Heat control for hummingbirds reported in BBC News and Royal Society Open Science doi: 10.1098/rsos.150598, 16 December 2015. Hummingbirds are known for their very high wingbeat, which can be up to 70 times per second when they are hovering. All this activity generates a lot of heat, which must be dissipated or the bird will overheat. Birds’ feathers form very efficient insulators, and keep body heat in, so they must have some way to let heat out when necessary.
Donald Powers of George Fox University, Oregon, USA, and colleagues studied flying hummingbirds with a thermal camera and particle image velocimetry to test the effects of flight speed on heat loss from specific body regions. They found the birds shed heat from around their eyes, shoulder regions and feet. During hovering the birds dangled their feet, which enhanced the heat loss. Using their measurements the scientists concluded “that hummingbirds actively alter routes of heat dissipation as a function of flight speed.”
Donald Powers explained, “As flight power requirement increases- it is highest when hummingbirds hover – the amount of heat generated increases. But these ‘windows’ are sufficient at moderate temperatures to dissipate all excess heat across the full range of flight speeds in hummingbirds.”
Editorial Comment: This is a reminder that flying involves more than a powerful engine (muscles) and the right aerodynamic surfaces. A good understanding of the whole functioning creature is needed. Small creatures like birds need good thermoregulation as they lose heat easily when they are resting, but their intense activity produces enormous amounts of heat, which is equally hazardous. Therefore, getting the right balance of insulation and heat dissipating sites is important, and hummingbirds would not survive unless they already had it right, before they tried to hover. (Ref, ornithology, thermoregulation, flight, design)
Evidence News vol. 16, No. 1
20 January 2016
Creation Research Australia