How Reptiles, Amphibians and Spiders “Celebrate” Valentine’s Day

Mating psir of jumping spiders

Uploaded to Wikipedia Commons by Kaldari

As Valentine’s Day draws near, I thought it might be time to give some competition to the inevitable stories that will surface concerning monogamous mammals and “gift-giving” birds. To be sure, penguins presenting mates with rocks are cute, but how many folks know about the far-more complex (and often longer-lasting!) pair bonds formed by reptiles and amphibians, and the risky – sometimes “deceitful” – gifts borne by some amorous spiders? Recent research has turned-up frogs that mate for life, skinks that build communal dwellings, monogamous alligators, nest-defending monitor pairs and many other astonishing examples of fascinating long-term relationships among our favorite creatures.


You Call This a Gift!?

Male invertebrates of many species utilize “nuptial gifts” to convince females of their desirability as mates…or, perhaps, to avoid becoming a meal as opposed to a father! But matters become a bit complex where the aptly-named Gift Giving Spider (Paratrechalea ornata) is concerned. In one study of 53 courting males, 70% of the silk-wrapped insects they presented to females were found to be “leftovers” – hollow exoskeletons whose contents had already been consumed by the conniving suitors!


Scorpion fly

Uploaded to Wikipedia Commons by Richard Bartz,

Thin male spiders usually offered worthless husks, while well-fed males presented entire insects. Follow-up lab studies revealed that females accepted both intact and empty gifts (it takes time for them to unwrap the insects and discover the con-artists!), but were more likely to mate with heavier, well-fed males, regardless of the condition of their gift. While it seems that thin male spiders bearing useless gifts may be “getting away with something” if they mate successfully, it may be that females have the last laugh. Female spiders mate with several males, and may be able to store sperm. As occurs in some other species, the female may then somehow control which male’s sperm ultimately fertilizes her eggs.


Mate Fidelity and Cooperation among Amphibians and Reptiles

It has long been suspected that certain reptiles and amphibians form long-term relationships and engage in cooperative behavior. Several recent studies have confirmed this…and some have taken herpetologists completely by surprise. Several of my favorites follow…please post your own below.


Mimic Poison Frog

Uploaded to Wikipedia Commons by Gabsch

Mimic Poison Frog: two parents needed

Perhaps the most surprising has been the discovery of the world’s only completely monogamous amphibian – Peru’s Mimic Poison Frog (Ranitomiya imitator). Driven by the need for close cooperation in raising the tadpoles, pairs form lifelong bonds.


The tadpoles are deposited in tiny, nutrient-poor pools within bromeliads, and would not survive without the unfertilized eggs provided by their mothers as food. Many other Poison Frogs do the same, but Mimic males stay near tadpole pools and call to their mates when the tadpoles need to be fed (how they know when to call remains a mystery)! A closely-related frog that places its tadpoles in nutrient-rich pools is not monogamous.


Great Desert Skinks: hard working, “semi-faithful” males

Although at least twenty lizard species live in family groups, only the Great Desert Skink (Liopholis kintorei) is known to cooperatively construct complex, long-term dwellings inhabited by several generations. Researchers from Australia’s Macquarie University have discovered that these subterranean homes have up to 20 entrances and separate latrine areas, and may span 50 feet or more. Tunnel maintenance duties are carried out by family members based upon size, with the largest individuals doing most of the “heavy lifting”, but all contribute some effort.


Mated pairs of Great Desert Skinks, which are native to the red sand plains of central Australia, remain together for years. Females seem to copulate only with their mates, but 40% of the male skinks father young “outside of their primary relationship”.


Rosenberg's Monitor

Uploaded to Wikipedia Commons by Paul Asman and Jill Lenoble

Rosenberg’s Monitors: tag-teaming nest predators

A 16-year-long study of Rosenberg’s Monitor (Varanus rosenbergi) on Australia’s Kangaroo Island has revealed that females are sometimes joined by males when guarding their nests. Nest-attending females attack intruding male Rosenberg’s Monitors (the main threat to eggs) whether or not their mates are present…when mates are on hand, they assist females in repelling others. Males were also observed helping their mates to cover nests on several occasions.


Shingleback Skinks

Uploaded to Wikipedia Commons by Coojah

Shingle-Backed Skinks: absence makes the heart grow fonder

The Shingle-backed Skink (Tiliqua rugosa / Trachydosaurus rugosus), much loved by lizard keepers, has the distinction of being the first documented monogamous lizard. What’s more, paired individuals live solitary lives for up to 10 months of the year, but they re-connect each breeding season. Field research has shown that pairs spend an average of 43 days together during September and October, usually in close physical proximity, at which time they mate (and, one would imagine, sort out bills, “to do” lists and such!). They then go their separate ways, having little or no contact with one another until the following September.


Female alligatoir with young

Uploaded to Wikipedia Commons by Catholic 85

Faithful Female Alligators

Biologists working with American Alligators (Alligator mississippiensis) in Louisiana’s Rockefeller Wildlife Refuge were surprised to find a high degree of mate fidelity in their study population. Writing in the October, 2009 issue of Molecular Ecology, the researchers explained that 70% of the female alligators studied over a 10 year period mated with the same male each year. This is the first time such behavior has been documented in any Crocodilian, and is rendered even more interesting by the fact that the refuge supports a very dense population of alligators, and females freely move through the territories of many males.



Further Reading

Great Desert Skink Communal Dwellings

Monogamous Frogs


Crested Gecko Care: Breeding Crested Geckos

In the past 20 or so years, the Crested Gecko (Correlophus/Rhacodactylus ciliatus), has gone from “presumed extinct” to being such a common pet that it may actually rival the Leopard Gecko in popularity! In addition to their interesting ways, innate “charm”, and extreme hardiness, these New Caledonian natives are also proving extremely easy to breed in captivity. Yet as I receive questions and review related articles and internet forums, it seems that some confusion exists on this topic. As Crested Geckos can provide a wonderful introduction to lizard breeding, today I’d like to review how best to get started. Also, since even un-mated females can produce eggs, and may suffer fatal impactions if not properly cared for when gravid, it is important for all owners to understand the basic principles of Crested Gecko reproduction.


Mating pair of Crested Geckos

Uploaded to Wikipedia Commons by Steve Lagou

Do I Have a Pair?

Crested Geckos show sexual dimorphism earlier than do many other lizards. By age 6 months or so, males will exhibit two easily-seen bulges near the cloaca, evidence of the internal male sex organs, or hemipenes. Small femoral and pre-anal pores may be visible even earlier. However, these may not be evident to folks who have not seen a good many mature males of this or related gecko species.


Unlike many lizards, Crested Gecko pairs may be housed together year-round. However, females that are not in breeding condition may be injured by males during unsuccessful copulation attempts. A bit of biting is normal at this time, but in small terrariums, or those lacking cover in the form of logs, plants, etc., injuries may occur.


Reproductive Age

Captive reptiles of many species often reach adult size faster than they might in the wild, but this does not always mean that breeding is possible or advisable.


Crested gecko

Uploaded to Wikipedia Commons by annakilljoy,

Female Crested Geckos may become sexually mature by age 8 months or so, but it is best to forestall breeding until they are at least 1 – 1½ years old. Most successful long-term breeders use 40 grams as a safe weight for first-time breeding females. Males may be bred at the same or a slightly younger age, and are generally a bit lighter in weight than females.


Stimulating Reproduction

There doesn’t seem to be much in the way of detailed field studies of Crested Gecko reproduction. Judging from the temperature profile of their habitat, they most likely breed throughout New Caledonia’s warm season (November to April), when temperatures average 74-85 F.


Habitat type

Uploaded to Wikipedia Commons by Adbar

Pets kept in temperate regions are usually stimulated to breed by local seasonal changes, beginning as the weather warms in spring and ceasing in autumn. In tropical and semi-tropical regions, well-fed females may continue to deposit eggs throughout the year. This can deplete calcium stores and otherwise impact long-term health. Cooling geckos to 68 F by day and 65 F by night, and reducing the daytime period to 10 hours, has been useful in stopping reproduction (however, this must be done gradually…please post below if you need further information).


Egg Deposition

Female Crested Geckos deposit clutches of 2 eggs. They usually produce multiple clutches, separated by approximately 30 days (but this number varies widely), each breeding season. Three to 5 clutches are generally considered as being typical for well-fed pets, but up to 10 have been reported.


Leaping gecko

Uploaded to Wikipedia Commons by Alfeus Liman

In naturalistic terrariums, eggs may be secreted beneath the substrate at the base of plants, cork bark, or other cover. Gravid females are sometimes seen digging in several spots before deciding on a nest site.


Even if nesting sites are available in the terrarium, boxes or caves provisioned with a mix of moist sphagnum moss and soil should always be provided. This will simplify egg retrieval (if they are used, of course!) and will assure that there will always be a suitable nest site. Female geckos that cannot find a site to their liking may retain their eggs, which will eventually lead to a fatal infection (egg peritonitis).


Also, bear in mind that female Crested Geckos are able to store sperm. Those purchased as adults, or separated from a male, may still produce fertile eggs. As mentioned above, females that have not mated may also develop eggs, which must be deposited.


Stay alert for signs that a female may be egg-bound – lethargy, swollen abdomen, straining – and see a veterinarian if this occurs.


248523Egg Incubation

Crested Gecko eggs have been successfully incubated under a wide range of conditions. Here again they vary from many reptiles, as the eggs are extremely resilient and develop well at unusually-low (by lizard standards) temperatures.


As with most eggs, I favor course vermiculite or pearlite as an incubation medium. A water: substrate mix of 1:1 by weight works well.  The eggs may be incubated in an room with an appropriate temperature range, or a commercial reptile egg incubator.  Please see the article linked below for information on a simple method of calculating and tracking water content.


I haven’t found anything definitive concerning the effect of incubation temperatures on hatchling sex, but several anecdotal notes report that females predominate at temperatures of 77-80 F, males at 82 F, and mixed sexes at 70-76 F (the range most favored by experienced breeders). Incubation temperatures exceeding 84 F are said to kill the embryos.


Incubation periods range from 65-120 days, depending upon temperature and, in all likelihood, humidity levels and other factors.


Please post below for information on rearing young Crested Geckos.


Further Reading

Crested Gecko Substrates: Avoiding Impactions

New Caledonia Giant Gecko Care

Rear Fanged Snakes: Fascinating, Venomous, and Not a Good Pet Choice

South American Hognosed Snake

Uploaded to Wikipedia Commons by Matt872000

The term “rear fanged” is applied to a variety of unrelated snakes that possess a venom-producing gland and 1-3 enlarged, grooved maxillary teeth in the rear of the mouth. We do not yet know how many species possess these venom-conducting teeth (“rear fangs”), but evidence indicates that snake venom evolved some 60 million years ago – before non-venomous snakes came into being. Therefore, all present day species may have evolved from venomous ancestors, and may possess at least the traces of venom glands. The rear-fanged snakebites I’ve dealt with in the course of my career have elicited only mild reactions. Some rear-fanged species, however, have caused fatalities – two very “famous” fatalities, in fact (please see below).


Snakes Best Kept in Zoos

As individual sensitivities and other factors can greatly affect one’s reaction to a bite, even “mildly venomous” species must be considered as potentially dangerous. A lifetime of experience as a zookeeper and herpetologist has taught me that it is impossible for a private snake owner to adequately prepare for or treat a venomous snakebite at home, or, prior to a bite, to arrange for treatment in a hospital.


Tentacled Snake

Uploaded to Wikipedia Commons by Rishaada

Until we learn more about them, rear fanged snakes are best considered as suitable for display in zoos rather than private collections. Tentacled Snakes (Erpeton tentaculatum) and certain others may be an exception, but I advise consulting a herpetologist and an experienced medical doctor if you feel compelled to acquire a rear-fanged snake of any species.



Uploaded to Wikipedia Commons by Rishaada




Rear fanged snakes are classified in the huge family Colubridae (the “Typical Snakes”), but are not necessarily closely-related to one another. The term is applied to a variety of species that possess the venom-producing Duvernoy’s Gland. One, two, or three of the maxillary teeth in the rear of the mouth are enlarged and bear grooves on their front surfaces. Venom released by the Duvernoy’s Gland flows down these grooves and into a prey animal or foe. A period of “chewing”, in the manner of cobras and other Elapids, may be necessary in order to fully discharge the venom.


This method of introducing toxins into a wound is rather ineffective when compared to that employed by rattlesnakes and other Viperids. Also, many rear fanged species produce venom that is most or only effective against the specific animals upon which they feed. Therefore, not all present a threat to people.


Twig Snake

Uploaded to Wikipedia Commons by Kwamikagami

However, much remains to be learned. For example, Boomslangs (Dispholidus typus) and Twig Snakes (Thelotornis kirtlandi) were not widely believed to be dangerous until each killed a prominent herpetologist! (I use “widely” because both were feared by local people).



At an adult size of 8 inches, North and South America’s Crowned Snakes, (Tantilla spp.), are the smallest rear fanged species known.


Mangrove snake

Uploaded to Wikipedia Commons by Seshadri.K.S

Widely-distributed through much of Southeast Asia, the 7-foot-long Mangrove Snake (Boiga dendrophila), is the largest. This spectacular snake’s size and striking coloration render it much desired in the trade, and many are held in private collections. Those I’ve kept in zoos have remained high-strung and difficult to work with. Fatalities have not, as far as I know, been attributed to their bites, but large individuals can store up a substantial quantity of venom – I’d leave these beauties alone!



Many rear fanged snakes have evolved toxins that specifically target reptiles and amphibians, and may specialize in hunting lizards (Mexican Vine Snake, Oxybelis aenus), frogs and toads (Malagasy Giant Hog-Nosed Snake, Lioheterodon madagascariensis) or fish (Tentacled Snake, Erpeton tentaculatum).


Green Vine Snake

Uploaded to Wikipedia Commons by Dimitri Eggenberger.

Others, such as the Mangrove Snake (Boiga dendrophila), are generalists that consume a variety of creatures, including birds and mammals. The tiny Crowned Snakes, Tantilla spp., limit their diet to earthworms, centipedes, beetle grubs, and other invertebrates.


“Harmless Snakes” with Venom

Recent research has shown that 2,000 or more snake species, many considered “harmless”, likely produce true venom. Most do not have efficient rear fangs, and produce toxins that pose no danger to people, but this does point out the need for caution and research.



Further Reading

Venomous Snakebites: My Experiences and a New Study

The USA’s Most Dangerous Snake?


Rosy Boa or Colombian Red-Tailed Boa? Choosing the Best Snake Pet

Large adult Boa Constrictor

Uploaded to Wikipedia Commons by Pavel Ševela

Boa Constrictors have been pet trade staples for decades. Of the 10 described subspecies, the Colombian or Red-Tailed Boa (Boa constrictor constrictor) is the best known, and is in fact one of the most popular snake pets. Commercially bred in huge numbers, the Colombian Boa is an excellent choice for some, but not all, snake enthusiasts.

North America’s Rosy Boa (Lichanura trivirgata), on the other hand, has only come into its own recently as a pet, but interest in now skyrocketing. Those with limited space who are seeking a “big snake in a small package” need look no further than this inoffensive beauty.

In the following article I’ll compare the care needs of Colombian and Rosy Boas, so that you’ll be able to plan ahead and maximize your pet-keeping experience and your snake’s quality of life. Detailed care information is provided in the articles linked under “Further Reading”. As always, please also post any questions you may have, and let me know which species gets your vote.


Rosy boa

Uploaded to Wikipedia Commons by Theodore Garland, Jr.


Although individual personalities vary, both adapt well to gentle handling. Rosy Boas tend to hide their heads when frightened, and their smooth, glossy scales may render handling a bit tricky. As with any snake, care and adult supervision must be exercised, and the animal’s head should never be allowed near one’s face.


Colombian Boas are not domesticated animals and must never be handled carelessly, as even long-term pets may react to scents or vibrations that people do not perceive. Bite wounds from Colombian Boas can be severe, and pets should never be carried about one’s neck (other similarly-sized constrictors have caused human fatalities by tightening quickly about a handler’s neck). Two experienced adults should always be on hand when specimens over 6 feet in length are fed, cleaned or handled.



Colombian Boas average 5-8 feet in length, and are stoutly built. However, some individuals grow quite a bit larger – up to 13 feet, 6 inches and 14 feet for the record holders, both captured in Surinam.


Averaging only 24-30 inches in length but also heavily-built for their size, Rosy Boas are obviously much easier than Colombian Boas to house and maintain.


Boa constrictor in natural habitat

Uploaded to Wikipedia Commons by Belizian

Activity Levels

Neither is overly active, but they regularly move between basking sites and shelters, and are likely to wander about the cage when hungry.


Life Span

The published longevity for a Colombian Boa is just over 40 years; pets regularly survive into their 20’s and 30’s.


The published longevity for a Rosy Boa is 29+ years (living at time of publication), and many captives approach and exceed age 20.


Newborn boa

Uploaded to Wikipedia Commons by DestructiveEyes

Breeding Potential

Both species breed reliably, and make an excellent introduction to this fascinating aspect of reptile-keeping. I especially like the fact that they bear live young, doing away with the time, expense and worry (for us!) of egg-incubation.



The purchase price for a normally-colored individual is similar for both snakes. Prices increase for rare or unusual color morphs – to $5,000 or more for “special” Colombian Boas!


However, the normal coloration of each species is spectacular, and natural variations, especially for the Rosy Boa, are seemingly endless. Several Rosy Boas that I encountered while studying insects in Baja California, which were blue-gray and marked with 3 pinkish-orange stripes, stand out as being among the most beautiful snakes I’ve seen.


The Colombian Boa’s great size makes it vastly-more expensive to keep when compared to its smaller cousin, the Rosy Boa.


Rosy boa, adult

Uploaded to Wikipedia Commons by Shane O. Pinnell

Terrarium Size (single adult)

Colombian Boa: 250-300 gallon terrarium or a huge custom-built cage


Rosy Boa: 20-30 gallon terrarium



Colombian Boa: 75-85 F, with a basking site of 90 -95 F; basking bulb and sub-tank pad recommended.


Rosy Boa: 75-85 F, with a basking site of 90-95 F



Food intake will vary among individuals and with temperature, season, life cycle stage, and other factors. Both accept pre-killed rodents.


Rosy Boa feeding

Uploaded to Wikipedia Commons by Cole Shatto

Colombian Boa: 1 appropriately-sized mouse each 7-10 days for youngsters. Adults do fine when offered an appropriately-sized rat each 10-14 days. Some keepers use guinea pigs or small rabbits for especially-large adults.


Rosy Boa: Fuzzies and young mice are preferable to adult mice (Rosy Boas have rather small heads and their jaws are ill-suited to swallowing large meals). Youngsters should be fed each 7-10 days, adults each 10-14 days.




Further Reading

Breeding the Rosy Boa

Boa Constrictors and Their Relatives: Care and Natural History




Eastern Painted Turtle Care: Keeping the USA’s Most Beautiful Turtle

PAINTED TUR, SMILEThose of us who are accustomed to seeing Eastern Painted Turtles (Chrysemys scripta scripta) in the wild and captivity sometimes take their beauty for granted. In my youth, I was able to find them quite easily near my Bronx home, and was surprised by the overseas demand when I began working for a local animal dealer. But upon close inspection, it’s easy to see why these aptly-named turtles are wildly-popular in zoos and private collections worldwide. In addition to their brilliant coloration, Eastern Painted Turtles make hardy, long-lived and responsive pets (if given proper care!). They have all the qualities that have made Red-Eared Sliders so popular, but their smaller size and calm demeanor renders them a far better choice for most turtle enthusiasts.


320px-Eastern_Painted_Turtle_(Chrysemys_picta_picta)Natural History

The Eastern Painted Turtle’s range extends from southern Canada along the eastern seaboard of the USA to Georgia, and west to central Alabama. Three subspecies – the Southern, Midland and Western Painted Turtles – range across southern Canada and through most of the USA to northern Mexico. All hybridize where their ranges overlap, and in captivity.


Type habitat

Uploaded to Wikipedia Commons by FWS

Painted Turtles favor slow-moving, well-vegetated waters, and are most commonly encountered in swamps, marshes, river oxbows, creeks, and small ponds on farms and even golf courses (I caught my first specimen, as a child, by hopping a golf course fence and sloshing through its tiny pond – that incident remains my only golf-related experience!). I once was surprised to find a hatchling in a tidal river on Long Island, but have since learned that they are known to enter brackish water.


Turtle Behavior in Captivity

Like many semi-aquatic turtles, Eastern Painteds quickly learn to associate their owners with food, and will paddle over to beg when you approach. Ever-alert, wild individuals plunge from basking sites when startled, but pets are generally quite fearless. Most feed readily from the hand, and they may even reproduce.


Young painted turtle

Uploaded to Wikipedia Commons by US Bureau of Land Management


Female Eastern Painted Turtles reach 7-9 inches in length, while males generally top out at 5 inches. An adult female will require a 30 to (preferably) 40 or 55 gallon aquarium; a male might make due in a 20 gallon “long-style”, but more room is preferable.


Zoo Med’s Turtle Tub is an excellent option for larger individuals. Plastic storage bins, if properly outfitted, may also be used.


Wading pools are often easier to manage than aquariums. Koi ponds sometimes contain shelves meant to hold plants; these work well as turtle basking areas. Outdoor housing is ideal, assuming that raccoons and other predators can be excluded.



Uploaded to Wikipedia Commons by Tony Gamble

Although highly aquatic, Painted Turtles need a dry surface on which to bask. Commercial turtle docks will suffice for smaller specimens. Cork bark, wedged or affixed via silicone to the aquarium’s sides, is a good option for adults.



Turtles are messy feeders and very hard on water quality. Submersible or canister filters are necessary unless the enclosure can be emptied and cleaned several times weekly (I’ve found the Zoo Med Turtle Clean Filter to be ideal). Even with filtration, partial water changes are essential.


Southern Painted Turtle

Uploaded to Wikipedia Commons by Suzanne L Collins (CNAH)

Removing your turtles to an easily-cleaned container for feeding will lessen the filter’s workload and help to keep the water clear.



Bare-bottomed aquariums are best, as gravel traps food and wastes, greatly complicating cleaning. If gravel is used, it should be of a size too large to be swallowed.



Heliothermic turtles (those that bask) require UVB exposure in captivity. Natural sunlight is the best UVB source, but be aware that glass filters-out UVB rays.


If a florescent bulb is used (the Zoo Med 10.0 Bulb is an excellent product), be sure that the turtle can bask within 6-12 inches of it. Mercury vapor bulbs broadcast UVB over greater distances, and also provide beneficial UVA radiation.


Western Painted Turtle plastron

Uploaded to Wikipedia Commons by Matt Young


Water temperatures of 75-80 F should be maintained. An incandescent bulb should be used to warm the basking site to 88-90 F.



Painted turtles will eat or harass fishes, newts and aquatic frogs.


Individuals of the same sex may get along, but aggression often develops so be prepared to house them separately. It’s difficult to keep pairs together long-term, as the males’ continual mating attempts usually lead to stress and bite wounds.



Painted Turtles begin life as carnivores but increasingly consume aquatic plants as they mature. Pets favor animal-based foods, but should be encouraged to eat plants; a fasting period will tempt them to sample new items.


Dandelion, kale, mustard and collared greens, romaine and other produce should be offered. Aquatic plants such as Elodea, Anachris and Duckweed may also be accepted. Spinach and beet leaves are high in oxalic acid and have been implicated in health problems.


mediaZoo Med Aquatic Turtle Food and Reptomin Food Sticks provide excellent nutrition and can serve as 50-75% of the diet. Other commercial aquatic turtle diets and treats are also worth investigating.


Natural foods should always be included in turtle diets. Whole freshwater fishes such as minnows and shiners are the best source of calcium for turtles. Offer fish at least once weekly, but use goldfishes sparingly as a steady goldfish diet has been implicated in liver ailments in other species.


Other important food items include earthworms, krill, freeze-dried river shrimp and crickets, waxworms and other insects.



Wild females become sexually mature at age 5-10, males at age 3-5. Courting and breeding occurs in May and June, and females deposit 1-4 clutches of eggs (1-15 eggs in total) between May and July. Late-hatching young may overwinter in the nest and emerge the following spring.


Captive conditions may alter all of the above, so please write in for detailed information on how best to breed your pets in their particular environment.


Health Considerations

Salmonella bacteria, commonly present in turtle digestive tracts, can cause severe illnesses in people. Handling an animal will not cause an infection, as the bacteria must be ingested. Salmonella infections are easy to avoid via the use of proper hygiene. Wash your hands with warm, soapy water after handling any animal. Please speak with your family doctor concerning details, and feel free to write me for links to useful resources.




Further Reading

Providing Nesting Sites to Female Turtles

Commercial Turtle Diets: Pellets, Shrimp and Prepared Foods

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