Fall (September - October 2013)
September is always
an exciting month at Colony Farm as dispersing hatch year birds
flood the park bringing with them the potential of a vagrant bird
well outside of its normal geographical range.
Such was the case
this September when we met one morning at 6.30 am which seemed
ridiculously late given we were getting up at 3.30 am to get to the
banding station pre-dawn in June! By now the main push of migrants
was over and after a clear night we weren't expecting a busy morning
but this one turned out to be all about quality rather than
On the way in to
the station we were talking about confusing fall warblers as we had
just finished doing a book review for The Warbler Guide by Tom
Stephenson and Scott Whittle and it sometimes seems like karma when
something like this happens.
It was chilly first
thing with frosty nets and the early net rounds were not very
productive with Neotropical migrants
few and far
between, the first Ruby-crowned Kinglets and Golden-crowned Sparrows
definitely heralding that fall was just around the corner. But in
banding as in life you never know what's around the corner and the 8
am net round produced the bird of the year for us!
With the bird in
hand and only looking at the face you could easily be forgiven for
calling it a first fall female Yellow-rumped (Myrtle) Warbler with
the pale throat wrapping around behind the auriculars and dull
plumage with faint, diffuse streaking and brown back. But on closer
inspection the face pattern is different with the prominent
supercilium although quite narrow and buffy in this individual. And
then there are some of the 'eastern' warblers like Blackpoll,
Bay-breasted or Cape May (or even a mega-rarity like Pine!) which
can all look quite similar, especially first fall birds in dull,
But as can be seen
from this side view the undertail coverts are yellow, the tail long
and the black tail base and white pattern diagnostic for Palm
Warbler, a new species for the station and our 92nd banded during
our banding and monitoring studies.
The 1st prebasic
molt in Palm Warbler is partial and includes all lesser, median and
greater coverts but no flight feathers (primaries, secondaries or
rectrices) - the molt limit indicated between the outer greater
covert and inner primary covert with the red arrow in the photo
below. Notice also the very narrow and tapered retained juvenal
The amount and
extent of white on the outer rectrices (R5 & R6 in the photo above
right) is also age (and sex) related in Setophaga warblers
and is less extensive in HY/SY birds not extending to the inner
Vagrant birds are exciting for birders and banders alike but they
also have scientific value. Long term data sets may provide evidence
for historic changes in population sizes and understanding the
patterns of such occurrences is important in increasing our
knowledge of dispersal of species. These long range dispersal events
may also be critical for the survival of many species in the face of
the anthropogenic climate changes we are seeing.
Another example of this could be the
regular occurrences of Northern Waterthrush (NOWA) each fall in the
park. This rare transient in the Vancouver area is becoming an
expected capture for us at this time of the year. All of the NOWAs
we have caught including this one have been hatch year birds based
narrow rusty tips to the tertials and narrow,
more tapered rectrices.
Long term monitoring helps establish
abundance patterns for more common species as well. This fresh
plumaged hatch year (HY) Dusky Flycatcher (DUFL) was another
surprise during September. Although DUFL appear in small numbers in
the spring, fall records are less common for us.
We've talked before about confusing
Empidonax flycatchers in previous blogs and how we use wing
morphology on birds in the hand to identify them to species. The
primary tip spacing on this particular DUFL was somewhat unusual in
that normally it is quite evenly spaced but on this bird there was
quite a gap between primaries 5 and 6 (photo below right).
The head shape was
also less rounded than on other DUFL we have banded although
everything else fitted - the gray head contrasting with the greenish
back, the overall slim shape and narrow tail base, the contrasting
white outer edge of the outer rectrix (photo above), the
contrastingly pale lores and almond shaped eyering and very short
primary projection (photo below). Finally, the outer primary (P10)
is shorter than primary 4 (P4) in this species (insert photo below)
allowing us to make a definitive identification of this particular
The last of the
locally hatched birds appeared in September including this recently
fledged Ring-necked Pheasant. Ring-necked Pheasants are common in
the park and we often flush them on early morning net rounds when
they explode under your feet and fly away making their loud, harsh
alarm calls. Adults are too heavy to be caught in our passerine nets
but occasionally baby birds like this one are caught in the bottom
shelves and although as introduced game birds we are not able to
band them they do make for great photo opportunities!
2013 has been an
extraordinary year for Anna's Hummingbirds which have firmly
established themselves in the Vancouver area in recent years. This
hatch year male was molting in the iridescent magenta-pink feathers
of the head and throat diagnostic of adult males.
We maintain hummingbird feeders
throughout the winter but still marvel how these tiny birds are
capable of toughing out Vancouver winters when we often find the
nectar frozen when we arrive at the station in the mornings.
September also sees the final stages of molt for many species which
complete their prebasic molt on their breeding grounds.
Birds in active molt are very helpful
to banders learning ageing strategies using molt and plumage
criteria. These 'molt limits in the making' allow us to see the
sequence of events unfold as birds go through the molting process
and to memorize the differences between retained and replaced
feathers to help us when looking at these same species later in the
fall and winter.
The wing of this after hatch year
(AHY) male Common Yellowthroat (photo below left) shows the very end
of this bird's definitive adult prebasic molt when all body and
flight feathers are replaced. Primaries molt distally (away from the
birds body) with the outermost (P9 or P10) normally the last
replaced. Secondaries molt proximally (towards the birds body) with
the innermost (S6) normally the last flight feather replaced. In
this photo P9 is still in sheath and S6 not quite fully grown (both
indicated with reds arrows).
Banders must be careful however with
species like Common Yellowthroat which can often have very extensive
1st prebasic molts including some outer primaries and inner
secondaries, and look closely at the rachis colour which is
typically darker/blacker on molted feathers and lighter/browner on
retained juvenal feathers. In this wing all of the remiges have been
replaced and the rachises are all black and of the same diameter in
each feather group.
The rectrices of the same bird (photo
below right) show the rounded, more truncate shape typical of adult
birds although we have noticed that when these feathers are very
fresh they can tiny sharp tips on the very ends.
This hatch year
(HY) Song Sparrow (SOSP) was in the final stages of its 1st prebasic
molt having replaced lesser, median and greater coverts and with all
3 alula feathers and all 3 tertials still in sheath (indicated with
Notice the very
washed out and brown appearance of the primary coverts (blue arrow)
which lack the sheen and have browner rachises than the molted
When is a
Purple Finch not a 'purple' finch? Well,
normally if it's a female or young male as male PUFIs don't get
their purple plumage until their definitive adult prebasic molt in
their second year. This answers many peoples' question "Why are all
the Purple Finches at my feeder females?" The answer is they're
probably not but either females or young males.
The two wings below
show examples of adult male and female PUFIs in flight feather molt.
The wing below left shows an after hatch year (AHY) female in the
early stages of replacing all of its wing feathers. The definitive
adult prebasic molt in passerines starts with the lesser and median
coverts, then tertials and innermost primaries, primary replacement
proceeds distally towards the outermost primary, primary coverts
molt with the corresponding primary as can be seen here and greater
coverts molt shortly after the start of the primaries which is the
stage at which this photo was taken.
Although aged as an
after hatch year (AHY) this bird was almost certainly a second year
bird (e.g. born in 2012) based on the very worn, tapered as yet to
be replaced primaries, secondaries and alula. Compare the shape of
the very broad, truncate replaced inner primaries and the very thin,
tapered and worn adjacent outer primaries.
The wing below right shows a male in flight feather molt - this time
there is no doubt as to the age of this bird - a second year male
replacing brownish contour and flight feathers with purple washed
feathers diagnostic of adult males.
Family Day was a huge success with parents and kids alike having a
great time. It was a busy day with lots of birds and species
diversity and a fantastic opportunity to talk to kids about birds
and the environment and what they can do to help make a difference.
It was as much fun for all of us at
the station and we plan to host a Family Day each month from May to
October next season!
The photo below is of three
Banders-in-the-making helping ferry birds back to the station for
of a success was our Northern Saw-whet Owl (NSWO) monitoring which
was in fact a complete disaster!
We spent four nights during the period out in the park from dusk
until midnight with the audio lure going full blast at our 'playback
nets' which occupy an area of the park which represents perfect
habitat for Saw-whets.
Unfortunately, we did not hear, see or
catch a single NSWO but did have a visit from this spectacular
Barred Owl which sat a few inches above our nets one night allowing
us to get within a few feet and spotlight it for photographs. Barred
Owls are very aggressive predators of smaller owls so we were not
sorry that it moved off and didn't appear again.
however catch this gorgeous Long-eared Owl (LEOW) during our normal
diurnal banding activities!
and sexing LEOWs like other raptors can be tricky and this bird was
Hatch year (HY) LEOWs retain all juvenal flight feathers resulting
in primaries and secondaries appearing tapered and uniform in wear.
The numbers of dark bars on the flight feathers are relatively large
and the distance between them relatively small versus adults where
the primaries and secondaries are fresh and more truncate and the
number of bars relatively small and the distance between them
relatively large. But this is all quite subjective and wasn't helped
by very poor light and early morning fog which didn't make for good
photographs of flight feathers which we could examine later. Our
thoughts were that this individual was likely a hatch year year bird
based on the flight feather criteria mentioned above but adding to
the confusion was the very yellow iris which is more indicative of
an adult which left us ageing this LEOW as simply unknown.
Either way there is
something very special about all owls and they are among everyone's
favourites as can be seen from the photos below of the two Sarahs!
(All owl photos courtesy of Debbie Wheeler)
non-passerines is certainly less tricky and with woodpeckers we can
age beyond the maximum after second year designation of most
We've talked in previous blogs about molt in non-passerines and how
following their first prebasic molt, hatching year (HY) woodpeckers
like the male Downy Woodpecker below retain all of their juvenal
primary coverts. Second year (SY) birds have all juvenal primary
coverts until their second prebasic molt, when they replace up to
several outer juvenal primary coverts.
Flicker below was a 3rd year bird based on the presence of three
different generations (one being juvenal) among the feathers of the
wing. The wing below shows the typical mixture of retained (more
brown and worn) juvenal middle primary coverts and fresher (blacker
and less worn) second basic outer primary coverts (i.e., molted in
the birds' second fall after hatching) and third basic inner primary
coverts (i.e. molted this year in the bird's third fall after
With the turn of the calendar year
this bird will become an after third year (ATY) in 2014,
specifically a bird alive in its fourth calendar year!
The first signs of
fall were the arrival of winter visitors which included two uncommon
species for us, two American Tree Sparrows and this White-throated
Sparrow showing the distinct streaking to the central breast
indicative of hatch year birds.
Molt limits in
Zonotrichia sparrows can be tricky given the strong colour
contrasts in the greater coverts. These so called pseudolimits (blue
arrow - photo below left) simulate a molt limit but close
examination of feather wear to the tips shows that these feathers
are in fact the same generation and the molt limit is between the
outer greater covert and inner primary covert and alula covert and
lower alula feather as indicated by the red arrows.
The 1st prebasic
molt does not include any flight feathers, the retained outer
juvenal rectrices relatively narrow and tapered (photo below right).
And shrieks of pain
at the nets announced the arrival of the first Northern Shrikes
which although such stunning birds are probably our most aggressive
species in the hand with that lethally hooked bill easily drawing
blood and everyone at the station quickly bore the scars of
extracting and processing these predatory songbirds.
breed much further north in the taiga and tundra and some overwinter
in the park. Hatch year (HY) birds like this one are more brownish
overall than adults with prominent molt limits in the wing and have
distinct barring on the chest and less distinct face masks. In
adults the strongly hooked bill becomes darker and develops a
sharp ridge to grip prey and is an even more
fearsome weapon to be avoided by banders!
So, that's it for
another season at Colony Farm in which we again achieved a number of
As always none of
it would be possible without the help of so many people which now
seemingly includes a cast of thousands between all of the Friends of
VARC, our sponsors and donors, visitors, workshop participants and
of course all of the VARC volunteers who sacrifice their weekends
and set alarms for unearthly hours during the summer months mostly
on their weekends off to help with banding operations - again thank
See you all in spring 2014 - Happy winter banding, ringing and
birding wherever you are in the world!
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