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Number of species: 72

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Fox Sparrow - Passerella iliaca

Fox Sparrows can be relatively difficult to age, since age-related differences in wing and tail patterns are often subtle; especially by spring, a fair number of intermediates cannot be reliably aged.  Sex can generally be determined only by brood patch / cloacal protuberance during the breeding season, or by particularly short or long wing chords (e.g., for the eastern race <83 mm = female, >89 mm = male).

The four recognized subspecies differ somewhat in appearance and extent of molt, but the overall patterns are sufficiently consistent for ageing/sexing guidelines to apply to all of them

Quick Tips:

  • Look at the tail - outer rectrices are typically narrow and pointed on HY/SY, while broad and more rounded outer rectrices are typical of AHY/ASY
  • Check the outer primary coverts - they are relatively narrow and pointed with minimal pale brown edging on HY/SY birds, compared to relatively broad and rounded with distinct rufous edging on AHY/ASY birds

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 
After hatch year / Unknown
Wing largely uniform in colour and wear, with broad and rounded primary coverts and distinct rusty edging to greater coverts; broad and fairly rounded rectrices.
Thumbnail - MG2-1891-91070-Passerella_iliaca_AOU_7_52-1850.jpg Thumbnail - MG2-1891-91070-Passerella_iliaca_AOU_7_52-1852.jpg Thumbnail - MG2-1891-91070-Passerella_iliaca_AOU_7_52-1851.jpg
Date: Oct 28
Second year / Unknown
Relatively narrow primary coverts and limited rusty edging to greater coverts; somewhat narrow and tapered rectrices.
Thumbnail - MG2-1951-51376-Passerella_iliaca_AOU_7_52-1856.jpg Thumbnail - MG2-1951-51376-Passerella_iliaca_AOU_7_52-1858.jpg Thumbnail - MG2-1951-51376-Passerella_iliaca_AOU_7_52-1857.jpg
Date: Apr 22
After second year / Unknown
Wing largely uniform in colour and wear, with broad and rounded primary coverts and distinct rusty edging to greater coverts; broad and fairly rounded rectrices.
Thumbnail - MG2-2231-00898-Passerella_iliaca_AOU_7_52-1853.jpg Thumbnail - MG2-2231-00898-Passerella_iliaca_AOU_7_52-1855.jpg Thumbnail - MG2-2231-00898-Passerella_iliaca_AOU_7_52-1854.jpg
Date: Apr 14

Additional age / sex class descriptions

The following additional age / sex class descriptions were found for this species:
Age / Sex   Age / Sex class description
Hatch year / Unknown Relatively narrow primary coverts and limited rusty edging to greater coverts; somewhat narrow and tapered rectrices.
Number of species: 72

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