- April started off cold and wet in Vancouver and it looked as
though winter was never going to end. After 6 months of cold, short,
dark days we were all questioning our sanity living in the Pacific
We were rained
out on all but a few days with torrential rain and at one point the
banding station was under water and we were plotting how to catch
the mallards floating around our bird feeders!
indication of spring was the arrival of Red-winged Blackbirds
(RWBL), the males perched above our feeders blasting out their
conk-la-ree song all day!
Ageing male RWBLs
is easy at this time of the year as
(SY) males do not have the brilliant red epaulettes
(lesser coverts) of
Ageing females is all together more difficult. Although the first
prebasic molt can be complete in RWBLs, underwing coverts are often
retained juvenile feathers. In males these retained feathers
contrast markedly with adjacent replaced blacker feathers but in
females these molt limits are much more difficult to see. This
particular second year (SY) female did however show a strong molt
limit (indicated by the red arrow pointing to replaced feathers and
blue arrow pointing to retained feathers in the photo right).
weather finally broke and spring arrived and as always we forgave
Vancouver the 6 months of winter as the azaleas and rhododendrons
bloomed and Vancouver looked its stunning best!
(TRES) arrived in March braving the cold and torrential rain. Unlike
other aerial insectivores TRES have the ability to use plant foods
to survive periods of food shortages which can be the only reason
our birds survive so early in the season.
By April they are already checking
out boxes - we now have 30 boxes for them as part of our TRES
monitoring program although the boxes are occasionally hijacked by
Black-capped Chickadees which are early nesters and by the end of
the month were already incubating eggs.
Tree Swallows build nests made of
grasses lined with feathers. The TRES at Colony Farm have a
preference for the contour feathers from Ring-necked Pheasants which
are abundant in the park and used exclusively by our birds.
Black-capped Chickadee nests are made
entirely of mosses (photo below left) lined with fine hairs, fur and
other soft material.
Breeding birds develop breeding
characteristics which help us to separate males from females in
sexually monomorphic species like Black-capped Chickadees.
Many species are sexually dimorphic meaning we can sex the bird
based on characteristics such as plumage coloration and/or size. But
in sexually monomorphic species both males and females look exactly
alike and these species can only be sexed in the hand in spring and
summer when they show these breeding characteristics i.e. a cloacal
protuberance (CP) or a brood patch (BP).
In many monomorphic species, the
male's cloaca becomes enlarged and bulbous during the breeding
season, the base narrow and tip swollen, the purpose being to store
sperm and aid with copulation. This is called a
cloacal protuberance, or
Female passerines on the
other hand conduct most if not all of the incubation and develop
brood patches (BP). At this time they will lose the feathers on the
breast and belly to facilitate direct skin contact and maximum heat
transfer to the eggs for incubation.
The photo below right shows a fully
developed brood patch with wrinkled and highly vascularized skin.
The development of the brood patch progresses in stages similar to
the development of the cloacal protuberance of the male, the
feathers of the breast and belly are first shed and the blood
vessels under the skin increase in size and number until the brood
patch is edematous (i.e. highly vascularized and swollen) such as in
the photo below right of a female Black-capped Chickadee with a
fully developed brood patch.
the change of weather the first wave of migrants arrived including a
number of Yellow-rumped Warblers, this dazzling male Myrtle Warbler
in full alternate (breeding) plumage. The early returning migrants
are such a welcome splash of colour after months of drab resident
birds in basic, winter (non-breeding) plumages and we all get
excited wondering what each net round will produce!
Ageing and sexing
wood warblers in the spring requires a complete understanding of the
molt cycle of the individual species being studied. All of these
birds will have undertaken a prebasic molt following the breeding
season last year when adults replace all body and flight feathers.
In species where the annual prebasic molt is the only molt occurring
annually breeding occurs in basic plumage and the result when
looking at an adult bird, which has undertaken this complete
definitive prebasic molt, in the spring is that there are no
discernible molt limits on the wing between replaced and retained
However, in many
species there is a SECOND molt that occurs in the late winter /
early spring prior to the next prebasic molt. This molt called the
prealternate molt occurs in both adults and first year birds so that
in the spring first year birds will show three generations of
feathers but adults will also show molt limits. In adults however
there are only two generations of feathers, adult prebasic and adult
The after second
year (ASY) male Myrtle Warbler wing below is showing such a molt
limit (shown with red arrow) between the outer four greater coverts
replaced as part of the birds definitive adult prebasic molt last
year and the six inner greater coverts replaced as part of its adult
prealternate molt this spring.
Hummingbird monitoring began the first week of May with both Anna's
(ANHU) and Rufous (RUHU) Hummingbirds caught for banding.
ANHU are now common birds along the
Pacific coast and throughout the Vancouver area, their range having
increased dramatically since the 1930s, when they were found only in
California and Baja California. The combination of the
planting of exotic flowering trees in parks and gardens and the
widespread use of backyard nectar feeders have resulted in its
breeding range expanding as far north as the Comox Valley on the
east coast of Vancouver Island.
Adult males like this one really
are like flying jewelry with their iridescent magenta-rose
crown and throat feathers. And for a truly spectacular photo of an
adult male Anna's Hummingbird click on our
of the Month!
RUHU arrived early and in good
numbers adding to the activity around our traps and feeders with
both males and females caught for banding.
We love RUHU which always look
grumpy in the hand and all marvel at these tiny birds weighing
little more than a Canadian penny, whose wings beat up to 80 times a
second and hearts beat over 1,200 beats a minute in flight and to
think these tiny dynamos breed as far north as Alaska and overwinter
Please see our
2012 June blog
for a whole photo essay on ageing and sexing RUHU.
The gorgets of hummingbirds contain
highly iridescent feathers which are among the most specialized
feathers in all bird species. It’s not pigments that give the
feathers colour but the refracted light falling at certain angles on
Only a portion of each feather is modified for iridescence but the
overlapping of adjacent feathers creates the unbroken colour effect
of a single block of feathers as can be seen in the photo below of
an adult male RUHU.
Apodiformes which comes from the Greek word meaning 'no feet'
and although they do of course have feet to perch they are too far
back on their bodies to walk. This means that a Hummingbird placed
on a hand will normally stay there for a few moments allowing for
fabulous photo opportunities for visitors who never fail to be
totally captivated by them like this after hatch year (AHY) female
One RUHU male had us scratching our
heads wondering if it could possibly be a male Allen's Hummingbird
ALHU only breed along a narrow strip
of coastal California and southern Oregon and are very difficult to
separate from RUHU. This particular bird had extensive bronze-green
upperparts unlike anything we'd seen in adult male RUHUs before.
Unlike passerines hummingbirds have
only 10 rectrices (numbered centrifugally from inside out) and in
RUHU r2 has a more distinct notch than in ALHU as
can be seen in the photo right.
Our conclusion was
that this was likely a second year (SY) male RUHU which had retained
extensive juvenile plumage.
A full house for our April Bird
Identification Workshop when another great group of people
sacrificed their entire weekend to learn about the birds and
habitats of the Vancouver area.
The ID Workshop is always a lot of
fun and an opportunity for us to get people hooked by showing them
many of our breeding and migratory birds up close and personal
during our field session to the banding station.
Our Bird ID Workshop is gaining
notoriety and once again we were really overwhelmed with the
feedback we received from workshop participants and thank them all
for their very kind and generous course evaluations which can be
|The next weekend
13 students from the British Columbia Institute of Technology (BCIT)
Fish, Wildlife and Recreation program.
Tom Saare the BCIT FWR Program
Instructor was kind enough to send us a note to say:
"Thanks for the great bird banding sessions on Saturday and Sunday.
I know that all of the students thoroughly enjoyed the experience
and it was a tremendous learning opportunity as well."
A large part of VARC's mandate is
public outreach and education to raise awareness of environmental
issues particularly as they relate to birds and our visitor schedule
is booked solid for spring with visitors almost every weekend!
in turn was followed by the May Bird Monitoring and Banding Workshop
- no rest for the wicked!
Once again a really great group of people spent a long and tiring
weekend both in the classroom and out in the field learning all
about ageing of NA landbirds in the hand. We had our first ever
maximum workshop evaluation score with everyone scoring us a 10 (in
fact two people scored us 11 and 15 out of ten respectively!)
Thanks to everyone who made the
weekend such a success and to the workshop participants for their
very kind and generous comments which as always can be viewed on our
workshop testimonials page.
||A huge irruption
of Pine Siskins (PISI) over the winter resulted in large numbers of
this species at feeders throughout the lower mainland and at the
banding station which is very unusual for us in the old field
habitat where we band.
These gregarious little birds spend
their lives in loose flocks ranging widely and erratically across
the continent each winter in response to seed crops.
We did a photo essay on ageing and
sexing PISI in our
October Blog. The wing
of this after second year (ASY) bird showing no discernible molt
limits and extensive yellow wing and tail patches which is 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.
also talked previously about 'brown' Purple Finches (in our
last year) and how delayed plumage maturation in this species
results in young males looking a lot like females.
This beautiful adult after second year
(ASY) male leaving us in no doubt as to its age and sex or as to why
Roger Tory Peterson described this bird as the 'sparrow dipped in
Savannah Sparrows (SAVS) returned to the park their loud, buzzy,
insect like song resonating around the old field habitat where we
This previously banded bird
returned and was recaptured in the very same net as in previous
years indicating the high site fidelity of this species and the
importance of safeguarding precise habitats for returning breeding
The 1st prebasic molt is partial in
SAVS and usually includes all median and greater coverts and 1-3
The prealternate molt includes no
greater coverts, usually 1-3 tertials and occasionally central
This adult after second year (ASY)
bird (photo right) had indeed replaced the single innermost tertial
as part of its adult prealternate molt this spring but had also
unusually replaced a number of median coverts too! (indicated with
The tertials on these birds are
much longer than most other passerines, extending almost as long as
the outer primaries, a characteristic unique to grassland sparrows
and other ground dwelling finch species. The elongated claw on the
hind toe, or hallux, which is unlike those seen on most "perching"
birds is another characteristic of Savannah Sparrows and other
grassland birds, like longspurs and pipits, that probably aids in
stability and movement across the flat, open areas where they feed
Unlike many of the Savannah Sparrows
which return to the park to breed many migrants are just passing
through stopping in the old field habitat to rest and refuel ahead
of long migratory journeys.
Orange-crowned warblers (OCWA) came through in good numbers. We
commonly see three of the four subspecies at Colony Farm and plumage
colour differs quite dramatically between them. The
Pacific Coast form,
is bright yellow, the celata
subspecies is found in Alaska and across Canada, and is the dullest
and grayest and the orestera subspecies intermediate in
appearance (photo below left).
Where birds store fat and how we score fat deposits was explained in
a photo essay in the 2011 September blog
2011 Blog). This
particular OCWA had a maximum furcular (the area between the
fused clavicles) fat score. The caloric density of this amount of
fat is easily sufficient to sustain the energy demands of a small
migrant warbler like this one making a non-stop nocturnal flight of
possibly 700 kms or more. And this is one of several such flights
this bird will need to make to take it from it's southern winter
grounds to its Canadian nesting grounds.
Bird banding data provides a very
important category of evidence for assessing and confirming the
value of areas and habitats for migratory birds. By recording a
measure of visible fat on migrants caught for banding and
documenting changes in body mass and fat deposits through subsequent
recaptures allows us to directly assess the quality of sites and/or
habitats birds are using.
When ageing passerines banders look
for at least two indicators of age before making a decision - the
presence or absence of a molt limit (the boundary between a retained
juvenile feather and a replaced feather) and at least one other. One
indicator could be the shape and quality of the primary coverts
which are retained juvenile feathers in many examples of
partial/incomplete 1st prebasic molts. The wing below shows a second
year (SY) Lincoln's Sparrow with worn and very tapered primary
coverts with little or no edging versus the primary coverts of an
adult bird (overlaid photo) showing broad, truncate primary coverts
with very little wear and prominent edging to the feathers.
We'll leave it to you to decide where
the molt limit is on the SY bird! (answer at the end of the blog!)
I use the word stunning far too often
to describe birds but how else could you describe this adult male
Lazuli Bunting? Beautiful, marvelous, brilliant, dazzling, gorgeous,
handsome, heavenly, impressive, lovely, out of this world, pretty,
ravishing, sensational, smashing, spectacular, striking, wonderful -
Members of the Cardinalis
family (Grosbeaks & Buntings) often have an extensive molt including
all greater coverts, carpal covert, alula, tertials, additional
inner secondaries and outer primaries as can be seen in the photo
below right. These species, where males have such contrasting and
distinctive plumages are helpful for learning molt patterns and this
can be particularly helpful in looking for molt limits in females of
the same species.
Our after second year (ASY) above had
no discernible molt limits on the wing (below) with brightly edges
primary coverts, alula and remiges. A second year male would show
very obvious molt limits as in this photo of a bird banded at Colony
Farm in July 2011:
second year (SY) male
Sharp-shinned Hawks are frequent captures for us this second year
(SY) male showing the dull eye and buffy fringes to the wing coverts
diagnostic of first year birds.
Mourning Doves are
common doves across most of North America but uncommon for us in the
old field habitat where we band at Colony Farm but our newly
designed and built
J-Trap has proved very
successful at catching these elusive birds.
Adult Males have a
powder blue crown and nape, a well-developed blue-black spot on the
neck, a rosy breast, and a dazzling patch of iridescence on the side
just at the bend of the wing.
Adult females like this one have a brownish cap, the blue-black spot
is small, iridescence is generally lacking, and the overall
appearance is more drab. Females are also smaller, by 5-10%.
speaking of the J-Trap this gorgeous, previously banded adult male
Black-headed Grosbeak arrived back and was captured in the trap. It
was the first of the season BHGR and nice to have him back despite
the fact that he was particularly aggressive biting everything and
everyone in sight!
The photos below are prime example of
what definitive adult plumage, with no discernible molt limits among
the coverts or alula, looks like in spring. The wing also shows an
extensive white wing patch and the flight feathers (primaries,
secondaries and rectrices) are all broad and truncate.
STOP PRESS AND STOP THE
PIGEON!! (For any of you
under 40 who never saw the Dick Dastardly and Muttley cartoons
you’ll need to click here first:
Stop the Pigeon
I was supposed to
be banding this particular Friday morning but had to go in to the
office for an early conference call and my nemesis bird turned
up…..and not one of them but THREE!! This photo is called three smug
P.S. I have to add
they only caught them because of my dastardly plan to build a J-Trap
especially for this special species study bird!
And stop the press one last time for
the first net round on May 19th which produced only our second ever
Long-Eared Owl scoring maximum oohs and aahs from everyone at the
The molt limit on the Lincoln's Sparrow above is between the outer
replaced great covert and inner retained primary covert and between
the replaced alula covert and retained lower alula feather from the
birds 1st prebasic molt following the breeding season last year and
between secondaries 7 and 8 as the two innermost tertials have been
replaced in its 1st prealternate molt this spring.
to Mark Habdas, Kerry Kenwood, Carol Matthews, Jason Jones, Debbie
Wheeler, Sarah Gray, Mike Nutter, Kyle Norris, Louise Routledge,
Monica Nugent, Sara Legros, Christine Bishop, Kathy Elwood, Rufus
Macintyre, Dev Manky, Marg Anderson, Cyril Chan, Ivand Pulido,
Kirsten Wilcox, Andrew Venning and Kelly
Palmer-McCarty for their help with spring banding - as always
VARC would not exist without the energy, enthusiasm and commitment
of our amazing volunteers!
Special thanks and photo credits to Debbie Wheeler, Mark Habdas and
Dev Manky for many of the photos appearing on VARC blogs and Images
of the Month many of which truly are stunning images!
Avian Research Centre Society is a Registered Canadian Charity (#
82118 2656 RR0001)
Donations to a registered charity are of course tax deductible and
we hope that people concerned about avian environmental issues in
Vancouver will consider making a donation to further VARC’s work.
This can be done by simply clicking on the link below to make an
immediate donation. Thank you for your generous support – it really
is very much appreciated!