probably something like this: https://www.amazon.de/Parrot-Wärmebild-Drohne-Hochpräzisions-Wärmebildkamera-Fachkräfte/dp/B07RYBD86M/
but I hoped for something cheaper.
Flir makes good IR sensors and their products range from cheap low-res to... awesome. They have a nice option combining thermal imaging and normal sensor so you overlay thermal data (low res) on a higher resolution image.
Btw I am not sure of your use case but you may find this interesting: https://www.researchgate.net/publication/232778761_Tracking_bee_with_harmonic_radar
It is a passive system (no battery, no emission) and requires no drone ;)
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