All that glitters
BBC Wildlife|September 2021
Dazzling in flight and in colour, hummingbirds have long captured our imagination. But these spectacular birds are vulnerable to a changing world.
Jon Dunn
All that glitters
As dawn breaks in a northern wood – one that, at first glance, doesn’t look terribly different to the deciduous woodlands of Britain – a hummingbird is stirring. The spring night here, only a few hundred miles south of the Arctic Circle, has been long and cold. It could have been fatal for a bird that weighs little more than a penny, let alone one with a metabolism as fast and specialised as that of a rufous hummingbird. Hence, he hasn’t just slept; he’s spent the night in a state of torpor.

His heart has slowed from a daytime rate of 1,200 beats per minute to less than 100 beats per minute, which, for a hummingbird, is barely ticking over. His body temperature has dropped too, by some 26°C, to just a few degrees above the chilly ambient air temperature. To put that into perspective, were our body temperature to drop by 2°C, we’d enter a state of hypothermia. To all intents and purposes, this hummingbird is coming out of a state of near hibernation.

Fuel in the tank

Extremes of exertion demand a lot of energy. The recommended daily calorie intake is 2,500 for men and2,000 for women. But if we had the metabolism and energy requirements of a hummingbird, it would increase to approximately 155,000 calories a day. Nectar from flowers is sugar-rich and provides the energy hummingbirds need. They cannot, however, live on sugar alone – they supplement their daily diet with protein in the form of small insects and spiders, which they hunt when not visiting flowers.

Rise and shine

Esta historia es de la edición September 2021 de BBC Wildlife.

Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.

Esta historia es de la edición September 2021 de BBC Wildlife.

Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.