One for all and all for one: the energetic benefits of huddling in endotherms
Article first published online: 21 DEC 2009
© 2009 The Authors. Journal compilation © 2009 Cambridge Philosophical Society
Volume 85, Issue 3, pages 545–569, August 2010
How to Cite
Gilbert, C., McCafferty, D., Le Maho, Y., Martrette, J.-M., Giroud, S., Blanc, S. and Ancel, A. (2010), One for all and all for one: the energetic benefits of huddling in endotherms. Biological Reviews, 85: 545–569. doi: 10.1111/j.1469-185X.2009.00115.x
- Issue published online: 8 JUL 2010
- Article first published online: 21 DEC 2009
- (Received 09 December 2008; revised 12 November 2009; accepted 17 November 2009)
- social behaviour;
- energy conservation;
- ambient temperature;
Huddling can be defined as “an active and close aggregation of animals”. It is a cooperative group behaviour, permitting individuals involved in social thermoregulation to minimize heat loss and thereby lower their energy expenditure, and possibly allowing them to reallocate the saved energy to other functions such as growth or reproduction. Huddling is especially important in the case of animals faced with high heat loss due to a high surface-to-volume ratio, poor insulation, or living in cold environments. Although numerous experimental studies have focused on the huddling behaviour of a wide range of species, to our knowledge, this is the first attempt to review the various implications of this widely used behavioural strategy.
Huddling allows individuals to maximise energy savings by (1) decreasing their cold-exposed body surface area, (2) reducing their heat loss through warming of ambient temperatures surrounding the group, and (3) eventually lowering their body temperature through physiological processes. Huddling provides substantial energy savings and is estimated to reduce energy expenditure by between 6 and 53%. Broad variations in the energetic benefits of huddling depend on the number of individuals and species involved in huddles, the ambient temperatures to which individuals are exposed and the density of the aggregations. It has been shown that huddling individuals have increased survival, a lower food intake, a decreased body mass loss, increased growth rate, reduced water loss, and/or a more constant body temperature together with a significant reduction in metabolic rate. Though huddling has been studied widely, this review reveals the intricacies of this adaptive behaviour.