Analysis of wild tortoise (Testudo graeca graeca)
temperatures using thermal imaging
Two images are taken simultaneously, a high resolution
thermal image (320 x 240) and a visible light image.
These can be 'overlaid' and blended to produce a
variable transparency composite which can help with
The images shown here are at far lower resolution than
actually generated, and the images are only a small part of
what is captured.
Most of the information is 'hidden' in the files generated and
this can then be analysed in specialist software in various
ways to reveal in
great detail what is going on. For example, here we have a
wild tortoise that was observed grazing. The IR images reveal
even heating pattern typical of reptiles after solar basking.
The heat is not concentrated in the surface tissues, but
infuses the entire body. This
is a characteristic property of WiRa radiation as occurs
naturally in sunlight.
It is most obvious here, in the neck/shoulder area. An area of
high blood flow and which is also indicative of core
(the blue line over the head is a cooler stalk of vegetation)
It can be useful to analyse small segments of the image. This
can reveal the degree of solar gain over surface/ambient
and can also generate max-min-average figures for various body
We can also look at one particular body part in detail. Here,
the underside, or plastron. One question that is often asked
"How does the plastron get warm? From contact with warm
substrate or via the carapace/limbs when basking?"
Careful analysis of a series of IR images provides an answer.
During basking phases the prime source of plastron heat is
from the body, with only a small influence as result of
contact or reflected thermal radiation from the surroundings.
One thing that
we have learned is that tortoises are incredibly efficient
'solar collectors' capable of very significantly raising their
above ambient, even in overcast conditions. They also use
their limbs (and extended neck) to direct solar energy right
into the bloodstream,
functioning as a very effective 'heat pump'. This almost
certainly has important implications for the vitamin D3
Heat distribution in plastron zone:
All images (C) 2014 Tortoise Trust