Trees will appear "hot" in the evening but at least you can see them, a possum at this time of year should stand out like all hell.
Mornings are best for thermals when ambient and ground/foliage temps have dropped...makes defining the background more difficult but life sticks out better....same for rain 12hours steady rain makes everything the same temp.....except the animals which stick out like a sore sticking out thing but you cant see any background as it is all the same temp.
IMO it should be used as a spotting aid
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