discussion / Sensors  / 7 April 2021

Spotting primates w/ thermal scope

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Hi thermal experts!
We're thinking here in FFI of getting a thermal scope to help us more accurately count gibbon group size (a key vulnerability in our population estimates).

Any advice or experiences to share using thermal in primate surveys? Any models to recommend, or specs to look for?

I’m specifically wondering if we might be able to spot gibbons looking down on the canopy from atop limestone pinnacles - they are typically 100-300 m from us when we spot them. You can see what that looks like here: https://twitter.com/olliewearn/status/1200451721492750343?s=20

thanks

ollie

cc @montanamud !




Hi Ollie,

I may have some recommendations. For clarification, are you looking for something handheld that you simply look through (as with binoculars or a telescope), something that would record images (like a camera trap), or something mounted on a drone for mobility?

 

Would work best earlier in the morning before the sun heats up the canopy.  Maybe also after a rain.   But we had problems looking down on a hot sunny canopy.  more here https://www.tandfonline.com/doi/abs/10.1080/01431161.2018.1523580?journalCode=tres20

Ollie,

In general, I think it will be very difficult to spot Gibbons at those distances outdoors and under the canopy with a thermal sensor.

The only scopes I know that have a chance of spotting the Gibbons are the FLIR Handheld Optics line. You can choose the thermal sensor and lens on most of the scopes. The higher resolution 640 x 480 sensor will work better under your conditions and distances. Getting a higher mm lens will help a lot with distance as well. FLIR lists a distance at which you can spot a man with their scope, but it will be under perfect conditions. The dense foliage and bright sunlight make your conditions far less than ideal, so go for the scope that lists a distance far more than you need to see (1000m).

Good luck!

 

 

You are exactly right. The longer focal length of the Pulsar gives it a higher native magnification and so it will pick up on heat signatures from further way. A longer focal length typically gives you a longer detection range if everything else is equal.

"Detection range" is basically stating how far away an average size human would cause a signle pixel of the sensor to display the slightest heat signature. So in your viewfinder, you would see a faint speck of white. You would be no means be able to identify the object as a human, primate, vehicle, etc.

One other factor you could consider is the ability to swap batteries in field. The Helion has this ability; the Scion does not. However, a stand alone battery pack and USB cable can negate this limitation. Two important things to note on thermal optics: 1) they cannot see through foliage and 2) they cannot see throuh windows or glass.