Ageing and sexing details:
|
JAN - JUL: after-second-year
unknown |
Body plumage provides relatively little
information about age and sex. Males average a more extensively
rusty crown, but there is considerable overlap and sex should be
determined only by brood patch or cloacal protuberance. In winter,
SY birds have less rufous in the crown than ASY birds, but by
March/April the prealternate molt has largely eliminated this
difference.
Photo by Marie-Anne Hudson,
McGill Bird Observatory (QC), April 2006
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), May 2006
ASY birds typically have distinct rusty edges to their primary coverts.
However, as shown by the photos on this page, the difference can be very
subtle, and it is recommended to also factor in the condition of the
tail, as well as crown, if applicable.
Photo by Marie-Anne Hudson,
McGill Bird Observatory (QC), April 2006
Photo by Peter Pyle, Merry Lea (IN), May 2007
A typical ASY tail is relatively broad, though by spring may be quite
abraded, especially at the tips. Beware, however, that Swamp
Sparrows occasionally replace their rectrices prematurely, and therefore
an adult tail is not in itself sufficient to conclude a bird is ASY.
The second photo below is of a known ASY bird, demonstrating how poor an
adult tail can look by spring.
Photo by Marie-Anne Hudson,
McGill Bird Observatory (QC), April 2006
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), May 2006
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OVERVIEW
|
JAN - JUL: second-year
unknown |
Body plumage provides relatively little
information about age and sex. Males average a more extensively
rusty crown, but there is considerable overlap and sex should be
determined only by brood patch or cloacal protuberance. In winter,
SY birds have less rufous in the crown than ASY birds, but by
March/April the prealternate molt has largely eliminated this
difference, although individuals with very little rufous (as in the
photo below) are more likely to be SY.
Photo by Marie-Anne Hudson,
McGill Bird Observatory (QC), April 2006
Photo by Barbara Frei, McGill Bird Observatory (QC), April 2008
SY
birds have minimal rusty edging on their primary coverts, and the outer coverts in particular tend to be relatively narrow and pointed.
Photo by Marie-Anne Hudson, McGill Bird Observatory (QC), April 2008
Photo by Barbara Frei,
McGill Bird Observatory (QC), April 2008
Swamp Sparrows of all ages usually have quite abraded tails by spring,
but those of SY birds tend to be particularly tattered, and much
narrower along the shaft of each feather, but there is a fair amont of variation as shown in the photos, and some overlap exists between lightly worn SY tails and heavily worn ASY tails.
Photo by Marie-Anne Hudson, McGill Bird Observatory (QC), April 2008
Photo by Marie-Anne Hudson,
McGill Bird Observatory (QC), April 2006
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OVERVIEW
|
JUN - DEC: after-hatch-year
unknown |
Body plumage provides relatively little
information about sex. Males average a more extensively rusty
crown, but there is considerable overlap and sex cannot be determined
reliably in fall, though in late summer it is worth checking for a brood
patch or cloacal protuberance. AHY birds typically have a
noticeable amount of rust on the crown, largely absent on HY birds.
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), August 2005
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), September 2008
AHY Swamp Sparrows usually have distinct rusty
edging along the primary coverts, which are broad and truncate.
The greater coverts also tend to be darker, and with a broader and
richer rusty border. If the primaries and/or secondaries are in active molt, as in the third photo below, that is a reliable indicator of an AHY individual.
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), August 2005
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), September 2008
Photo by Barbara Frei, McGill Bird Observatory (QC), August 2008
Rectrices of AHY Swamp
Sparrows are broader and more rounded than those of HY birds, but tails
can become quickly abraded at any age, and are best used as a complement
to other ageing criteria than as a primary indicator of age.
Photo by Marie-Anne
Hudson, McGill Bird Observatory (QC), September 2007
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), September 2008
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OVERVIEW
|
JUN - AUG: second-year
unknown |
In mid-late summer, it is occasionally
possible to age some Swamp Sparrows as SY. As all AHY birds will
be molting extensively at this time, the key is to look for retained
juvenile feathers, which are very pale and contrast sharply with
adjacent replaced feathers. In particular, note the extremely
faded and abraded juvenile alula in the photo below.
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), August 2005
The photo below illustrates a wing in mid-moult, with
one secondary just growing in, and all the inner ones still unreplaced.
Note the very old outer primary covert, as well as the unreplaced outer
two primaries.
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), August 2005
The tail is not helpful
in diagnosing individuals as SY. In this photo, all feathers are
already replaced; a bird caught in an earlier stage of molt would still
retain some old rectrices, but by this time of year they are likely to
be very worn regardless of age, and are of limited value for ageing.
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), August 2005
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OVERVIEW
|
JUN - DEC: hatch-year
unknown |
Swamp Sparrows with no or very little rust
on the crown are more likely to be HY birds, but this should always be
confirmed by looking at the wing and tail. Sex cannot be
determined for HY birds.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), September 2008
Photos by Marcel Gahbauer,
McGill Bird Observatory (QC), September 2005
Photo by Marie-Anne
Hudson, McGill Bird Observatory (QC), August 2008
HY Swamp Sparrows have dull wings, with relatively
narrow primary coverts that have minimal rusty edging.
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), September 2005
Photo by Marie-Anne
Hudson, McGill Bird Observatory (QC), September 2008
The photo below
illustrates a fresh HY tail, with the outer rectrices in particular
being narrow and pointed. These quickly become abraded.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), September 2008
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OVERVIEW
|
JUN - SEP: juvenile unknown |
Juvenile Swamp Sparrows largely lack the
rusty colouration that is otherwise typical of the species. They
can be recognized by the fine spotting on the upper breast, dark greater
coverts with rusty edges, and (if fully grown), shorter wing than Song
Sparrow and many other similar species.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), August 2008
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), July 2005
A fresh juvenile wing shows the dark greater coverts with rusty and buff
edging that are characteristic of Swamp Sparrows; ageing is more easily
accomplished by looking at the body overall. The second and third photos are of the same individual one week apart in late August; the second photo shows the greater coverts being replaced as part of the preformative molt.
Photo by Marie-Anne
Hudson, McGill Bird Observatory (QC), September 2007
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), August 2008
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), August 2008
Juvenile rectrices are narrow and tapered.
Photo by Marcel Gahbauer, McGill Bird Observatory (QC), August 2008
Photo by Marcel Gahbauer,
McGill Bird Observatory (QC), July 2005
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