May is one
of our favourite months as the numbers of birds and diversity
increase as neotropical migrants move back through the park many of
them in bright alternate breeding plumages.
undertake this second prealternate molt in the late winter early
spring and none more noticeable than American Goldfinches (AMGO)
which are the only finches to change all of their body plumage twice
plumage, both age classes (second year - SY and after second year -
ASY) have very bright body plumage and soft part (e.g., bill)
coloration, but SY birds typically have dull greenish brown epaulets
(lesser coverts) at the bend of the wing as can be seen in the bird
ASY birds usually have bright yellow 'shoulders' although this
criterion alone is not altogether reliable for determining age of
AMGO males, because ASY males sometimes have dull greenish lesser
coverts, and SY birds sometimes will show precocious development of
bright yellow lesser coverts.
Ageing American Goldfinches is easier than in many species as there
are two ageing shortcuts banders can use. First we look for a buffy
tip on the carpal covert. At this time of the year only SY
birds have a buffy fringe to the terminal edge of this feather -
adults lack this buffy tip to the carpal covert (although they can
show a white tip) and in spring/summer AMGO’s are the ONLY birds
where we can use the prealternate molt for ageing as only SY birds
molt their inner GC’s as part of their prealternate molt.
The wing below
right shows these two ageing shortcuts - the blue arrow pointing to
the buffy tip on the carpal covert and the red arrow pointing to the
replaced inner greater coverts of this second year male's
prealternate molt this spring.
Warblers moved through in higher numbers than usual - this gorgeous
after second year (ASY) male showing the quintessential field mark
of the split eyering or eye arcs of this species and the wing
showing no discernible molt limits.
The first wave of
Orange-crowned Warblers (OCWA) contained almost all adult males like
the bird right showing extensive orange in the crowns and prime
examples of what definitive adult plumage, with no discernible molt
limits among the coverts or alula and truncate flight feathers
(primaries, secondaries and retrices), looks like in the spring.
Correctly sexing a
bird depends on correctly ageing it first always remembering that
young (HY/SY) males can look a lot like adult (AHY/ASY) females.
Such was the case
with this adult (ASY) female Wilson's Warbler showing a quite
extensive black cap which could easily be confused with a second
year (SY) male. The wing (below right) however again shows
definitive adult plumage, with no discernible molt limits among the
coverts or alula, nicely edged primary coverts and truncate brightly
edged green remiges (primaries and secondaries).
monitoring program kicked off this month as returning Rufous
Hummingbirds moved through the park. Our Hummingbird station
consists of 3 Hall traps (photo below left) each operated by an
electronic remote trap tripper (photo below right) which sits above
the trap and is triggered by radio control form the banding station.
Special thanks to
electronics genius and all round good guy Kyle Norris for building
our state of the art trap trippers which really are quite something!
Our very first
customer was the stunning adult male
Hummingbird mentioned in the April blog which had
overwintered in the park and which entered the trap quite literally
as we were setting it up and proving the old adage that there's no
such thing as a free lunch!
And this equally stunning adult male
Rufous Hummingbird which always have visitors captivated when they
hear of the amazing migratory journeys of these tiny birds breeding
as far north as Alaska and overwintering in Mexico - wings beating
at 60-80 beats per second, hearts beating at over 1,200 beats a
minute in flight and weighing little more than a Canadian penny!
Our May Bird
Monitoring and Banding Workshop was full with participants
sacrificing their weekend to learn about molt and ageing of NA
landbirds in the hand.
It always amazes us how people can progress from little or no
knowledge when they arrive on Friday lunchtime to extensive
knowledge by the end of the weekend. Before leaving the course we
ask them all to complete workshop evaluations and rate the overall
experience of the workshop from 1-10 and we were delighted to
receive a total score for our May workshop of 99% which was a record
and really pretty amazing!
Thanks to all our
course attendees for their kind comments which as always can be
viewed on our testimonials page by clicking
The workshop is a
pretty intensive 3 day course which focuses on accurate ageing and
sexing of NA landbirds using molt and plumage criteria. After
working late in to the evening on the Friday followed by two early
morning field sessions and more classroom work on Saturday and
Sunday by Sunday afternoon everyone is feeling the effects and we
called this photograph of one workshop participant "Molt Overload"!!
We had lots of visitors to the station again this month. A large
part of our mandate is public outreach and education to raise
awareness of environmental issues particularly as they relate to
habitat conservation for birds.
Much is being talked about regarding 'Nature Deficit Disorder' in
children these days, a term coined by Richard Louv in his 2005 book
Last Child in the Woods, referring to the alleged trend that
children are spending less time outdoors, resulting in a wide range
of behavioural problems.
We always notice how happy kids are when they are outside visiting
the banding station and interacting with wild birds and both these
young ladies were totally absorbed - Savannah on the left (really
should be holding a Sparrow!) helped ferry Hummingbirds back from
the traps to the banding table and Amy on the right concentrating on
the perfect shot of a nice male House Finch!
Speaking of kids
May saw the start of the VARC 'Birds are Brilliant' schools
program when we hosted a group of 70 Grade 7 students from Mulgrave
private school in West Vancouver.
The children were
split in to 3 groups and rotated between 3 stations - one where we
talked to them about the miracle of migration and the need to
safeguard habitat for breeding and migratory birds, one where they
had to collect information matching birds to habitats, song and food
sources and the banding station itself where they were able to
interact with wild birds.
At the end of the
morning we talked to them about birds and the environment and the
things they can do to help make a difference by being conscientious
consumers, keeping cats indoors and building bird friendly gardens
and campuses. Their homework project was to each build a simple
mobile to prevent window strikes.
We've always said
that if you put a wild bird in to a kids hand you have a convert for
life and although these kids may go on to all sorts of career paths,
they will never forget the unique experience of holding a migrant
warbler which like the two photos of Wilson's Warblers below may
have been in the tropical high plains of Costa Rica only a week or
The visit was an outstanding success
and seeing the look on kids faces as they held and released wild
birds was really priceless!
Is it a bird...is
it a plane...no it's Superwoman!
With all the visitors it's nice to
have some superhuman help! Here is Lois Lane (aka Sarah Gray) using
her kryptonian powers to band a Purple Finch during the Mulgrave
The first signs of
the breeding season were obvious this month with many resident birds
caught for banding already showing breeding characteristics.
This female Downy Woodpecker was showing a developed although not
fully vascularized brood patch (photo below left). Unlike in
passerines where the female does most if not all the incubation in
the near passerines such as woodpeckers males also incubate and
develop brood patches. In Downy Woodpeckers the female incubates
during the day and the male incubates at night.
Molt in near
passerines is also different than passerines allowing us to age
birds in to their fourth year. Its not until its third fall, when it
is a third year bird, that it replaces any inner primary coverts
and, as with this bird (photo below right), a few middle
juvenal primary coverts (now extremely brown and worn in comparison
to the recently molted primary coverts on either side) sometimes are
So, with the change of the calendar year the bird below becomes an
after third year, specifically a bird alive in its fourth calendar
Cowbirds (BHCO) were back in the park their liquid sounding gurgling
notes and thin, sliding whistles much in evidence this month.
Song learning in
BHCOs must be innate, since as brood
parasites the birds aren’t raised by members of their own species.
Males and females
have several different mates within a single season but we thought
this pair caught side by side made a very handsome couple at least
for the moment!
This spring has
been a record for us for Sharp-shinned Hawks banded with two more
this month - a second year (SY) male (left).......
.....and this adult female right!
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. At this time of the year second year PUFIs are
normally sexed as 'sex unknown' unless they have breeding
characteristics such as cloacal protruberances or brood patches.
This precocious second year male was the exception to the rule and
while not having the entire 'dipped in raspberry juice'
plumage of full adult males he was certainly unusually strongly
washed with purple leaving us in no doubt as to his sex. His first
prebasic molt after the breeding season last year included all
lesser, median and greater coverts and the carpal covert - molt
limits indicated with red arrows between the replaced outer greater
covert and retained inner primary covert and between the alula
covert and main lower alula feathers.
The photo below left shows why we call
PUFIs 'purple pinches' - unlike the similar House Finch, Purple
Finches always bite in the hand!
definitive prebasic molt after the breeding season this year our SY
male above will look like the 'sparrow dipped in raspberry juice'
The first of the
season's confusing Empids arrived with this 'Traill's'
Flycatcher. Showing all of the characteristics of an Alder
Flycatcher with a narrow, white eyering, greenish dorsal plumage,
pale lores and distinct crown spots this bird simply didn't have the
'feel' of a Willow Flycatcher and at the time WIFLs had not arrived
in the park.
Much is not know on
molting patterns in this species with more study needed. This after
second year (ASY) bird of unknown sex was showing clear molt limits
between replaced inner greater coverts and tertials presumably from
its prealternate molt which should have included primaries and
secondaries but didn't!
No such difficulties with this
gorgeous second year (SY) male Western Tanager showing clear molt
limits between retained juvenile feathers, first basic feathers (red
arrow) and first alternate feathers (blue arrows).
Equally easy to age
and sex was this adult (ASY) male Black-headed Grosbeak. Like Purple
Finches males do not get their adult plumage until their definitive
prebasic molt following the breeding season in their second year; SY
males vary from looking a lot like females to looking nearly like
We now have 18 nest
boxes for Tree Swallows (TRES) in the old field habitat creating
lots of nesting opportunities for these cavity nesters.
As both the adult
and first prebasic molt can be complete in TRES ageing this
species requires close scrutiny of the body plumage.
If there is any brown on the head or back the bird is a female and
varying amounts of brown indicate age as follows:
indicates a second year (SY) female
indicates an after hatch year (AHY) female
indicates an after second year (ASY) female
If the head and
back are entirely green-blue it may be a male of any age or an ASY
female at which point we measure the flattened wing chord as a
measurement below 114 mm bird indicates a female and one above 121
mm a male.
Our bird right was
aged AHY and sexed female based on wing chord.
first Swainson's Thrushes arrived 'home' this month with several
significant retraps including this bird banded in 2009 as an after
second year (ASY) then and now in at least its sixth calendar year!
Migration really is a miracle and it
never ceases to amaze us that these long distance migrants which
have possibly overwintered as far south as Argentina can navigate
back so precisely to the same location year after year returning not
just to the Lower Mainland or Vancouver but to the very same place
within Colony Farm often meaning we retrap birds from previous years
in the very same nets in which we caught them originally!
And finally this
second year (SY) female Yellow-headed Blackbird (YHBL) was a nice
surprise and new species banded for the station.
We have seen YHBL
only once before at our station feeders and again it was a female.
The marsh adjacent to the banding station has a large Red-winged
Blackbird (RWBL) colony and as YHBL often nest in the same marsh
habitat as RWBL it may be that this bird was scoping out a possible
nesting site there.
It was interesting to note an
unusually high number of YHBLs on a recent trip to the interior of
BC this year.
There are exceptions to almost every
rule in molt and ageing and YHBL is one of them. Unlike all of the
other Blackbirds which can have complete first prebasic molts YHBLs
In YHBL the 1st
prebasic molt is partial meaning only body feathers and some wing
coverts and possibly tertials and central retrices are replaced.
This 1st PB in YHBL
is supposed to include ALL median and greater coverts but no
tertials or retrices and little is know about the prealternate molt
which is suspected to be absent or limited.
This bird had
replaced only the 5 inner GCs and retained the outer 5 GCs, a clear
molt limit and 'step-in' indicated by the red arrow in the photo
In addition to the
yellow of the head and breast being mottled with brown in SY females
(photo above) the outer primary coverts are relatively tapered and
often have white tipping indicated by the red arrow on photo right.
Thanks to Mark
Habdas, Kerry Kenwood, Carol Matthews, Jason Jones, Jerry Rolls,
Debbie Wheeler, Sarah Gray (aka Superwoman!), Mike Nutter, Kyle
Norris, Eric Demers, Celia Chui, Louise Routledge, Monica Nugent,
Todd Heakes, Dev Manky, Marianne Dawson, Vinci Au, Sara Legros and
Hummer volunteers Marguerite Sans, Alida Faurie and Erin O'Connor
for their help with banding this month.