Biological Miracle – Wood Frog

A great book about how animals survive super cold winters is "Winter World" by Bernd Heinrich.

Bernd is a super fascinating biologist who really dives deep in to things. At one point in the book I think he was talking about chipmunks surviving winter, and it goes really fun on the first principles. Something like: "chipmunks have a surface area of X m^2, and need to maintain an internal temperature of Y˚C. If the outside temperature is -40˚C they therefore they need to consume Z calories per hour just to maintain body temperature. Their favorite food are pine nuts from the white pine tree. The pine nuts each have B calories, so the chipmunk will need to eat D of them per hour. How many nuts can a chipmunk fit in its mouth? Well I found a dead one and shoved pine nuts in to its mouth until I couldn't fit anymore, and managed to get 17 in there. That means..."

"Well I found a dead one and shoved pine nuts in to its mouth until I couldn't fit anymore, and managed to get 17 in there."

That part is .. weird. What is the point except morbid humor?

Chipmunks have a food storage, so they don't store nuts in their mouth. They wake up, go to the food storage and eat and go back to sleep. They don't go outside to collect more nuts in -40°C. Maybe that was the point of that calculation, to show it would not be a good strategy, but there ain't much nuts in winter on trees left anyway.

(and the calculation above lacks insulation of the fur and their sleeping place)

The number of seeds that fit into a cheek pouch determines calories transferred per trip to storage.

Knowing this number will be critical for any modelling of chipmunk energetics.