Migration Research Foundation - McGill Bird Observatory - Photo Library

McGILL BIRD OBSERVATORY

PHOTO LIBRARY

Swainson's Thrush (Catharus ustulatus)

Seasonal status at MBO:

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

common

fairly common

uncommon

rare

occasional

no records

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

Ageing and sexing overview:

January - July:

ASY - U Broad and rounded rectrices; outermost primary (p10) narrow and pointed.
SY - U Pale shaft streaks on outer greater coverts; rectrices narrow, tapered, and relatively worn; p10 broad and rounded

June - December:

AHY - U Broad and rounded rectrices; outermost primary (p10) narrow and pointed.
HY - U Pale shaft streaks on outer greater coverts; rectrices narrow, tapered, and relatively worn; p10 broad and rounded

Ageing and sexing details:

after-second-year unknown

Overall appearance is of no help in identifying after-second-year Swainson's Thrushes, and there are no plumage differences between sexes.

Photo by Marcel Gahbauer, May 2005

The greater coverts lack prominent pale tips or shaft streaks, but to confirm age as after-second-year, p10 should be confirmed as relatively short, narrow, and pointed, as in the second photo below.

Photo by Marcel Gahbauer, May 2005

Photo by Marcel Gahbauer, May 2006

The rectrices are broad and fairly rounded at the tip, generally in fair to good condition.

Photo by Marcel Gahbauer, May 2006

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second-year unknown

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after-hatch-year unknown

Overall appearance is of no help in identifying after-hatch-year Swainson's Thrushes, and there are no plumage differences between sexes.

Photo by Marcel Gahbauer, August 2005

There are no pale tips or shaft streaks on the greater coverts, and p10 (not visible in this photo) is relatively narrow, short, and pointed.

Photo by Marcel Gahbauer, August 2005

The rectrices are broad and fairly rounded at the tip, generally in fair to good condition.

Photo by Marcel Gahbauer, August 2005

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hatch-year unknown

In some cases, as in the second photo below, a Swainson's Thrush can be quickly identified in the field as a hatch-year by having prominent pale tips or shaft streaks on the greater coverts.

Photo by Seabrooke Leckie, September 2006

Photo by Marcel Gahbauer, August 2005

Not the distinct pale streaks along the shaft of the unreplaced greater coverts in the first photo; sometimes as in the second photo the pale tips are more evident. Although not visible in these photos, the broad, rounded, and relatively long p10 should also be used to confirm age as hatch-year.

Photo by Seabrooke Leckie, September 2006

Photo by Marcel Gahbauer, August 2005

Rectrices are relatively narrow, tend to be tapered to a point, and often show signs of wear.

Photo by Seabrooke Leckie, September 2006

Photo by Marcel Gahbauer, August 2005

RETURN TO AGE/SEX OVERVIEW