That was interesting and I'll go with your suggestion unless someone strongly disagrees and has a credible alternative. I had searched quite a bit but of course immature birds tend to be underrepresented.Search the Internet for pictures of that species. See this page for example: https://www.photobee1blog.com/2012/07/honeycreepers-of-costa-rica/
In Costa Rica they have 2 more honey creepers but only the females of the Green Honey creeper are similar. They don't have the pale supercillium above the eyes, instead they have yellow on the beak, especially on the lower mandible.
Jack
Upvote
0