HELLO!!

Thermoregulation is energetically expensive for many organisms,specially for small animals like birds,shrews.we know that heat gain or heat loss is the function of surface area.Since these small animals have larger surface as compares to there volume they lose body heat very fast during  exposure to cold environment.To maintain their metabolism they have to expend much energy to keep their body warmer that much energy a small creature could not afford and thus they simply conform.

THANK YOU!!