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

Our favorite animals’ own holiday, Reptile Awareness Day (RAD), will soon be upon us. On Wednesday, October 21st, herp enthusiasts can participate by doing something special for reptiles – educate someone about reptiles, clean up a reptile habitat, do something special for your pet, make a donation to a conservation organization…the possibilities are endless.

The Bronx River as Herp Habitat?

I’ve been involved in a few such endeavors over the years. One of the most gratifying was in conjunction with Bronx River Restoration. Neighborhood children were recruited to help remove debris that had accumulated along that part of the Bronx River that passes through the Bronx Zoo. A surprising array of reptiles and amphibians (i.e. snapping, painted and musk turtles, green and bull frogs, dusky salamanders) live along the river, but they need a hand on occasion.

We also trimmed overgrown banks to let in sunlight and improve basking opportunities for resident Eastern painted turtles and added tree stumps to the shallows. On return visits to the river, the children were happy to see both turtles and water snakes utilizing the new basking spots.

Water Snakes in NYC

Another surprisingly effective project that I enjoyed was the reintroduction of northern water snakes to the banks of the Bronx River and nearby ponds. Working on conjunction with several wildlife agencies, I collected water snakes from approved areas and released several gravid females. I also held back a few animals for captive breeding, and released the young (1 huge female gave birth to 89 live young, a near record!).

I’m delighted to report that the water snakes are breeding in their new habitat. If this can be accomplished in the center of the country’s most densely populated city, just imagine the potential that exists elsewhere!

Please Note: Reintroduction programs must be carefully researched and approved by your state Fish and Wildlife Agency.

Have Fun, Help Reptiles and Win Prizes!

Forgotten Friend Reptile Sanctuary, a reptile rescue and education organization located in Elizabethtown, PA, is sponsoring a contest in support of Reptile Awareness Day (RAD). So lending a hand to reptiles will not only feel good…it may just earn you some great prizes as well (Including a $50 gift card from That Fish Place/That Pet Place)!

To enter, simply post a note describing your “reptile friendly” good deed on Forgotten Friend’s site.

Radio Broadcasts

Anyone in the Central Pennsylvania area should be sure to tune in to the morning shows at FM 97 or WJTL FM 90.3 on October 21st – Forgotten Friend Reptile Sanctuary representatives will discuss their important work and suggest ways that we can help to make the world a better place for our reptile friends.

Amphibian Awareness Day?

We don’t have an Amphibian Awareness Day yet, but please don’t forget that frogs, salamanders and caecilians also need a hand. As you can see from the photo, even the youngest herpetologists among us can express real tenderness towards small creatures (the sturdy little fellow pictured here usually goes through life like a bulldozer!). Children are the conservationists of the future – include them in your hobby if at all possible.

I remember well my shock when the news concerning temperature dependant sex determination (TDSD) among reptiles first broke.  Imagine…a turtle or crocodile egg can develop as either a male or female, depending upon the incubation temperature!  Well, it now seems that at least one species of lizard, the three-lined skink (Bassiana duperreyi), complicates matters even further.

Egg Size and Sex

Writing in the June, 2009 issue of Current Biology, University of Sydney biologists have revealed that large skink eggs develop into females, while small eggs become males.  Furthermore, removing yolk from a large egg resulted in a male hatchling, despite the fact that female genes were present; adding yolk to a small egg over-rode the effect of the male genes already in the egg, producing instead a female.

Temperature and Sex

Extreme nest temperatures, it seems, can also affect the hatchlings’ sex, regardless of its genetic makeup, resulting in xx chromosome males (males are usually xy) and xy females (females are typically xx).

Survival and Conservation Implications

The question that begs answering, of course, is why has this lizard evolved such a unique and complicated reproductive strategy?  Researchers are now looking into its ecology to determine the answer.

Understanding such matters has greatly assisted those working to conserve reptiles and amphibians.  Knowing the parameters of TDSD has allowed us to pick and choose the sexes of highly endangered species being bred in zoos, so that a favorable sex ratio can be maintained.

Of course, there were some problems early on.  I was working with green sea turtle head-start programs in Costa Rica when TDSD first came to light.  The organization I was with had been gathering sea turtle eggs for 30 years, incubating them, and then releasing the young when they had grown past the vulnerable stage.  Great in theory…but by using a single incubation temperature, we may have produced only female green turtles for the entire 3 decades!

Further Reading

You can read more about the natural history of the three-lined skink and its relatives at http://www.jcvi.org/reptiles/species.php?genus=Bassiana&species=duperreyi.

A Control Program Backfires
Please see Part I of this article for background information. With introduced green iguanas (Iguana iguana) driving endangered burrowing owls from their nests and raccoons (Procyon lotor) devouring sea turtle eggs, the Florida Department of Environmental Protection initiated control measures. At a preserve in Dania Beach, an intensive trapping and collection campaign greatly reduced the numbers of both species, but an unexpected consequence of these efforts soon became apparent.Within a year of the raccoon numbers being brought under control, iguana populations skyrocketed. In one area of the park, researchers counted 626 iguanas per square kilometer (0.4 square miles)…an unprecedented density for any lizard species!

It seemed that raccoon predation had been a very effective control on iguana numbers. Although hawks, gray foxes, night herons, alligators and other animals prey upon iguanas, only raccoons take eggs, hatchlings and sub-adults in significant numbers.

Iguanas…Here to Stay?
Young iguanas are now especially common at the site, pointing towards an even greater population increase in the future. Hand-collection, although possible, is a daunting task, so biologists are looking into alternate control measures. Meanwhile, spurred by ample food and little competition, lizards as young as 2 years of age are laying eggs.

In Belize, black rats effectively control one green iguana population by taking nearly every egg laid. However, Florida’s parks already have enough problems without black rats…in fact, their notorious cousin, the Norway rat, is already a resident of many!

Further Reading
It was my good fortune to work with green iguanas in a natural, if somewhat unusual (i.e. treeless) habitat. Please see my article, The Green Iguana on the Venezuelan Llanos  for the story.

To learn more about the challenges and rewards of keeping these impressive lizards, please check out our care guide, Green Iguanas.

Shocking as it may be to anyone with even a passing awareness of conservation issues, tiger salamander larvae (Ambystoma tigrinum) are still widely used as fishing bait throughout much of the USA.  Run through with hooks while alive, the 6-10 inch amphibians are wildly popular with anglers seeking bass, pickerel and other fishes.

Disease and the Bait Trade

Recently (April, 2009), biologists at the National Science Foundation announced that a significant percentage of larvae in the bait trade have tested positive for the deadly Chytrid fungus Batrachochytrium dendrobatidis.  This fungus has decimated amphibian populations on nearly every continent, and is responsible for the extinctions of local populations and, most likely, entire species.

Herpetologists are working feverishly to control its spread, but are as yet unable to understand why the fungus has become such a devastating problem in recent years.  Often, the only hope for amphibians in its path is captivity   – colleagues of mine recently collected an entire population of Panamanian golden frogs, but the long-term outlook is quite dim.

Virulent ranaviruses, which quickly kill many amphibians, have also been identified in larvae sold in bait shops in Arizona, Colorado and New Mexico.

Hybridization

As if the all this were not enough, the release of bait trade salamanders has resulted in the hybridization of critically endangered California tiger salamander populations (released barred tiger salamanders mated with the California subspecies).

Hybridization threatens survival by altering critical components of the genome.  For example, when various subspecies of ibex (mountain goats) were released together in Spain, the resulting hybrids gave birth during the winter, and the population became extinct.

Getting Involved

Partners for Reptile and Amphibian Conservation http://www.parcplace.org/, an organization of professional herpetologists and interested citizens, supports numerous research programs.  Please be in contact to learn more about this issue and their many interesting volunteer opportunities.

Next time I’ll discuss other threats to tiger salamanders, their conservation status, and problems regarding food market bullfrogs.  

Further Reading

Please see my book Newts and Salamanders  for information on the natural history and captive care of tiger salamanders and their relatives.

Image referenced from morguefile.

Recently I wrote about some exciting information that has recently come to light concerning the effectiveness of Zoo Med UVB lamps (please see my article Product Review: The Zoo Med Reptisun 10.0 High Output UVB Lamp and 5.0 UVB Lamp, Part I and Part II for further information).

One drawback inherent in all UVB lamps (bulbs) is the fact that the lamp will continue to burn brightly long after its UVB output has declined or even ceased.  To further complicate matters, the effective life varies from model to model, and among different manufacturer’s lamps.

Zoo Med has recently introduced a service wherein customers are reminded of lamp replacement dates via email.  Lamp purchasers register the purchase date, model, terrarium type and species kept…based upon this information, the company determines the ideal time to replace the lamp and sends an email notice as that time approaches.  Advances in technology that affect lamp life will be incorporated into the system.

A tip: if you have a large collection, you may wish to invest in a small UVB meter.  UVB output and useful life can vary even among lamps manufactured by the same company.  Actually monitoring UVB production will allow you, in some cases, to leave a lamp in place after its usual expiration date.  Also, once UVB output has declined, you can move the lamp to a situation where it can be placed closer to a basking site or perhaps use it for a species that has lower UVB requirements.

You can read about Zoo Med’s new program at:

http://zoomed.com/Join/UVBSignup.php