Based on what I’ve found on-line, hummingbird experts have only recently figured out how the tongues of these birds operate in gathering nectar or, in the case of our back yard, sugar water. According to an August 2015 article in The Washington Post, “… instead of using vacuum to generate suction – imagine drinking lemonade out of a straw – the system works like a tiny pump, powered by the springiness of the tongue. The bird squashes the tongue flat, and when it springs open, this expansion rapidly pulls the nectar into the grooves in its tongue. It turns out it’s elastic energy – potential mechanical energy stored by the flattening of the tongue – that lets hummingbirds collect nectar much faster than if they relied on capillarity.”… the bird rapidly reshapes its tongue, and that change in tension draws sweet nectar into their mouths.”
A fast shutter speed reveals the astonishing length of the species’ tongue, depicted here in the first three shots. (As best as I can determine, this is a female ruby-throated.)
The one below, after feeding for several seconds, lingered long enough to strike several appealing poses.