Ageing and sexing details:
Males are easily recognized in spring by
their distinctive black facial mask, but close examination of the wing
and/or tail is usually required to determine age.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2005
On after-second-year Common Yellowthroats, the primary coverts have a
distinctive greenish outer edge, and all of them are fairly broad and
rounded. However, the appearance of some second-year birds is
quite similar, so this criterion is of relatively limited value.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2005
Largely because they spend more time in denser ground vegetation than
most other warblers, the rectrices of Common Yellowthroats can appear
rather worn and tattered by spring, regardless of age. However,
the wear tends to be less severe on after-second-year birds, and the
feathers are also typically broader and more rounded toward the tip,
though as the photo below shows, the wear on the feathers may make that
distinction difficult to assess reliably.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2005
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OVERVIEW
Females are easily recognized in spring by
the lack of any black on the face, but close examination of the wing
and/or tail is usually required to determine age.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2006
On after-second-year Common Yellowthroats, the primary coverts have a
distinctive greenish outer edge, and all of them are fairly broad and
rounded. However, the appearance of some second-year birds
is quite similar, so this criterion is of relatively limited value.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2006
Largely because they spend more time in denser ground vegetation than
most other warblers, the rectrices of Common Yellowthroats can appear
rather worn and tattered by spring, regardless of age. However,
the wear tends to be less severe on after-second-year birds, and the
feathers are also typically broader and more rounded toward the tip,
though the wear on the feathers may make that distinction difficult to
assess reliably.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2006
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OVERVIEW
Males are easily recognized in spring by
their distinctive black facial mask, but close examination of the wing
and/or tail is usually required to determine age. Sometimes on
second-year males the mask is slightly patchy, as in the photo below,
but confirming the age with other features is strongly recommended.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2006
On second-year Common Yellowthroats there is a moult limit between the
primary coverts and the greater coverts, but the contrast is often
slight and easily overlooked, as the photo below illustrates.
Where it is distinct, it can be taken as a reliable indicator of age,
but in most cases the tail will provide a clearer clue, and ideally both
should be assessed in tandem.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2006
The first photo below shows the condition of severe wear that many
second-year Common Yellowthroat tails are showing by spring, with
tattered edges and very pointed tips; the tail in the second photo shows
slightly less wear, but the rectrices are even more pointed. In
both cases, uniform growth bars can be seen across the tail, indicating
that the feathers grew simultaneously (as is the case when the first set
of rectrices grows in, but not with subsequent moults). While
useful if visible, they are not always present or visible, so their
absence should not be taken as an indicator of after-second-year.
Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2006
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OVERVIEW
Females are easily recognized in spring by
the lack of any black on the face, but close examination of the wing
and/or tail is usually required to determine age. Note, however, that on
this bird the throat is particularly pale and the greater alula appears
quite pale and frayed at the edge. Both of these features suggest
that it is a second-year female, but checking the wing and tail for
confirmation is strongly recommended.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2005
On second-year Common Yellowthroats there is a moult limit between the
primary coverts and the greater coverts, but the contrast is often
slight and easily overlooked, as the photo below illustrates.
Where it is distinct, it can be taken as a reliable indicator of age,
but in most cases the tail will provide a clearer clue, and ideally both
should be assessed in tandem.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2005
This photo illustrates the fact that some Common Yellowthroats replace
their central rectrices in their first prebasic moult - note how they
are fairly rounded and in good condition, compared with the five left
outer rectrices that are paler, more tattered, and at least in some
cases relatively pointed. After-second-year birds will have
replaced all rectrices during their moult, so a "mixed" tail such as
this is a good sign of a second-year bird.
Photo by Marcel Gahbauer,
McGill Bird Observatory, May 2005
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OVERVIEW
After-hatch-year
males are generally quite easy to recognize in fall as they are the only
age/sex class with an extensive black mask. However, there is some
potential for confusion between after-hatch-year males with particularly
mottled facial patches and hatch-year males with unusually extensive
black flecking, and especially in such cases the wing and tail should be
examined closely to confirm age. The two photos below are of the
same individual, one year apart; in 2006 it had nearly completed its
prebasic moult already, while in 2007 it was still well underway at the
time photos were taken.
Photo by Seabrooke Leckie,
McGill Bird Observatory, August 2006
Photo by Marie-Anne Hudson,
McGill Bird Observatory, August 2007
On after-hatch-year Common Yellowthroats, the primary coverts have a
distinctive greenish outer edge, and all of them are fairly broad and
rounded. However, the appearance of some second-year birds
is quite similar, so this criterion is of relatively limited value.
Especially in early fall, some birds may be seen with primaries and/or
secondaries being replaced, and this can be taken as confirmation of
after-hatch-year, as hatch-year birds do not replace any of these
feathers in their first prebasic moult.
Photo by Seabrooke Leckie,
McGill Bird Observatory, August 2006
Photo by Marie-Anne Hudson,
McGill Bird Observatory, August 2007
After-hatch-year Common
Yellowthroats have relatively broad and rounded outer rectrices, but
they may become fairly rapidly worn due to the dense habitat they
prefer. Note that in the example below some of the individual
rectrices have a fairly distinct tip, but that most feathers remain
fairly broad to near it, rather than tapering gradually toward the tip
as is more typical for hatch-year birds. Nonetheless, it can be
confusing enough that it re-emphasizes that this is a species for which
multiple characteristics should be combined to determine age. The
second photo shows the same individual one year later, and it appears to
have not yet moulted its tail.
Photo by Seabrooke Leckie,
McGill Bird Observatory, August 2006
Photo by Marie-Anne Hudson,
McGill Bird Observatory, August 2007
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OVERVIEW
Typical after-hatch-year females are
moderately recognizable in fall, as they lack any black on the face yet
have a distinctly yellow throat. Beware, however, some hatch-year
males that have not yet acquired any black in the face. Checking
the wing and tail to determine age will help resolve this uncertainty.
Photo by Marcel Gahbauer,
McGill Bird Observatory, September 2005
On after-second-year Common Yellowthroats, the primary coverts have a
distinctive greenish outer edge, and all of them are fairly broad and
rounded. However, the appearance of some second-year birds
is quite similar, so this criterion is of relatively limited value.
Photo by Marcel Gahbauer,
McGill Bird Observatory, September 2005
After-hatch-year Common
Yellowthroats have relatively broad and rounded outer rectrices, but
they may become fairly rapidly worn due to the dense habitat they
prefer. Note that in the example below some of the individual
rectrices have a fairly distinct tip, but that most feathers remain
fairly broad to near it, rather than tapering gradually toward the tip
as is more typical for hatch-year birds. Nonetheless, it can be
confusing enough that it re-emphasizes that this is a species for which
multiple characteristics should be combined to determine age.
Photo by Marcel Gahbauer,
McGill Bird Observatory, September 2005
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OVERVIEW
Typically
hatch-year males have some black flecking in the area of the facial
mask. However, in some it may be extensive enough to overlap with
relatively pale after-hatch-year males, and in other cases they may not
yet have any black at all and could be confused with after-hatch-year
females. In both cases, looking closely at the wing and tail for
other clues to determine age should resolve most questions.
Photo by Marcel Gahbauer,
McGill Bird Observatory, August 2005
On hatch-year Common Yellowthroats there is a moult limit between the
primary coverts and the greater coverts, but the contrast is often
slight and easily overlooked, though in the photo below it is actually
apparent. In cases such as this where it is distinct, it can be
taken as a reliable indicator of age, but in most cases the tail will
provide a clearer clue, and ideally both should be assessed in tandem.
Photo by Seabrooke Leckie,
McGill Bird Observatory, September 2006
Hatch-year Common
Yellowthroats have relatively narrow rectrices that are tapered to a
pointed tip.
Photo by Marcel Gahbauer,
McGill Bird Observatory, August 2005
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OVERVIEW
|
hatch-year
unknown (female?) |
Common Yellowthroats identified as
hatch-year through wing and tail characteristics, but lacking any black
on the face, are most likely to be females. However, as some
hatch-year males do not have any black on the face either, these should
generally be considered as sex unknown.
Photo by Marcel Gahbauer,
McGill Bird Observatory, August 2007
Photo by Marcel Gahbauer,
McGill Bird Observatory, September 2005
On second-year Common Yellowthroats there is a moult limit between the
primary coverts and the greater coverts, but the contrast is often
slight and easily overlooked, as the photo below illustrates.
Where it is distinct, it can be taken as a reliable indicator of age,
but in most cases the tail will provide a clearer clue, and ideally both
should be assessed in tandem.
Photo by Marcel Gahbauer,
McGill Bird Observatory, August 2007
Hatch-year Common
Yellowthroats have relatively narrow rectrices that are tapered to a
pointed tip.
Photo by Marcel Gahbauer,
McGill Bird Observatory, September 2005
RETURN TO AGE/SEX
OVERVIEW
