Hmm. Good thought, but I don't think that's the case - It was definitely warm. They get thawed in hot water until they're soft all the way through, then warmed under the ceramic bulb on the tank screen lid.

At least with mice, he's never cared how hot they are. I've offered one once even feeling cool straight after thawing, with no extra warming, and he'll snap them up and chow them down (of course, most of the time I make sure they're nice and mouse-temperatured, I was in a hurry that day!) The first time I had that same thought, as he coiled it in his water and definitely killed any warmth it had, but before offering it again I would re-warm it under the ceramic bulb.

He also would go up to the lid and try to strike at the mouse that was sitting on top, which hadn't been warmed at all after the first time (when I warmed to scent the tank) and was cooler than the rat.

Not opposed to putting extra focus on the warming next time though! I'll have to borrow a hair drier and see if that works better than the heating bulb.