The Fork-tailed Woodnymph is found east of the Andes from north east Venezuela to northern Argentina but is missing from the extreme south of Brazil. See the distribution map at xeno-canto.

It likes forest and forest edge habitat and is also found in semi-open areas and gardens. It feeds on both nectar and insects.

The bill is black and medium sized but it is variously described as "straight", "essentially straight" or "slightly decurved". This may be a function of the differences between subspecies of which there are 13.

Photo 6 shows an immature male while photo 7 from northern Peru shows a male of the sub-species T. f. viridipectus with a more extensive green gorget extending down to the breast.