Some hummingbirds are no larger than a thumb, and the smallest among them are the very smallest birds in existence. Yet it’s hard to avoid superlatives when talking about these tiny creatures. With their often magnificent jewel-like colors, they glimmer like finely wrought works of art. In fact, they are miracles of nature: extremely agile, fast-moving animals that take the characteristics of birds to their utmost limit. Combining dynamism, fragility, and a surprising degree of fearlessness, hummingbirds can be found in the most diverse environments: in tiny front yards in North, Central, and South American cities; on the high plateau of the Andes; and in the dense Amazon forests.