The most common and widespread hummingbird in the sunny, open areas of Costa Rica, such as in parks, suburban gardens, coffee plantations, and in other non-forested areas, is the Rufous-tailed Hummingbird (Amazilia tzacatl).

Rufous-tailed Hummingbirds are mostly iridescent green in color but get their common name from their contrasting rufous tails. These medium-sized hummingbirds have red bills and green gorgets. The sexes are similar, but the males have more green iridescence and the upper mandible of a female's bill is completely black, while that of a male shows some red.

Rufous-tailed Hummingbirds are highly aggressive and territorial, and they will fiercely guard any favored nectar sources like Heliconia flowers. The males are quite vocal and will sing their high, lisping songs throughout the day near their chosen flowers. These feisty hummingbirds also have various territorial chasing and feeding calls as well.