Diets of puffbirds and mortality sources of adult hummingbirds are poorly known. I observed a White-necked Puffbird (Malacoptila macrorhynchus) attack and capture a Rufous-tailed Hummingbird (Amazilia tzacatl) in the Republic of Panama. This is the first report of birds as prey of puffbirds and identifies another source of natural mortality for hummingbirds.