The size of the perch should match the approximate diameter of the body. A hatchling for instance would do fine on a plastic coat hanger while an adult might need a branch of a couple of inches around. I ended up placing a third perch about 8" below the heat panel and that's where I also place my probe. She also has two other perches that crisscross about 12" below the panel so she has thermal gradients at all the levels. She generally chooses right below the panel when she's just eaten or is nearing shed and the highest perch far from the heat source during the day. The rest of the time, she just crawls around all the levels and usually hangs near the door nearest the heat....evidently hoping that a mouse will fall in the door accidently!

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1.0~amel corn~C.S.
1.3~Aztec Okeetee corns~Coatl,Maya,Acatl,Tepin
0.1.1~Green tree python~Tempest, Whisper
0.2~Rhodesian Ridgebacks~Akilah, Ona
0.1~Old black Lab~ Callie (RIP)
2.0~fat cats~Topper, Briscoe
3.0~Horses~Zaarah,Galliano,Achilles.....
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