GEOMETRICAL ASPECTS OF THE ENERGETIC EFFECTIVENESS OF HUDDLING IN SMALL MAMMALS

Reduced energy expenditure resulting from huddling in small mammals is mainly attributed to the reduced surface area/volume ratio of the hud dling group. Here we propose a model to account for the reduction of t he relative exposed area of grouped animals and for the diminution of metabolic rate during huddling. We attempt to explain mechanistically how changes in energy savings may operate. We applied our model to res ults obtained by grouping deformable bodies, and also laboratory measu rements of oxygen consumption on huddling small mammals of four specie s, We found a small amount of diversity in the energetic efficiency of huddling. We estimate that the average relative area lost during hudd ling ranged between 28.7 and 39.1%. The average huddling effectiveness in the studied species was 42%, which is a significant fraction of th e energy/matter budget of a small mammal, especially under winter cond itions.