Wild Birds

Yellow-margined Flatbill or Yellow-margined Flycatchers

The Yellow-margined Flatbill or Yellow-margined Flycatchers (Tolmomyias assimilis) is a species of bird in the Tyrannidae family. It is found in humid forests in southern Central America, and the Chocó and Amazon in South America.

There are significant differences between Yellow-margined Flycatchers (notably voice) between the populations east and west of the Andes, leading to suggestions that the two should be regarded as separate species, in which case the population west of the Andes retains the English name Yellow-margined Flatbill (or Flycatcher) but with the scientific name T. flavotectus, while the Amazonian population retains the scientific name T. assimilis but with the English name Zimmer’s Flatbill (or Flycatcher).

Both populations closely resemble the Yellow-olive Flatbill and are typically best separated from that species by voice.


  1. Gill, F., Wright, M. and Donsker, D. (2009). IOC World Bird Names (version 2.2). Available at https://www.worldbirdnames.org/ Accessed 30 August 2009

Gordon Ramel

Gordon is an ecologist with two degrees from Exeter University. He's also a teacher, a poet and the owner of 1,152 books. Oh - and he wrote this website.

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