There are quite a few species of humming bird living in Manu, including the wonderfully named amethyst woodstar, the black-eared fairy, and the golden tailed sapphire, and absolutely everything about them is extraordinary.
They are tiny (the smallest bird in the world is a type of hummingbird) and some can weigh as little as a 4g, but, in contrast, they are also incredibly fast, flying at up to 55km/h. Hummingbirds are also very agile. They are able to hover in place by beating their wings up to 80 times per second they are also the only type of bird that is able to fly backwards.
Finally they are just plain beautiful to look at. Here are some you might see in Manu: