If it's any help, this bird (and the bird pictured on the sign you posted) does not look like an Amazilia; from what I see of pictures online all Amazilias have a much rounder head, a more elongated body shape and a longer bill.
Rufous-throated sapphire should also have a slightly rufous throat, even in females, which this individual clearly lacks.
However, this species also doesn't look a lot like fork-tailed woodnymph. The body shape seems more accurate, but head shape and bill length still don't quite fit... I wonder if anyone with South American bird guides could help?
How many hummingbirds did you see in total? On my visit in August 2016 I only saw one female, which I think was the same individual as the one on this picture, but unsigned at the time so I just identified it as the species zootierliste listed for Avifauna (being fork-tailed woodnymph).
