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Yellow-margined Flycatcher - BirdForum Opus

Alternative names: Zimmer's Flatbill, Yellow-margined Flatbill

Tolmomyias assimilis

Includes Sucunduri Flycatcher; notice that Yellow-winged Flycatcher of Central America and areas west of the Andes is no longer included.


13–13·5 cm (5-5¼ in)
Typical overall appearance of a relatively large-headed flycatcher, with pale greenish and yellow plumage contrasting with darker wings. Diagnostic features are: dark brown iris (but may be grey), bright yellow outer edges to flight feathers with no wing bars.

  • Crown, side of head and mantle grey with olive wash
  • Upperside olive-green
  • Wings dusky with yellow margins on flight feathers and greater coverts. May give hint of wing bar
  • White speculum at base of primaries not always obvious
  • Throat pale grey
  • Breast and flanks pale olive
  • Belly yellowish

Similar Species

Yellow-Olive Flycatcher lacks white at the base of primaries; Gray-crowned Flycatcher has a greyer crown more clearly contrasting to upperside;, or Slaty-capped Flycatcher.


South America: east of the Andes in Colombia, Ecuador, Peru, Bolivia, Brazil, French Guiana, Guyana, Suriname, and Venezuela.


Yellow-winged Flycatcher was formerly included within this species.


Eight subspecies are recognized[1]:

  • T. a. neglectus:
  • Eastern Colombia to south-western Venezuela and north-western Amazonian Brazil
  • T. a. examinatus:
  • South-eastern Venezuela to the Guianas and north-eastern Brazil (Pará and Amapá)
  • T. a. obscuriceps:
  • South-eastern Colombia (Meta) to north-eastern Ecuador and north-eastern Peru (eastern Loreto)
  • T. a. clarus:
  • Peru immediately north of Río Marañón south to northern Puno
  • T. a. assimilis:
  • Central Brazil, south of the Amazon, east to the Canumã/Sucunduri rivers
  • T. a. paraensis:
  • North-eastern Brazil (eastern Pará and north-western Maranhão)
  • T. a. calamae:
  • Tropical northern Bolivia and south-western Brazil (south-eastern Amazonas)
  • T. a. sucunduri:
  • South central Amazonian Brazil, between the Canumã/Sucunduri rivers and the lower Tapajós River

The first seven subspecies are from east of the Andes in South America. The last one, sucunduri, was originally described as full species but is now included here.


Subtropical lower foothill forests and marshy areas.



Forages in middle and upper levels of rain forest. Their diet consists of insects, particularly beetles; also ants and other bugs. They also eat fruit occasionally.


  1. Clements, J. F., T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, S. M. Billerman, B. L. Sullivan, and C. L. Wood. 2022. The eBird/Clements checklist of Birds of the World: v2022. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/
  2. Gill, F, D Donsker, and P Rasmussen (Eds). 2023. IOC World Bird List (v 13.1)_red. Doi 10.14344/IOC.ML.13.1. http://www.worldbirdnames.org/
  3. del Hoyo, J., I. Caballero, G. M. Kirwan, N. Collar, and P. F. D. Boesman (2022). Yellow-margined Flycatcher (Tolmomyias assimilis), version 1.1. In Birds of the World (B. K. Keeney, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.yemfly1.01.1

Recommended Citation

External Links

GSearch checked for 2020 platform.1