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Number of species: 72

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Red-eyed Vireo - Vireo olivaceus

HY and some SY Red-eyed Vireos can generally be recognized easily by eye colour, but feather differences are more subtle by age than for many other species. While some SY and ASY individuals can be separated as late as September by the condition of the primary coverts, rectrices, and tertials, there are many intermediates throughout spring and summer that are not reliably aged. Determination of sex is limited to brood patch / cloacal protuberance during the breeding season.

Quick Tips:

  • In fall, check the iris colour - it is grayish-brown on HY birds, and red on AHY birds; this typically is only reliable until around March, but some SY birds may retain a brownish eye longer and can be identified in this manner.
  • Examine the shape of the primary coverts and rectrices - on HY/SY birds, both are relatively narrow and pointed (and faded by spring/summer), while on AHY/ASY birds, both are broad and rounded (and relatively fresh in spring/summer).
  • In fall, examine the upper mandible lining - it is pinkish-gray to white on HY birds, and dark gray on AHY birds; note that this is only reliable from summer through February, though some SY birds may retain pale colour longer and can be identified in this manner.
  • In spring, look for a molt limit between the tertials and secondaries - on SY birds there is often a cline of wear throughout the secondaries and tertials, while on ASY birds the tertials may be similarly pale, contrasting with uniformly darker middle secondaries.

Species account prepared by McGill Bird Observatory

Click on any image below to bring up the side-by-side comparison tool.
Age / Sex  Image sets 
Hatch year / Unknown
Iris grayish to brownish; primary coverts and rectrices somewhat narrow and pointed, roof of mouth pinkish to pale gray.
Thumbnail - MG2-1851-64446-Vireo_olivaceus_AOU_7_52-3717.jpg Thumbnail - MG2-1851-64446-Vireo_olivaceus_AOU_7_52-3715.jpg Thumbnail - MG2-1851-64446-Vireo_olivaceus_AOU_7_52-3716.jpg
After hatch year / Unknown
Iris generally red; primary coverts and rectrices rather broad and rounded; roof of mouth dark gray.
Thumbnail - MG2-2000-07588-Vireo_olivaceus_AOU_7_52-3723.jpg Thumbnail - MG2-2000-07588-Vireo_olivaceus_AOU_7_52-3721.jpg Thumbnail - MG2-2000-07588-Vireo_olivaceus_AOU_7_52-3722.jpg

Additional age / sex class descriptions

The following additional age / sex class descriptions were found for this species:
Age / Sex   Age / Sex class description
Second year / Unknown Primary coverts and rectrices somewhat narrow and pointed; iris sometimes brownish.
Juvenile / Unknown Brownish-green above and whitish below, with wing bars; iris brown or gray-brown.
After second year / Unknown Primary coverts and rectrices rather broad and rounded; sometimes a contrast between paler tertials and uniformly darker secondaries.
Number of species: 72

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