An actual experiment on bearded dragon preferred body temps

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An actual experiment on bearded dragon preferred body temps

Postby Claudiusx » Sun Aug 25, 2019 6:44 am

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1690065/
Click PDF link on left hand side of site to download and read PDF

It's a study about heart rate in relation to body temperature, and the effect heartrate has on cooling and heating in pogona barbatas.

But of course, a study on temperature and heart rate is going to have good data on body temperatures.

Body temperatures were measured with surgically implanted devices:
(b) Body temperature We measured Tb with surgically implanted, temperature sensitive radio transmitters (Sirtrack, Havelock North, New Zealand). The transmitters were encased in non-reactive epoxy resin and weighed 10^15g, depending on the size of the battery . They were implanted into the peritoneal cavity of locally anaesthetized lizards (using Lignomav) and all animals healed well. The transmitters were calibrated in a temperature-controlled water bath and were accurate to 0.18C. Tb was determined by measuring the temperature-dependent intervals between two transmitter pulses with either a digital processor (Telonics, Pasadena, USA) connected to the telemetry receiver (Telonics TR2, Pasadena, USA) or using a remote sampling system described by Grigg et al. (1992). We measured Tb every 5^10min during the day (07.30^17.30) and every 20^30min at night.


The whole study is a very interesting study, I highly suggest reading it. But for the purpose of this topic, body temperatures, that is what we will be discussing.

We chose 40C as the ceiling for Tb during heating because lizards tolerate a Tb of 40C but seemed to try and actively cool at a higher Tb (see}3).

Based off of their data, and their analysis and monitoring of heart rate, the pogonas didn't actively try to cool down until OVER a body temperature of 40c. Do note that heart rate seemed to substantially increase once the dragons crossed the 40c body temperature range. But this is a beneficial feature of cold blooded creatures, the ability to raise heartrate to help cool/heat the body. It's like the radiator fan in your car running quicker when it gets to a certain temperature.

When Tb reached between 35 and 40C, lizards started shuttling between sun and shade and Tb remained relatively stable in the mid to high 30Cs (rarely over 40C) until late afternoon.

They don't give exact numbers here, but mid to high 30's is clearly 35-39/40c.

Once again, they came to a scientific conclusion that most of their study lizards didn't try to cool off until body temps of 40c. This was observed both behaviorally, and by heart rate and hysteresis.
we describe as reverse hysteresis, in which heart rate during cooling exceeded heart rate during heating.This occurred when animals got very hot, near 40C, possibly in an attempt to avoid further heating (reduced heart rate) and upon entering a cooling environment to dump heat (increased heart rate). We think that the demonstration of reverse hysteresis by animals warmer than their `set point'Tb provides further support for the validity of the functional explanation of changes in thermal conductance.

[Click image to enlarge]


You can see from the chart here (it's only a chart of 3 of their sample pogonas) that they all basked at one point in the day to near 40c, or above it in 2 of the dragons cases. It looks like dragon 2 reached 45c, and dragon 3 reached 42-43c.

Not really on topic, but it's interesting to note how the pogonas heart rate (as visible in the chart) shows that the heart rate stays relatively stable while heating (slight increases) but drastically spikes once the dragon decides it want's to cool down. This is how the scientists were able to come to an actual scientific conclusion on what exactly each dragons preferred body temperature was.

-Brandon
Follow along with all my beardies. Check out my thread here!: Claud's Crew
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Re: An actual experiment on bearded dragon preferred body te

Postby CooperDragon » Mon Aug 26, 2019 9:09 am

Interesting to know what's going on "behind the scenes". What I've observed supports offering a range of temps. What I've read shows that the range tends to vary a bit depending on individual preference.
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Re: An actual experiment on bearded dragon preferred body te

Postby Claudiusx » Mon Aug 26, 2019 10:21 am

I agree. And the study definitely shows that different dragons had different temp preferences. They make a comment that there was a difference of 6c between the one that cooled off at the lowest and the one who cooled off at the highest.

But I think anyone who has raised multiple dragons knows this to be the case too. Naughtica would refuse to bask if her basking surface wasnt exactly 98. Kiki on the other hand liked 105 for her whole life.

I think learning your dragon is the best you can do.

But It definitely negates the comment that providing over 40c (104f) in your tank is going to kill your dragon.....

I agree with you, providing a range for them to pick from is best. They know what they want. And we can make adjustments as they start to show us that.

-Brandon
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Re: An actual experiment on bearded dragon preferred body te

Postby MrSpectrum » Sun Sep 01, 2019 6:19 am

CooperDragon wrote:What I've read shows that the range tends to vary a bit depending on individual preference.

claudiusx wrote:I agree. And the study definitely shows that different dragons had different temp preferences.

Sorry guys, I get this strange little picture in my head of a wild beardie in the Outback, packing his little beardie bags and moving because he doesn't like the local climate... :lol:
(Yes, like Yossarian in Catch-22, I'm a very weird person...) :roll:
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Re: An actual experiment on bearded dragon preferred body te

Postby CooperDragon » Sun Sep 01, 2019 8:11 am

I've had the same image except it's one of the hobo bags tied to the end of a stick as they walk away toward the horizon.
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