towards one end of the enclosure to allow a heat gradient to be established and to encourage air flow from one area to another.

• Use in line dimming units such as the IKEA DimmaTM in small enclosures to regulate maximum temperatures and avoid overheating.

This commercial IKEA™ ‘clamp lamp’ is ideal for small hatchlings

Use a mounting block to attach a lamp to a glass surface

page 55

VERTEBRATE FOOD ITEMS Virtually all reptile families include at least one species that feeds on vertebrate food items such as rats, mice, chicks, quail, guinea pigs, small birds, fish and other lizards.

Monitors will accept almost any type of vertebrate prey, consuming almost anything physically possible. Most will consume mice, rats, chicks, guinea pigs, small birds—such as sparrows, quail and finches—and fish. Few species seem to be particularly fussy. Small hatchlings will accept chopped pinkie mice and small fish.

Avoid feeding large items or large meals to large specimens. Although they may be able to physically eat the meal, many may regurgitate it afterwards. Feeding to 80% of swallowing capacity is more acceptable.

Vertebrate food items have various features to be aware of.

Rats and Mice

J SEIJDEL

D BROWN

These vertebrate food items can be fed to a range of lizard species at every life stage. Generally, smaller life stages of mammalian prey such as pinkies, fuzzies and weaners are more nutritionally suitable than larger life stages, which often carry higher levels of fat and lower levels of protein.

A lizard’s ability to digest rats and mice improves when multiple, small items are fed— rather than single, large items with a greater surface area to digest. Some keepers believe multiple, small items are less Mouse sizes (left to right)—large adult, regular adult, weaner, hopper, nutritional as they may possess fuzzie and pinkie more indigestible hair than a large item—studies have disproved this theory.

Mice and rats should be fed a quality commercial diet designed for laboratory rats and mice. Cutting corners will alter their nutritional value and usually increase their fat content.

Feeding pinkie mice and rats that have a full stomach of milk is equivalent to gut loading with calcium, due to the high calcium component of the mother mouse’s milk. This increases the Varanus indicus feeding on a rat calcium to phosphorus ratio to the equivalent of an older juvenile with more mineralised bones. page 75

S MACDONALD

BREEDING VISUAL SEXING

G SCHMIDA

This male Varanus ‘kuranda’ displays brighter ocelli and a bright yellow throat

The correct identification of gender is the first step towards breeding success.

For many species, this process is simple—for others it requires educated guesswork.

There are various methods of sexing lizards, which range in complexity and reliability. Visual sexing is one of the most common methods and involves This female Varanus ‘kuranda’ displays duller body and the examination of a lizard’s secondary throat colour sexual characteristics including colour, size, pore structures, hemipenal bulges and paracloacal spur structures.

Following is an outline of each method. For more specific details of distinguishing features in each species refer to the individual species chapters.

Colour Many lizard species display considerable sexual dimorphism with regard to colour patterns in particular. Colour differences are noted among some species of monitors but are limited primarily to differences in overall brightness or throat coloration. page 91

D BROWN

D BROWN

‘Pink side up’—the pink side represents the embryonic side. This should be placed upwards in the incubation container

The yellow side of the egg represents the yolk side.

This should be placed downwards in the incubation container

Determining Egg Viability

D BROWN

D BROWN

There is little benefit incubating eggs that have no likelihood of hatching. Therefore, it is important to be able to identify which eggs are viable—of adequate quality and fertility. Viability should be assessed pre-incubation at the time of collection, and post-incubation for 10−20 days following incubation.

Pre-incubation indicators of non-viable eggs are— Yellowish coloured eggs Good quality eggs are generally a clean, white colour.

Sunken eggs Particularly if other eggs in the clutch appear normal.

Soft and squishy eggs Eggs that indent easily may indicate drying or non-viability.

Firmness Viable eggs are generally plump and slightly compressible like a well inflated balloon. Eggs that are hard are often referred to as ‘slugs’ and are infertile, non-viable eggs.

Adherence of substrate While it may be quite normal for the eggs of some species to have substrate stuck to the eggs, it should be consistent throughout the whole clutch.

Different sized eggs in one clutch Significant differences in the size of eggs within a single clutch may indicate some eggs—generally the smaller A freshly laid, healthy, plump, clean ones—are non-viable.

Varanus gilleni egg being candled— Sorting good eggs from bad is generally simple. However, note the germinal ring if there is any doubt, suspect eggs should be incubated anyway. Equally, not every egg that appears viable will stay that way. Eggs that appear healthy initially may still fail if the embryo does not develop or dies. Most non-viable eggs that initially appear healthy will fail the first 7−14 days after incubation.

Infertile ‘slugs’ from a Varanus storri

page 113

D BROWN

Treatment can involve the use of medication. However, this medication should be targeted precisely at the parasite involved, which can only be determined through the analysis of faecal samples. Medication should be targeted in this way rather than by ‘shotgun’ medication.

There are many commercial antiparasitic products available, but few are designed for reptiles.

Each lizard group may vary in its reactions to medication—a safe drug in a dragon may potentially be toxic to a monitor and vice versa. Therefore, it is unsafe for me to record dose rates here.

Consult your reptile veterinarian for their preferred medication regime.

Treatment may also require de-stocking and decontamination to prevent reinfection— particularly with coccidial and pinworm infections.

ANON

Multiple ticks on a Varanus giganteus

EXTERNAL PARASITES Ticks and mites are the two main external parasites occasionally found on lizards. Ticks are generally only found on specimens housed outdoors, although it is possible that tick larvae may be transported on leaf litter into an indoor enclosure. These large, blood-sucking parasites are more unsightly than dangerous. However, due to problems associated with the toxicity of acaricidal drugs, it is best to remove them as soon as they are observed. Simply grip the tick between your fingers, or with forceps, and employ a twisting and pulling motion to remove them.

Mites which cause clinical disease are a limited problem to lizards. Although lizards may be inhabited by mite species, they are rarely infected by the snake mite Ophionyssus, although this has been observed on rare occasion on pygopods— particularly Lialis burtonis—and on larger skinks such as Tiliqua species. This could be because these lizards have a similar scale pattern to snakes compared to a monitor’s scales.

Treatment methods include smothering the mites with spray-on kitchen oils. Alternatively, chemical treatments such as ivermectin-based sprays may be used on dragons, skinks and monitors—avoid the head and wash the spray off after 15 minutes.

Consult your reptile veterinarian for appropriate dose rates.

Non-pathogenic mites commonly affect lizards.

These small, red mites target eye sockets, armpits and groin areas and occur when lizards are housed outdoors or if an enclosure’s furnishings are sourced from where the mites naturally occur.

Non-pathogenic red mites in the groin area of Varanus ‘scalaris’

page 130

Hatchlings are a brighter version of the adult, particularly Kimberley Rock Monitors V. glauerti.

They are generally 25−40% of adult size. Adult colouration develops at 3−4 months of age and individuals reach full adult colouration at 50−70% of adult SVL.

K PATANANT

JUVENILES

SEXING

ANON

K PATANANT

B VAN ASTEN

Rock monitors should be sexed using a combination of methods.

Visually, males are generally larger than females of the same age and have a broader, more robust head and body.

The male spur clusters differ from that of the female. They are similar to that of the Black-headed Monitor Varanus tristis and are located at the base of the tail above the vent. The clusters comprise Varanus glauerti hatchlings approximately 10−12 roughly oval-shaped, conical scales that are smaller at the perimeter and larger in the centre, forming a small, spiky mound. In males, the largest scales are 2−4 times the size of the adjacent scales, whereas females’ largest scales are only 1−1.5 times the size of the adjacent body scales. Males also have a greater number of larger scales per cluster than females.

The spur scales of the Kimberley Rock Monitor Varanus pilbarensis hatchling V. glauerti are often chocolate brown or grey and creamy white in colouration. In the Pilbara Rock Monitor V. pilbarensis they are flatter, fan-shaped and the individual spur components are larger and more numerous in males than in females.

When sexing using paracloacal spurs, be aware that spur clusters are larger during the breeding season due to an increase in the thickness of the keratin layer over the spur scales at this time.

Radiography of the tail base of adult males will reveal the presence of calcifications of the support structures of the hemipenes, referred to as ossified hemibacula. These structures are absent in adult Leucistic form (left) and Normal V. kingorum females, but present among males of all species hatchlings in this group. It is not known at what average age the hemipenal support structures develop calcification. I have not personally had the opportunity to examine radiographs of any of these species, but I have observed calcifications in most male monitors at proportions equivalent to 60−70% of adult SVL—this should be considered the smallest size for this technique to be considered reliable. The presence of ossifications from this age onwards indicates a male, however page 175

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Varanus acanthurus

SMALL TERRESTRIAL MONITORS

The small terrestrial monitor group comprises six species as follows— Ridge-tailed Monitor or Spiny-tailed Monitor Varanus acanthurus Black Spotted Spiny-tailed Monitor, White’s Monitor or Lemon-throated Monitor Varanus baritji Storr’s Monitor Varanus storri Northern Blunt Spined Monitor or Northern Ridge-tailed Monitor Varanus primordius Short-tailed Pygmy Monitor or Short-tailed Monitor Varanus brevicauda Pygmy Desert Monitor or Rusty Desert Monitor Varanus eremius

PRONUNCIATION Following are the accepted pronunciations of the six small terrestrial monitor species— Varanus acanthurus Varr-ann-us ack-an-thoo-rus Varanus baritji Varr-ann-us bah-rit-jee Varanus storri Varr-ann-us store-ee Varanus primordius Varr-ann-us pry-more-dee-us Varanus brevicauda Varr-ann-us brev-ee-cord-ah Varanus eremius Varr-ann-us er-em-ee-us

DESCRIPTION ADULTS The majority of the small terrestrial monitors fall into a group known as spiny-tailed monitors— so called due to the heavy scalation on their tails, which are robust, round in cross section and display sharp backward pointing spines. They have a sharp, pointed snout, long bodies and tails varying from 80−200% of their body length. page 187

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Suitable substrate is sand at a depth of 100−150mm to allow for digging although species including the Pygmy Desert Monitor V. eremius and the Short-tailed Pygmy Monitor V. brevicauda will appreciate substrate to a depth of at approximately 250mm.

‘Monitor stacks’ made from separated layers of plywood or tiles, mimic layers of exfoliating rocks and provide shelter and basking sites. These layers should be separated using 20−25mm timber slats firmly anchored to the plywood so they don’t collapse. A terracotta or slate tile placed on the top level will reduce the fire risk associated with heated timber. The basking lamp should be directed on to the top of the vertical stacks to create a vertical heat gradient. Some keepers also place a heat pad at the bottom of the stack.

Alternatively, the enclosure may be decorated with rock slabs, solid branches, terracotta tiles or roof tiles. All structures must be placed directly onto the enclosure floor to prevent collapse— monitors regularly dig at the base of structures, undermining their stability. Vegetation is not recommended as it is usually destroyed by monitor digging behaviour.

Species including the Pygmy Desert Monitor V. eremius and the Short-tailed Pygmy Monitor V. brevicauda may be provided with a flat tile laid directly on the sand surface under the heat lamp to allow for burrowing behaviour at the same time as subsoil and surface basking. Glue short timber legs onto these tiles to ensure they always remain above the enclosure floor even if the sand is dug out underneath.

Alternatively, place the tile or timber stack on top of a wide flat tray, such as a cat litter tray, filled to the top with moist sand. This will allow for burrowing behaviour, surface and subsoil basking and provide a potential nesting site with a heat gradient. It also allows much more control over soil moisture levels. Access to this area can be provided by a single hole in the surface tile.

Small terrestrial monitors originate from hot environments and require high environmental temperatures. A basking temperature of 40oC−70oC with a heat gradient of 28oC−35oC in the remainder of the enclosure is ideal. Although these temperatures might seem extreme, these small monitors thrive on it. Cooler temperatures will also be present within enclosure burrows.

Heat should be provided for at least 14 hours daily during summer and for 4–6 hours daily during winter. Heating time can be gradually reduced from mid-autumn by 30–60 minutes each week. This heating regimen allows the occupants to bask if they need and spend most of the day in ambient winter conditions. I believe this is important for small species with high metabolic rates—less post cooling problems are noted than if no heat is provided at all.

Alternatively, some keepers provide 8–10 hours of heating daily over the entire winter period with a 10oC drop in the heat gradient and basking temperature across the entire enclosure.

In environments similar to their natural temperature range, heating may be turned off in winter and visible light utilised to mimic the photoperiod.

Components of a suitable enclosure

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