It is abundantly clear that hummingbirds have an abundance of skills, some of them spectacular. As a result of all of exercising these skills they require a lot of energy. Their flights are often like aerial pilots with their dogfights.
As David Attenborough in his film explained this:
“When flying, hummingbirds have the highest oxygen demands of all vertebrates. Their wings beat as fast as 80 times a second. The problems is getting all that oxygen to the proper place. When the bird is perched its heart beats at around 400 times per minute. In flight it rises to an astonishing 1,200 beats per minute [20 times per second] as the heart pumps oxygen rich blood to the wing muscles. Even this is not enough for hovering, so the heart expands in size so it can pump more blood with each beat. When this happens, the blood circulates around the whole body. Heart to lung, heart to muscles, and back to the heart in under 1 second! They are living at the edge of what is possible. Extreme aerial athletes with extreme needs. It’s no surprise that when they are not flying and feeding, they rest and conserve energy.”
That really is astounding. As a result of all of this, hummingbirds spend 80% of their day perched. That is why I sometimes have such a hard time finding them, as they perch often inside tree branches where it is so dark and difficult to photograph them. During this time, they stretch muscles and groom their very important feathers. They also take advantage of rains to clean their feathers. Unlike insects they really seem to flourish in the rain. I noticed this from inside my cottage this summer when I was watching hummingbirds in the rain.
The hummingbirds also as a result need to protect their sources of nectar. In the forests of South American for example, they must protect their flowers from nectar thieves. That is why they have evolved to drive out competitors. Like all good capitalists they are habituated to destroy the competition. It is in their nature.
As a result of all of these high energy needs, hummingbirds must feed every 15 minutes or more. “Starvation and even death is always only hours away,” Attenborough reported. As a result, they don’t have time to visit flowers that have no nectar. They don’t really have time to chase competitors to away either, but I can report they do. This begs the question, what do they do in the dark?
Staying alive until morning is a challenge for every hummingbird. They do that by going into torpor every night of their lives. This is similar to hibernation. It is like going into hibernation every night! Their heart rate drops precipitously and their heart rate goes down from 400 to 40 beats per minute. That is 1% of the energy they use when flying! This is a radical solution, because while they are in torpor they can’t move and are easy prey for predators that are out and about where they are. They can’t escape from nocturnal predators that find them. If a predator finds them at night, they are dead meat. When day breaks, they shiver and in about half a hour can fly again. It is a remarkable transformation for these truly remarkable birds.
To feed themselves sufficiently hummingbirds must be smart, except when it comes for rivals at least. Then they can be stupid. Competing when it is not necessary to compete. Reminds me of humans.
They must learn to avoid flowers that don’t produce nectar or not enough or are temporarily drained. As a result, they learn to avoid flowers they have already drained of nectar until they are replenished. They must have mental timers in their brains and be able to remember flowers already visited recently in trees or flower patches among enormous numbers of virtually identically coloured flowers. So Hummingbirds are indeed smart. That is why Attenborough said it was “a great feat for a bird brain.”
Hummingbirds can’t live on nectar alone. That is why they have learned to catch prey such as flying insects as well, which of course requires incredible aerial dexterity. They particularly need protein to replace feathers and build muscles.