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Swainson's Thrush / Zorzal de Swainson (Catharus ustulatus) |
QUICK TIPS:
| 1) Look
at the greater coverts - the presence of buffy-white
shaft streaks indicates a HY/SY bird, however the
absence of buffy-white shaft streaks is NOT an
entirely reliable indicator of AHY/ASY, as some HY/SY
birds may lack these markings
2) Examine
the outermost primary (p10) - on HY/SY birds it
is rounded and 1 mm longer to 6 mm shorter than the
primary coverts, while on AHY/ASY birds it is
narrow, pointed, and 4-9 mm shorter than the primary
coverts
3) Look
at the shape of the rectrices - they are
tapered and relatively abraded on HY/SY birds, but
rounded and relatively fresh on AHY/ASY birds
Species account updated March 2009
Click here for additional photos of this species in the McGill Bird Observatory ID Photo Library |
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Ageing and sexing overview:
Ageing and sexing details:
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SPRING: ASY-U (after-second-year, sex unknown) |
Overall appearance is of no help in
identifying age of Swainson's Thrushes, and there are no
plumage differences between sexes.
Photo by Marcel Gahbauer,
Las Caletas (CR), April 2008
The greater coverts lack prominent pale tips or shaft streaks, but to
confirm age as ASY, p10 should be confirmed as relatively
short, narrow, and pointed, as in the second photo below.
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
The rectrices are broad and fairly rounded at the tip, generally in fair
to good condition.
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
RETURN TO AGE/SEX
OVERVIEW
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SPRING: SY-U (second-year, sex unknown) |
Overall appearance is of no help in
identifying second-year Swainson's Thrushes, and there are no
plumage differences between sexes.
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
There are often pale tips or shaft streaks on some
greater coverts, and p10 (visible in the second photo) is relatively
long and rounded.
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
The rectrices are relatively narrow and pointed, and generally in fair to poor condition.
Photo by Marcel Gahbauer, Las Caletas (CR),
April 2008
RETURN TO AGE/SEX
OVERVIEW
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