Hummingbirds eat little else, and the Sword-billed Hummingbird's beak is the longest of any bird in relation to its body.

Katie Lee shows a sword-billed hummingbird reaching deep inside the trumpet-shaped blossom of a Burgmansia sanguinea.

Some species, especially those with unusual bill shapes such as the Sword-billed Hummingbird and the sicklebills, are co-evolved with a small number of flower species.

The bill of all birds providing 30 to 50% of its body surface area, although another Neotropical species, the Sword-billed Hummingbird, has a longer bill relative to its body length.

Another size champion among hummingbirds is the Sword-billed Hummingbird, a fairly large species in which about half of its 21 cm (8.3 in) length is from its bill (easily the largest bill-to-body-size ratio of any bird).

The Sword-billed Hummingbird (Ensifera ensifera) with its immensely elongated bill has co-evolved with certain passion flowers, such as P. mixta.