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Monitor Lizard Care, Natural History and Behavior – An Overview

Nile Monitor I’ve had the good fortune of caring for 15-20 monitor species during my zoo career. From the diminutive Storr’s to the massive Water, Lace, Crocodile and Komodo Monitors, all have instilled in me the feeling that they were, somehow, “more complicated” than other reptiles. Indeed, recent studies have confirmed that they are, among lizards, highly advanced.  While some are too large for the average household, several moderately-sized and even dwarf varieties are being bred by hobbyists, and all make fascinating and responsive captives.

The following information can be applied to the care of Savannah, Black Tree, Nile, Merten’s and most other monitors.  However, details vary; please post below for information on individual species, and be sure to add your own thoughts and observations on monitor lizard care.

Natural History

Seventy-three monitor species (Family Varanidae) range across Asia, Africa and Australia. Nile Monitors (Varanus niloticus), introduced to south Florida, are a major environmental concern there.  Lace Monitors (V. varius) and other large speciesare usually the dominant predators in their habitats.  While most dwell in warm regions, Desert Monitor (V. griseus) populations in Kazakhstan are adapted to Vermont-type winters.  Read More »

Hermit Crab Pets: The Coconut Crab & Other Species

Coconut CrabPeople are often surprised to learn that Land or Terrestrial Hermit Crabs engage in complex social behaviors, are capable of communicating via “chirps” and, with proper care, may live for over 20 years.  I’ve had the pleasure of working with them at home, in zoos and the wild, and have even kept the massive, awe-inspiring Coconut Crab.  Please read on to learn about their care and natural history, and be sure to post your own thoughts and experiences.

Hermit Crab Natural History

The Purple-Pincher or Caribbean Hermit Crab (Coenobita clypeatus) is the most common pet trade species.  It ranges throughout the Caribbean, reaching as far north as Florida and Bermuda.

Some populations live at altitudes of over 3,000 feet, but females return to the sea, usually in one massive migration, to spawn. The larvae, or zoea, float about with plankton for 2 months, after which they take up life on land. Read More »

American Box Turtles as Pets – Care and Natural History

Male Eastern Box TurtleThe beautifully-patterned American Box Turtles (Terrapene spp.) are very popular among reptile enthusiasts worldwide. They are extremely responsive, intelligent, calm, and may live for 60-100 years…what more could a turtle fan want!  Unfortunately, there are many misconceptions concerning their care.  The following information will enable you to meet their needs…please post any specific questions you may have.

Note: Box Turtle populations have declined drastically. In addition to habitat loss and road-kill, many were exported to foreign pet markets when European tortoises were protected by law.  Please purchase only captive-bred animals.

Natural History

Four Box Turtle species the Eastern, Spotted, Ornate and Coahuilan – range from southern Canada through most of the USA and into Mexico.  Ten uniquely-colored subspecies, including the Florida, Gulf Coast and Yucatan Box Turtles, are also recognized.

Box Turtles frequent woodlands, marshes, fields, agricultural land, and many other habitats.  Some, such as the Eastern Box Turtle (T. carolina), are largely terrestrial, while Three-Toed Box Turtles (T. carolina triunguis) and others split their time between land and shallow water.  The Coahuilan Box Turtle (T. coahuila), the group’s only truly aquatic member, is found only in Mexico’s Cuatro Cienegas Basin.  Several of my colleagues at the Bronx Zoo studied this species in the wild, and I had the good fortune to work with a breeding group for many years; please look for my future article on this most unique turtle.

Although certain other turtles posses shell hinges that allow the plastron (lower shell) to be drawn up (“like a box”), in no group is this ability so well developed as the American Box Turtles (please see photo). Read More »

Malayan and Kuhl’s Flying Geckos – Breeding and Care

Ptychozoon kuhliLike most lizard enthusiasts, I was mesmerized by Flying Geckos at first glance. Early on, both Malayan and Kuhl’s Flying Geckos (Ptychozoon lionotum and P. Kuhli) were rare in the trade, but by the early 1980’s I found them readily available and integrated both into a Southeast Asian exhibit I maintained at the Bronx Zoo. I had some breeding success, but today’s stock remains largely wild caught.  Because they are both inexpensive and bizarre, Flying Geckos are often purchased by relatively inexperienced keepers. But while they can be hardy, prolific breeders, Flying Gecko ownership requires some forethought; hopefully the following information will prepare you.

Description

The 7 Flying Geckos in the genus Ptychozoon are among the most unique of the world’s 900+ gecko species.  Both the Malayan and Kuhl’s reach 6-8 inches in length and are distinguished by skin folds (along the head, flanks and toes) that enable them to glide through the air. A heavily-serrated tail assists in breaking up their outline. In overall appearance, I can best describe them as “amazingly bark-like”.

Their color varies through a wide range of tans, grays and browns, and the skin is marked with an array of blotches and stripes.  Malayan and Kuhl’s Flying Geckos are difficult to differentiate by eye; the Kuhl’s tongue is often tipped in black, but I cannot say whether this always holds true.

Range and Habitat

The Malayan Flying Gecko inhabits Myanmar, Thailand, India, Malaysia and neighboring islands. The range of Kuhl’s Flying Gecko extends from southern Thailand through Java, Sumatra, Malaysia, Borneo and Sulawesi, and overlaps that of its cousin extensively.  Whether or not they hybridize, or utilize different niches within the same range, has not been researched. Other geckos are, however, known to partition habitats in species-rich areas; this article describes an interesting study carried out on Borneo.

Flying Geckos favor rainforests and other humid, densely-foliated habitats. However, they have colonized farms and human habitations, and it is from such areas that most are collected.

Captive Care

Malayan and Kuhl’s Flying Geckos may be kept and bred under similar conditions. As most in the trade are wild-caught, stress, mites and internal parasites are a major concern. As concerns medication, I’ve found them to be quite delicate; be sure that you use a well-experienced veterinarian to examine all new arrivals.

The Terrarium

Although wild-caught females may initially produce eggs, sustained captive breeding is only possible if the appropriate environment and diet is provided.  A spacious terrarium – a 20-30 gallon tank for a trio – is essential.  “Tall” style aquariums are ideal.  Flying Geckos spend most of their time on tree trunks, where their camouflage may be used to great advantage, and will be stressed if forced to use other resting sites.  Corkbark or native tree bark must be available, and the cage should be densely-planted (live plants are best).  Flying Geckos will not thrive in bare enclosures.

Temperature, Humidity and Light

Humidity should be maintained at 75-80% for most of the year (see “Breeding”), with a temperature gradient of 75-85 F.  Nighttime temperatures can dip to 70 F. A mix of sphagnum moss and a forest bedding, serves well as a substrate.

Flying GeckoAlthough Flying Geckos are nocturnal, wild individuals often spend their days in open situations, on tree trunks, and may therefore be exposed to UVB.  Low doses of UVB, as provided by a ZooMed 2.0 bulb, are likely beneficial.  Overly-bright environments should be avoided, so choose plants that do well in low light (pothos, snake and cast iron plants).  Incandescent heat bulbs  can be used to maintain temperatures; red/black night bulbs (which will assist in nighttime observations) or ceramic heater-emitters can be used after dark.

Diet

Flying Geckos specialize in hunting flying and arboreal insects, and will not fare well on crickets alone.  Housefly cultures, silkworms, roaches, moths and other insects are essential to their well-being.  The comments in this article on Red-Eyed Treefrog Diets are largely applicable; please write in if you have any questions on this critical aspect of husbandry.

Breeding

Mature males may be distinguished from females by their pre-anal pores and the two scaly skin-folds that outline the cloaca.

Males fight savagely, and cannot be housed together.  A single male may be kept with multiple females.  Gecko skin is delicate, and bite injuries may occur during courtship and copulation; check also for dominance battles among females.

Stimulating Reproduction

In the wild, breeding likely extends through much or all of the rainy season (March to May through October, depending upon locale).  Increasing the frequency and duration of daily misting in the spring will encourage captives to come into breeding condition.  Novel food items and increased dietary variety should also be introduced at this time.  Some have reported that removing and re-introducing a male will stimulate interest.

Lowering temperature and humidity slightly during the fall and winter may also be useful, but is not critical (please write in for details).

The Eggs

Gravid female swell noticeably, and their 2 eggs will be visible through the skin in time.  A well-fed female may produce 3, or possibly more, clutches of 2 eggs each.  I’ve recorded inter-clutch intervals of 2-3 weeks, but this time period is likely affected by many factors.

Eggs are affixed to bark, glass or stout plant leaves.  Be sure to provide ample nesting sites that can be removed for incubation, as the eggs are often broken during attempts to peel them from the deposition surface. Corkbark slabs are ideal, as they can be cut to fit incubators if need be.

Incubation

Suitably-sized plastic terrariums, with the ventilation ports sealed, make ideal incubators.  Eggs under my care generally hatched in 60-80 days at 82-85 F, but temperatures of 70-90 F, and incubation times of 30-90 days, have been reported.

Eggs deposited on glass are difficult to remove; I’ve incubated House and Day Gecko eggs on glass by affixing a cup containing damp sphagnum moss over the eggs, but this is not an ideal situation.

The Young

Hatchlings average a bit over 2 inches in length and may be reared on fruit and other flies, small crickets and roaches, silkworms, moths, termites and similar insects (please see diet comments above).

 

 

Further Reading

Gecko Gliding Explained: excellent, comprehensive articles with photo of geckos “in flight”

Incubating Reptile Eggs

Kuhl’s Flying Gecko: great photos

Ptychozoon kuhli image referenced from wikipedia and originally posted by Manuel Werner

 

Crickets and Carotenoids – Study Examines Cricket Nutrient Levels

veggiesCaptive insect-eating reptiles and amphibians (and perhaps invertebrates) are often plagued by nutritional deficiencies. A highly-varied diet is a great way to ensure adequate nutrition, but most keepers have access to only a few feeder-insect species; gut-loading (providing nutritious diets to feeders) is helpful, but detailed studies are lacking. While touring several Japanese zoos a few years ago, I was intrigued by the number of cricket species being bred as herp food, and resolved to investigate the species and diets I saw in greater detail. A recent article in Zoo Biology (2011, V. 30), which provides insights into carotenoid supplementation in three different cricket species, has re-sparked my interest. I’ll summarize below.

Carotenoids

Carotenoids are pigments that occur in plants. Animals, as far as is known, cannot manufacture carotenoids but rather must obtain them through their diet.

Carotenoids benefit the immune system by acting as antioxidants, function in the reproductive and other systems, and are believed partially responsible for the health benefits enjoyed by people who regularly consume fruits and vegetables.  We know little of their role in reptile and amphibian health, but many zoo nutritionists believe them to be important. Read More »

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