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Chat Transcript
Dr. Mark Seward 2/23/99

Jeff Barringer - Tonights guest is Dr. Mark Seward and tonight the topic is Gilas and Beaded Lizards. Welcome Dr. Mark Seward
Dr. Mark Seward - Thanks, it's good to be here.

Jeff Barringer - Im going to start off with the first question.....
Jeff Barringer - What got you interested in Gilas and Beadeds
Dr. Mark Seward - I have always had a keen interest in Gilas. They were always the dream reptile for me.

John Hollister - Mark, is there a reliable non-invasive way to sex heloderma? adults, that is?
Dr. Mark Seward - The ability to easily and accurately sex Gilas has been elusive. I have been working very hard on a DNA based test for sexing Gilas at any age. The best way to sex Gilas without this test is by behaviour.

amazoa - The tails of Gilas I've heard store fat do you see it disappear some during the gestation of the eggs? Is it true the gestation is only around 30 days for Gilas?
Dr. Mark Seward - Egg production is a tremendous energy investment for female Gilas. You can see a visible reduction in tail girth during egg development. In my experience, gestation is about 42-55 days.
amazoa - thanks
which one is easier to care for gila or beaded lizards,and why are they expensive to buy
Dr. Mark Seward - Husbandry is identical for both species. Beaded lizards are larger and more aggressive. The issue of cost is simply supply and demand. They are protected throught their range and can not be collected from the wild. Also, captive propagation has been inconsistant at best. thanks so much

boidguy - do you find male to male combat to be reqired for gila breeding? and what kind of sex ratios do you keep together during breeding trials?
Dr. Mark Seward - The question of male combat is an interesting one. Many have suggested that it is necessary for captive reproduction. I am of the complete opposite opinion. Male-male combat is an important component of social interactions in free ranging Gilas. However, in captivity, the dynamics of combat are very different from what occurs in the wild. In captivity, the losing Gila has no avenue for excape and will frequently combat at the exclusion of any other activity.

Chris Koester - FYI Mark the recent issue of the ARAV bulletin had a paper detailing the aforementioned sexing technique of Heloderms via ultrasonography....I can send you a copy if you'd like. :) Now my question: Exactly how many Gilas do you keep/breed currently?
Dr. Mark Seward - Ultrasound does seem to be a good way to sex adult Gilas if one has experience with it. My group currently consists of 32 Gilas. Next week I am going to the Arizona-Sonora Museum to pick up a group of Gilas for a research project, so my group will increase.

corucia - IWe attempted the ultra sound technique on 4 sub adult gilas today .... any advice on techniue?
corucia - were following procedure given in a paper written by Dr. Pat Morris
Dr. Mark Seward - I personally have no first hand experience with ultrasound. Sorry.

Gaylon Holmes - Hello, Doctor. What is your current protocol regarding egg incubation?
Dr. Mark Seward - The most important thing, in my opinion, is to keep them dry and not to warm. I start out with a 1:2 or 1:3 ratio (by weight) of water to vermicultite. I keep it at about 1:3 during most of the incubation and during the last few weeks, let it dry out to 1:4. I determine the change in water ratio by weighing the egg containers. I have let them dry out to 1:7 with no denting of the eggs. Last year I had 100% of the fertile eggs hatch.
Gaylon Holmes - Thank you

Mattmorelia - Mark, in reguards to the DNA sex determination test. What is a confidence level to date if any? I have heard a DNA method is being (attempted to be) employed by some people to sex baby tortoises/turtles. Is there any truth to this?
Dr. Mark Seward - We are in the latter stages of development of the test. At this point it appears to be 99% accurate. However, further testing needs to be done. DNA sex determination shouldn't work with any species that has temperature dependent sex determination. It needs to have genetically determined sex. It should be possible to develop a test for any genetically determined species.

Jim Elliott - s> I want to keep a pair of gilas in the future Mark> what advise can you give me for someone keeping gilas for the first time> set up and husbandary
Dr. Mark Seward - Husbandry is very easy and straight forward for Gilas. Ideal temperature gradient of 77-85 degs. Feeding should never be a problem. Hatchlings eats small fuzzy mice. I feed them about every four days. Adults should be fed every 7-14 days. I try not to keep excess weight on my adults. Lighting is not important. Ideal cage size for an adult is about 5 sq ft of floor space.

REP - Mark, what do you see for the future of Glias? (repopulation, captive breed price, reputation)
Dr. Mark Seward - I'll answer your question the best I can. If I missed your meaning, let me know. There is always a problem supplying the demand for Gilas. I see the market for them only increasing over time. Although they are venomous, they are certainly not dangerous. I think they will continue to have wide appeal. Until more people working with Gilas do a more consistant job producing them, the price will remain high. There are good populations of Gilas in the wild.

st - I was told by Vita Tech in Canada that the DNA testing for the Heloderma was not completely accurate in the past. Has something improved recently?
Dr. Mark Seward - Early versions of the test were not consistantly accurate. We are on about the 5th generation of the probe at this time. Final testing will only determine how accurate.

t-rick - There were reports of an albino Gila,back in the 50's or 60's,I think. Have you heard of any being collected or bred?
Dr. Mark Seward - I am aware of a T+ as well as a T- Gila in captivity.

varanid - because of the aggressive nature of the males during breeding times how do you go about insuring that the females get bred? Are there compatibility issues between the sexes?
Dr. Mark Seward - Male aggression is not a problem for me because I don't let the males in cantact with one another. I have heard others state that they have observed compatability issues between certain male-female pairs, but I have not experienced this.

retic - alright ,how old are gilas when they sexually mature, and are there first clutches usually bad but there later clutches good?
Dr. Mark Seward - Like most reptiles the onset of maturity depends on a lot of factors
retic - ideal conditions
Dr. Mark Seward - If they are fed small, frequent meals (the frequency is the key), Gilas will grow very quickly. The first chance I would hope for a successful breeding is the season after there second year, More consistantly, though, after their 3rd year. They can produce small numbers of infertile eggsif they are too young.

Zeratul - What is the current state of wild populations? How much of a problem is illegal collecting?

Dr. Mark Seward - Population numbers in the wild are very difficult to quess. Gilas spend 99% of their time under the ground. Poaching is a problem. Some of the animals I am getting from the AZ-Sonora Desert Museum are from a group confiscated being smuggled in from Mexico. Two defendants are currently waiting trial for that one.

Jeff Barringer - ...ok my turn..... Mark no question... I just want to say you have a great page.... I like the fact that it goes out of the way to provide good herp content
Dr. Mark Seward - Thanks Jeff. I have had a lot of fun with it. I have a lot of ideas for what I want to add to it, but there is not enough time in a day.

John Hollister - What are the primary behavioral differences between the sexes in captivity? and what is the URL for your page?
Dr. Mark Seward - The URL is There are no differences in the behaviour of the sexes until they interact with on another. Gilas certainly don't have any problem telling male from female. If you have a known male, he will act accressively towards other males, but will react with a lot of tongue flicking, etc. towards females. Having a known male is important in interpreting the reaction, because females will also fight females on occasion. Gordon Schuett at the U of AZ is starting a study to look at female-female combat.
John Hollister - thanks

Adam Johnson - what do you think on the validity of cinctum to suspectum? I have seen these species breed together naturaly in the wild, along with spotted patterns as well..about the albino gila there has been several caught, also other types such as hypo and melanistic and patternless.i, have also seen them kill each other in capt.
Dr. Mark Seward - There is no question that both subspecies interbreed. The change from the typical reticulated appearance to the Banded happens gradually from south to north. That is, northern suspectum have characteristics of cinctum and southern cinctum have characteristics of suspectum. The question about whether the subspecies is valid is more than I want to get into. Subspecies classification is a completely man made attempt to classify animals. The animals don't know the difference.
Adam Johnson - thank you mr.seward

amazoa - Does it require a venomous permit to keep Gilas and Beaded Lizards? You said earlier "their not to dangerous", so what I've seen printed on the effects on the respiratory system would be just an occasional allergic reaction . Not a major concern? What substrate do you use in your enclosures since they burrow so much?
Dr. Mark Seward - They are venomous and their bite should be considered a medical emergency. However, nobody has ever died from a Gila bite. They should be handled carefully and one should never put him/herself in a position where a bite could occur.
Dr. Mark Seward - I use chipped aspen (Sani-chips).
amazoa - permit?
Dr. Mark Seward - Sorry. That depend on your state and local regulations. In some states, they are prohibited. In Colorado, where I am, they are not regulated. I understand that in FL a venous permit is required.

b13 - how many babies do you sell of the breeding stock, and how many do you keep from breeding
Dr. Mark Seward - This last fall I held back 3 animals.

BlkRN - What were the major hurdles is getting these to breed in captivity?Do you work with beadeds as well? and lastly, what are the morphological differences between the subspecies of Gila's?
Dr. Mark Seward - I don't currently work with Beadeds. Both subspecies look the same as hatchlings. That is they are both banded. The major hurdle was to hold suspect anything anybody said or wrote about breeding them. There is a lot of misinformation out there. For me it was important to figure out to keep the males apart.. Then how to handle the eggs. I spell out what I am doing pretty clearly in an article in the DEC issue of Reptiles.

boidguy - along with temp. do you also cycle humidity durring the beeding season? and what kind of humidity cycle??
Dr. Mark Seward - I previously lived in Maryland (a lot more humid) at sea level. Now I am in Colorado at 7200 ft. and a lot drier. No difference in the breeding.

Kevin Thompson - I live in AZ, and is it legal to collect Gilas from the wild, or are they endangered and protected?
Dr. Mark Seward - They are protected in every state in the US and in Mexico and cannot be collected without a scientific permit.

Jeff Barringer - Dr.Mark Seward I would like to thank you for being our guest tonight... I certainly enjoyed it and would like to have you back as a guest in the future
Dr. Mark Seward - I have really enjoyed it and would love to come back sometime. If anyone has any other questions feel free to contact me
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