Wild Polar bears and Sun bears live in parts of the world where living conditions can be considered extreme. Polar bears lives in Northern Arctic regions, where temperatures are often well below zero Celsius for the majority of the year. The Sun bear lives in tropical Southeast Asia with average temperatures of around 28 degrees above zero and almost 100% humidity. Both bear species are threatened in the wild by climate change and destruction of their habitat.

Polar bears and Sun bears are kept in many zoos around the world. Bears in captivity are exposed to different outside temperatures than they are ‘build for’ and used to all year round in the wild. In captivity, the upper temperature limit of Polar bears and the lower temperature limit of Sun bears are often exceeded. Until now, the effects of this on the species’ metabolisms have hardly been investigated.

This study by the University of Köln, funded by Bears in Mind between 2010-2012, looked into which behavioural and autonomic mechanisms for thermoregulation are available for the respective species, to examine to which degree behavioural regulation complement physiological mechanisms to minimise energy expenditure, and to determine the range of the thermoneutral zone for the respective species. The study took place in several European zoos during summer and winter conditions.