October - is
always a bit of a sad month as it's our last month of banding and
monitoring at Colony Farm for the season and banding normally calms
down as most neotropical migrants have headed south leaving us with
quieter fall days. That wasn't the case this month which saw huge
numbers of sparrows moving through the park and proved to be one of
our busiest months of the year with lots of species diversity!
Savannah, Song, Fox, White-crowned, Golden-crowned and
White-throated it really was 'sparrow month' and provided a great
opportunity to look at molt patterns in these species.
The two photographs
of White-crowned Sparrows (WCSP) below show how difficult ageing by
molt limits can sometimes be and how important it is to have
experience with the species banders are working with.
The 1st prebasic
molt is partial in WCSP and usually includes all lesser, median and
greater coverts, sometimes 1-3 tertials and sometimes up to several
The wing below left
shows a hatching year (HY) White-crowned Sparrow (WCSP) which had
completed its 1st PB and replaced all
lesser, median, greater coverts and carpal covert but nothing else -
no tertials or central retrices - the molt limit shown with the red
arrow between the replaced outer greater covert and retained inner
below right shows an after hatch year (AHY) WCSP in the final stages
of its definitive adult prebasic molt with P9 still in sheath and
final inner secondaries growing in (S6 indicated with a red arrow is
usually the last flight feather replaced in complete adult prebasic
molts in passerines).
sparrows also have the strong colour contrasts or pseudolimits
mentioned in previous blogs to further complicate matters. The blue
arrows in both photos below point to pseudolimits in both the HY and
AHY birds which can easily mislead banders in to thinking these
nicely edged inner greater coverts represent molt limits when in
fact they do not.
Tail shape is also
helpful in ageing many species being tapered and more abraded on
retained juvenal feathers in hatch year (HY) birds and broad and
truncate with a corner to the inner web and relatively fresh
feathers in after hatch year (AHY) birds. The outer retrices (R4-R6)
show the greatest age specific differences as can be seen in the two
photos below - the red arrow pointing to R5 on each bird.
The very fact that
tail feathers are frequently lost and replaced between normal molts
is one of the reasons why tail feather shape must be used with great
caution by banders, and only with other supporting characters (e.g.,
molt limits), when determining the ages of birds in hand.
Of course at this
time of the year the crown stripes of hatch year (HY)
White-crowned Sparrows are brown and after hatch year (AHY) birds
black and white making age determinations easy which is hugely
helpful to beginner banders studying molt limits in this species.
Continuing on the theme of
Zonotrichia Sparrows Golden-crowned Sparrows arrived in good
numbers this hatch year (HY) bird of unknown sex showing the typical
head plumage of a first year bird with light brown crown stripes as
opposed to the black crown stripes of its adult counterpart.
Again, the 1st PB is partial in this species usually including all
lesser, median and greater coverts but no tertials or retrices, the
molt limit shown with the red arrow between the replaced outer GC
and inner PC and again the pseudolimit shown with the blue arrow
pointing to the colour contrast between the richer brown inner
And two more
Zonotrichia sparrows turned up making almost a complete set of
North American Zonotrichs for October! This time two hatch year (HY)
White-throated Sparrows an uncommon bird for us and only the second
and third banding records for the station!
A few Orange-crowned Warblers (OCWA)
were banded at the beginning of the month this series of photos
showing a hatch year (HY) male OCWA (left) and an after hatch year
(AHY) male OCWA right.
In many species of warblers, sparrows and vireos the first prebasic
molt is partial with all lesser, median & greater coverts
replaced but no tertials or other flight feathers. In OCWA this
partial first PB can include a number of tertials and occasionally
The wing of the HY bird (below left)
shows a clear molt limit between the replaced outer greater
covert and retained inner primary covert - primary coverts are
retained feathers in all these examples of partial first prebasic
molts. The wing of the AHY bird (below right) is a prime example of
what definitive adult plumage, with no discernable molt limits among
the coverts or alula, looks like in fall. There was even
a trace of a feather sheath remaining on the outermost primary,
showing that this bird was near the very end of its complete
definitive prebasic molt. Also note the very broad, truncate inner
primaries and secondaries shown in this photo.
Tail shape mentioned in sparrows above
is also helpful in ageing wood warblers - HY retrices are again
retained juvenal feathers, are thinner, more tapered and less
durable and become worn more quickly as can clearly be seen in the
photo below left. The AHY tail (below right) are replaced adult
feathers, are broader, more truncate with an obvious corner to the
inner web and are simply better quality feathers with more structure
showing little or no wear.
Yellow-rumped Warblers in the fall is relatively easy with clear
molt limits showing between replaced greater coverts and retained
juvenal primary coverts and obvious alula covert (A1) and carpal
coverts (CC) molt limits shown with red arrows in the photo below
Sexing Yellow-rumped Warblers in the fall is all together more
difficult and often a complicated assessment of multiple plumage
characteristics and wing length.
Males tend to have broader and darker black side streaking than
females and the yellow spot under the wings also tends to be much
brighter and cleaner in males. In addition to side streaking, upper
tail coverts are useful in sexing some birds, males having feathers
with broad, dark black centers that are neatly and cleanly edged in
gray and female upper tail coverts have a narrower dark center band
and are broadly edged in gray with buffy/brown.
All of these characteristics were present with the bird below left
which was aged as hatch year (HY) based on the obvious molt limits
mentioned above and sexed as female. However, many Yellow-rumped
Warblers in the fall cannot be confidently sexed and are simply
recorded as 'sex unknown'.
(LISP) arrived in huge numbers the catch completely dominated by
hatch year (HY) birds showing clear molt limits between replaced
greater coverts and retained primary coverts (photo below left -
blue arrow) and strong alula covert molt limits (red arrow) between
the replaced alula covert (A1) and retained lower alula feathers (A2
Pyle indicates that
LISP only occasionally replace tertials
and sometimes central retrices but our experience with the
gracilis subspecies is that they almost always replace the two
inner tertials and central retrices as can be seen in the photos
below - the inner replaced tertials indicated with the green arrow
(photo left) and the central retrices (photo right) indicated with
the blue arrow the bird's right hand innermost rectrix (R1) still
growing in this example.
Although the first
prebasic molt in Redwing Blackbirds can be complete including all
flight feathers, the bright scarlet red epaulettes (lesser coverts)
and velvety black body plumage of this bird left as in doubt as to
its age as an after hatch year (AHY). Hatch year (HY) birds show
much duller epaulettes and body plumage.
This wing and tail
would have had us guessing if we hadn't seen the entire bird - It is
in fact a leucistic Common Yellowthroat!
Leucism is a condition characterized by reduced pigmentation caused
by a reduction in all types of skin pigment, not just melanin which
causes albinism. Melanin pigments strengthen feathers and make them
more resistant to abrasion.
Leucism is very rare in birds with only something like 0.0001% of
birds affected. These birds with abnormally white feathers are more
visible to predators so often do not survive long and those that do
may not be successful breeders having more difficulty attracting
This was the first
case of leucism we have ever seen in COYE.
And speaking of weird plumage aberrations the two birds left had us
momentarily doing double takes - The Bewick's Wren (photo left) was
the brightest individual we have ever seen with a bold white
supercilium, chestnut crown and auricular and a face pattern
reminding us more of a Carolina Wren than Bewick's!
We catch very few Bewick's Wrens but
the ones we have caught have not only been much grayer but also much
smaller than this individual. Subspecies references point to
Interior West (T.b.eremophilus) birds being larger and paler
with whitish underparts which matched this bird.
We would welcome any comments from other banders with experience
with this species and particularly with experience with the Interior
The very same day this bird showed up
amidst the hundreds of Purple Finches (PUFI) we have banded this
year. PUFIs are one of our most abundant species and this year will
vie for top 3 most banded birds so when it comes to PUFIs we think
we know when something looks different!
The things that struck us about this
bird was it's very bright supercilium and how crisply streaked the
underparts were. The other thing was the tiny bill being only 8mm
from nares to tip much too short to be a Cassin's Finch but below
the minimum length for PUFI too!
We came to the conclusion it was just
a bright hatch year (HY) PUFI with an unusually short bill but even
our most common birds can have us guessing sometimes!
The two male PUFI s below show more
'normal' bill sizes in this species and these photos show the
delayed plumage maturation transition male PUFIs make from brownish
birds in their first year to purple Purple Finches at their second
or first definitive adult prebasic molt in their second year.
They really were an
abundant species this year and invaded the park in huge numbers but
adult males like the bird below right were always a real treat and
reminded us of Roger Tory Peterson's famous description of the
'sparrow dipped in raspberry juice'!
Hummingbirds (RUHU) Anna's Hummingbirds (ANHU) are permanent
residents in the Vancouver area and therefore molt here on their
Both the first and adult prebasic molt is complete meaning all
feathers are replaced on both hatch year birds and adults.
Ageing Hummingbirds was discussed in
the June blog and is done by examining the bill under magnification
and looking at the extent of
corrugations along the lateral
portions of the upper mandible. The bills of adult birds like this
after hatch year (AHY) female are smooth, hard and shiny along the
entire length of the upper mandible.
ANHU are one of the eight species of
small gorgeted Hummingbirds in NA and have 10 primaries, the 10th
full in length, and unlike passerines only 6 secondaries and 10
retrices. This bird was in the midst of her complete prebasic molt
replacing all body and flight feathers.
are not common occurrences among the thousands of birds we band each
year but occasionally appear and take many different forms
from minor defects which do not appear to adversely affect the bird
to major defects which almost certainly affect the bird's chance of
Audubon's Warbler (photo right) had a trace of fat and weighed a
healthy 13.7 grams slightly above the average weight of 12.5 grams
for both males and females and was obviously not adversely affected
by the deformity.
The Spotted Towhee (photo below left) was a hatch year (HY) male
completing it's first prebasic molt and with an enormous growth on
the upper mandible. The bird was otherwise healthy weighing 38.7
grams grams but definitely not scoring on the cuteness scale!
The hatch year (HY) Black-headed
Grosbeak (photo below right) was missing half of its upper mandible
which one would think would almost certainly affect it's ability to
feed and chances of survival. Amazingly enough this bird weighed a
healthy 44 grams well within the average range for a hatch year bird
It's a tough enough life for a healthy
neotropical migrant let alone one with a major defect like this one
and it would be fascinating to see if this bird is able to survive
and return to us next year!
We've talked in
previous blogs about molt in non-passerines and how following their
first prebasic molt, hatching year (HY) woodpeckers 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.
This Downy Woodpecker 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 hatching).
With the turn of the calendar year
this bird will become an after third year (ATY) specifically a bird
alive in its fourth calendar year!
On the theme of woodpeckers this very
bright second year (SY) male Northern Flicker was banded - males of
course show the bright red moustachial stripe which is lacking in
females of this species.
And a new species
banded for the site occurred this month when not one but two
Wilson's Snipe (WISN) were captured. We regularly see and
occasionally flush WISN in the wet, grassy fields at Colony Farm and
were expecting one to show up in a net at some stage. We weren't
expecting it to be our net 6 though which is in the middle of a
thicket and probably the most unlikely of all of our nets to expect
one let alone two snipes!
camouflaged birds have long, flexible bills and the tips can be
opened and closed without movement at the base of the bill. Their
bills have sensory pits at the tip which allow the snipe to feel
prey when probing in deep mud.
October may be an
odd month to be talking about swallows but we received the draft of
the video from the
Western Wilderness Committee
which we helped to produce on the decline of Barn Swallows in Canada
back in July. Isabelle Groc (photo credit above) and Mike McKinlay
did an excellent job with the production of this project which will
be used to promote the fact that BC has no endangered species
legislation. Although BC has the greatest biodiversity in the
country, it is one of only two provinces in Canada – the other being
Alberta – that has no stand-alone law to protect endangered
The final version
of the video will be finished in December and we'll post a link for
anyone interested in viewing it.
Our final group
visit of the year occurred when we hosted students from British
Columbia Institute of Technology's (BCIT) Fish, Wildlife and
Recreation (FWR) program.
The FWR program prepares students for careers in the conservation
and management of fish, wildlife, parks and outdoor recreation and
we did a good job convincing them that their focus should be on on
avian and ecosystem conservation.
Everyone had a great time on a particularly busy morning with lots
of species diversity including the White-throated Sparrow and a
stunning Cooper's Hawk and we were definitely successful in swaying
some students to focus their studies on birds!
Kinglets came through the park in good
numbers during the month comprising a number of adult males
displaying prominent crown patches including the handsome after
hatch year (AHY) male Ruby-crowned Kinglet (below right) which had
the most extensive and vividly red crown patch we have ever seen.
Pine Siskins (PISI) are not common
birds for us preferring coniferous forests to the old field habitat
where we band.
Ageing PISIs is relatively easy with molt limits occurring within
the greater coverts on hatch year (HY) birds; the innermost glossy
black replaced GCs contrasting with the outermost retained juvenal
GCs as in the photo below left the molt limit indicated with the red
The after hatch year (AHY) wing (photo
below right) is uniformly adult with broad, truncate remiges
(primaries and secondaries) with an extensive yellow wing patch
which is lacking in hatch year birds.
The two tail photos below each wing
again show the characteristics of first year versus adult birds; the
hatch year tail left with tapered outer retrices with sharply
pointed tips versus the adult tail right with very broad truncate
outer retrices with a corner to the inner web and extensive yellow
which is also likely sex related being brighter and more extensively
yellow in males than females although care should be taken in
assigning sex categories to birds based purely on the extent of
yellow in the flight feathers as much overlap occurs.
This gorgeous hatch year (HY) Northern
Shrike (NSHR) of unknown sex was one of two NSHRs banded and proof
if we needed it that the fall banding season is almost over as
overwintering birds return to the park - the feint mask, brownish
plumage, heavy, dusky barring on the breast and underparts and very
obvious molt limit among the greater coverts of the wing allowing
for an easy age determination and this bird still showing the
remnants of a gape.
It was a good year
for us for Accipiters with 3 Cooper's Hawks and 7
Sharp-shinned Hawks banded, this tiny hatch year (HY) male showing
the characteristics of hatch birds with very dull, yellow eyes and
buffy fringing to the upperparts.
And this nice hatch
year (HY) male Varied Thrush added to species diversity for the
month another uncommon bird for us preferring mature coniferous
forests to the old field habitat where we band.
An enormous thank
you to all the people who have made 2011 such an amazing year for
VARC, to our sponsors and supporters MetroVancouver and Pacific
Parklands Foundation, our generous donors and friends of VARC, to
our patron Robert Bateman for his support but most of all to all of
our amazing volunteers who give freely of their time and without
whom we wouldn't have a banding program. These are the folk who set
alarms for unearthly hours during the summer months to get to the
banding station for pre-dawn on their weekends when everyone else is
having a lie-in and who do it all with such good humour....well most
of the time anyway!
It really is a privilege to have such a fantastic, fun group of
people who really have become like family to us.
Our winter banding
program will commence on December 1st when we scale back the
operation to a limited number of nets adjacent to our feeder station
at Colony Farm. Although not the most exciting time to be banding in
the Pacific Northwest it is an opportunity for volunteers to work on
their net extraction and ageing and sexing skills with our trainers
and for everyone to keep their hands in ahead of spring migration
banding again next year.
Finally, I wanted
to find a fitting end to our last blog of the year and the 2011
banding season at Colony Farm and couldn't think of a better one
than this extract from Miyoko Chu's great book "Songbird Journeys -
Four Seasons in the lives of Migratory Birds"
migratory birds cross our paths, they compel us to stop and marvel
at their beauty, their fluid lives in four seasons and distant
places, and the ecological intricacies they require to survive. As
the miracle of migration continues, the arrival of songbirds each
spring is a cause for celebration, for summer would not be the same
without them. In autumn, though, we cannot keep them; the songbirds
grow restless and depart, leaving us with emptier winter days and a
quiet reminder that we should not take them for granted."
Songbird Journeys – Miyoko Chu
See you all in
spring 2012 - Happy winter banding, ringing and birding!