Titmice turn on the central heating

• Small birds are hot creatures with an average body temperature of 40° Centigrade, and so must burn energy at a formidable rate to stay warm. This becomes quite the challenge in winter when birds are 40-50 degrees warmer than outside for extended periods, even in comparatively mild regions such as Scotland. Thus, the little bird in winter must spend most of the day either feeding or searching for food. In fact, on a cold winter day a small passerine like a Great Tit may gain as much as 10% of its own body mass as fat just to last through the long night. For an average Scotsman this means adding some 8 kg of butter to the body every day – and burn it all overnight! This is certainly not an easy task during a short, rainy winter day.Once the bird has found a peanut or a spider to feast on, the nutrients in the food must be converted into a form that can be utilised by the different physiological systems that keeps it warm. The key player in this equation is the mitochondrion – a tiny organelle that resides inside the cells themselves. The mitochondrion is the engine of the bird’s body and works by building up potential energy that drives the production of molecules called Adenosine Triphosphate (ATP) which in turn are used to fuel every working part of the body. The process is similar to how a hydroelectric dam functions. Because a small bird in winter needs to work much harder to stay warm when it is colder outside, one could imagine that the mitochondrion should help out by creating more energy-rich ATP when autumn turns to winter. A recent study suggests that this need not be true.A group of researchers from Scotland and Sweden followed Coal, Blue and Great Tits along the shores of Loch Lomond outside Rowardennan from autumn to winter. The team collected small blood samples from the birds as they visited feeders in the forest and studied how the function of the mitochondria changed between the seasons. They were greatly surprised to learn that instead of aiding the birds by producing more energy for bodily uses (including keeping warm), the blood mitochondria themselves became more heat generating in winter. This means that Scottish tits may have a central heating system installed, allowing them to conveniently turn up the thermostat a few notches when air temperature drops! The team is now working to understand the finer details of what is driving this remarkably unexpected response.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Zoology (hsv//eng)

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