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Number of species: 80

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Black-throated Blue Warbler - Setophaga caerulescens

Black-throated Blue Warbler is generally an easy species to age and sex, since males and females have distinctly different plumages at all ages, and especially on males the molt limit of HY/SY birds is very readily apparent.  Ageing of females may require closer examination of the wing and/or tail, but can still be done with confidence in most cases.

Quick Tips:

  • Consider the upperparts - on males they are blue and black, and on females they are greenish
  • Examine the primary coverts - on HY/SY birds they are paler and duller than greater coverts and lack edging, while on AHY/ASY birds they are uniform with the greater coverts and have distinct greenish (female) or bluish (male) edging
  • Look at the primaries - on AHY/ASY males there is considerable white extending beyond the primary coverts (7-14 mm), on HY/SY males and AHY/ASY females there is a moderate amount of white (3-11 mm), and on HY/SY females there is little to no white (0-6 mm)
  • Look at the tail - on AHY/ASY males they are relatively broad and rounded with large white patches, on AHY/ASY females they are similar in shape but with indistinct white patches; on HY/SY males they are narrow and pointed with moderate white patches, while on HY/SY females they are similar in shape but have little or no white

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 / Male
Blue and black upperparts with patches of brown or green; brownish primary coverts contrasting with blue-edged greater coverts; moderately extensive white patches on primaries; relatively narrow and pointed rectrices.
Thumbnail - MG2-2500-68109-Setophaga_caerulescens_AOU_7_52-2266.jpg Thumbnail - MG2-2500-68109-Setophaga_caerulescens_AOU_7_52-2268.jpg Thumbnail - MG2-2500-68109-Setophaga_caerulescens_AOU_7_52-2267.jpg
Date: Sep 7
Hatch year / Female
Greenish upperparts; brownish primary coverts contrasting with green-edged greater coverts; white patches on primaries limited or absent; rectrices relatively narrow and pointed, with whitish patches small and indistinct or absent.
Thumbnail - MG2-2440-72242-Setophaga_caerulescens_AOU_7_52-2275.jpg Thumbnail - MG2-2440-72242-Setophaga_caerulescens_AOU_7_52-2277.jpg Thumbnail - MG2-2440-72242-Setophaga_caerulescens_AOU_7_52-2276.jpg
Date: Oct 1
After hatch year / Male
Blue and black upperparts; blue edging to primary coverts; extensive white patches on primaries; relatively broad and rounded rectrices.
Thumbnail - MG2-2440-72112-Setophaga_caerulescens_AOU_7_52-2260.jpg Thumbnail - MG2-2440-72112-Setophaga_caerulescens_AOU_7_52-2262.jpg Thumbnail - MG2-2440-72112-Setophaga_caerulescens_AOU_7_52-2261.jpg
Date: Sep 21
After hatch year / Female
Greenish upperparts; pale greenish edging to primary and greater coverts; moderately extensive white patches on primaries; relatively broad and rounded rectrices with indistinct whitish patches on outer feathers.
Thumbnail - MG2-2440-72208-Setophaga_caerulescens_AOU_7_52-2263.jpg Thumbnail - MG2-2440-72208-Setophaga_caerulescens_AOU_7_52-2265.jpg Thumbnail - MG2-2440-72208-Setophaga_caerulescens_AOU_7_52-2264.jpg
Date: Sep 28
Second year / Male
Blue and black upperparts with patches of brown or green; brownish primary coverts contrasting with blue-edged greater coverts; moderately extensive white patches on primaries; relatively narrow and pointed rectrices.
Thumbnail - MG2-2600-16004-Setophaga_caerulescens_AOU_7_52-2254.jpg Thumbnail - MG2-2600-16004-Setophaga_caerulescens_AOU_7_52-2256.jpg Thumbnail - MG2-2600-16004-Setophaga_caerulescens_AOU_7_52-2255.jpg
Date: May 15

Additional age / sex class descriptions

The following additional age / sex class descriptions were found for this species:
Age / Sex   Age / Sex class description
After second year / Male Blue and black upperparts; blue edging to primary coverts; extensive white patches on primaries; relatively broad and rounded rectrices.
After second year / Female Greenish upperparts; pale greenish edging to primary and greater coverts; moderately extensive white patches on primaries; relatively broad and rounded rectrices with indistinct whitish patches on outer feathers.
Juvenile / Unknown Brownish overall, somewhat more buffy below; paler supercilium usually visible
Second year / Female Greenish upperparts; brownish primary coverts contrasting with green-edged greater coverts; white patches on primaries limited or absent; rectrices relatively narrow and pointed, with whitish patches small and indistinct or absent.
Number of species: 80

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