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At the weekend I was on the coast & enjoyed seeing several Goldcrests. At 5g, these are the smallest European #birds & their arrival in autumn from Scandinavia or even further afield seems like a miracle of migration. So much so that their traditional Yorkshire coast name is Woodcock Pilot, possible because they arrive on the coast at the same time as Woodcock but are so small they must have hitched a ride across the North Sea! https://www.yorkshirepost.co.uk/news/environment/country-coast-nickname-for-tiny-winged-wonders-could-be-fanciful-1783461 1/N
pic f.c.franklin flickr CC BY-SA 2.0
While this is a myth, it is still astonishing that a bird so small has the energy to migrate so far. Most #birds have a body temperature of ~41°C and the smaller animals are the more surface area per gram of body they have, meaning small animals loose heat fast. For goldcrests over wintering in Northern Europe this can be extreme: at -25°C their metabolic rate must be 5x the resting rate! https://link.springer.com/article/10.1007/BF01644486 2/4
Pic Sergey Yeliseev flickr CC BY-NC-ND 2.0 DEED
A brisk walk probably raises our metabolic rates by about 5x, so while relatively modest, maintaining this increase overnight requires 1.3 g of fat, 20% extra mass than the bird’s lean weight. The ability of birds to put on that weight each day, and then burn the fat without getting heart disease, is of considerable interest to obesity researchers.
https://onlinelibrary.wiley.com/doi/full/10.1111/j.0908-8857.2004.03378.x and their ability seems to be underpinned by the lack of carbohydrates.
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Pic Steve Herring flickr CC BY-NC-ND 2.0 DEED
Low carbohydrate, but high fat and moderate protein is the basis for the ‘Keto Diet’ that is used medically to treat drug-resistent epilepsy, and suggests that the adverse effects of obesity may be in part mediated by carbohydrates. Surprisingly, the metabolic effects of only consuming fats are remarkably similar to the effects of starvation and birds like the Goldcrest give us a great model for studying these processes. https://onlinelibrary.wiley.com/doi/full/10.1111/j.0908-8857.2004.03378.x 4/4
Pic Steve Herring flickr CC BY-NC-ND 2.0 DEED
