had to happen and after 3 months of picture perfect weather in
Vancouver the rain came and came intensely severely hampering the
banding effort for much of the month!
The highlight of
the month was the addition of our new J-Trap - a 2.5 meter square
walk in ground trap. The main function of this trap is for our 2013
special species study on Band-tailed Pigeons.
Little is known
about the demographics of band-tailed pigeon populations because
their habits and habitat make it impractical to locate and observe
or trap an adequate sample of birds and monitoring information about
population status is presently limited to annual estimates of
relative abundance through the harvesting of birds primarily in the
US. However, in the early 1970s the total population size was
approximately at 2.9-7.1 million birds in the Pacific Coast region
(estimated primarily from harvest reports) and has shown a
consistent decline in the species occurrence.
The single greatest challenge in the monitoring and management of
band-tailed pigeon populations is the lack of reliable information
on population abundance. Existing surveys for this species provide
only trends in abundance and no information about absolute
Band-tailed pigeons inhabit coniferous forests primarily and are
highly mobile habitat generalists often traveling long distances (up
to 50 kilometers) to feed and drink. Their diet includes buds,
flowers and fruits of deciduous trees and shrubs especially oak,
madrone, elder, dogwood, cherry, cascara and huckleberry and large
numbers (flocks of 100 individuals or more) regularly frequent the
Park to feed on the elderberry fruit. This abundance within the Park
suggests that habitats within the Park are of high relative value to
this species in the Greater Vancouver area.
VARC's long term monitoring research will attempt to provide data to
assess demographic and population size of Band-tailed Pigeons in the
Park using geo-locator studies and by fully documenting biometric
measurements, molt sequences and feather color and pattern related
to age and gender of each bird trapped for banding.
Needless to say the
trap was an enormous amount of work in both the design and
construction and special thanks goes to Steve Howard (carpenter
extraordinaire), Kyle Norris, Mike Nutter, Todd Heakes, Ivand Pulido
and Debbie Wheeler who was the only one who was small and light
enough to crawl along the funnel to attach the hinged door to the
trap will also be used during normal banding operations and has
already been highly productive for many species of emberizids
which make up the bulk of captures during fall and winter banding.
neotropical migrants had already sensibly left us for warmer, drier
climes but some short distance migrants were still moving through
the park like this hatch year (HY) female Yellow-rumped (Audubon's)
The 1st prebasic molt in AUWA is partial and usually includes all
median and greater coverts and often the greater alula. This bird
however had replaced all median coverts, the carpal covert and
greater alula covert A1 (all marked with red arrows in the photo
below right) but had retained all of the greater coverts and main
lower alula feathers.
The contrast between the the replaced greater alula covert (A1) and
lower main alula feather (A2) can clearly be seen on the closed wing
of the bird (photo below left).
|This likely late
hatching Marsh Wren (MAWR) was still in the midst of its 1st
prebasic molt replacing all of it's greater coverts and carpal
MAWRs are uncommon for us in the old
field habitat where we band as these small, secretive wrens are most
often found in tall reed beds or marshes.
Interestingly we have only ever caught hatch year birds as they
disperse away from the reed bed at the pond adjacent to the banding
station where they breed. It may be that adult birds will only use
the preferred habitats of reed beds and marshes as they begin
||The 1st prebasic
molt in House Finches is extremely variable and can be complete in
some instances meaning hatch year birds replace all body and flight
feathers so at this time of the year many birds are aged simply as
In others like this
hatch year bird below the 1st PB is incomplete this bird having
replaced all of its lesser, median and greater coverts, the carpal
covert, all three alula feathers and the outer primaries and inner
secondaries forming the 'eccentric' pattern seen in the photo left
with the only retained feathers being the primary coverts and
remiges between the red arrows.
is particularly useful for aging NA landbirds in the hand in the
winter and spring after birds have completed skull pneumatization
(ossification) but there are other helpful indicators to age such as
eye colour being duller and browner/grayer in first year birds and
brighter/richer in adults.
One species where both eye colour and molt are very obvious is
Spotted Towhee (SPTO) and males of this species provide very useful
examples of eye colour and molt limits for trainee banders learning
The eye colour of the adult male (below left) shows the
characteristic bright red iris of an adult bird compared to the much
duller, browner iris of the hatch year male on the right. Also
notice the hatch year bird is showing a soft, flesh coloured gape
flange (the area at the base of the beak where the two mandible
meet) which will disappear and no longer be visible when the bird
becomes an adult.
Male SPTOs also provide 'smack you in
the face' molt limits for banders learning ageing techniques using
molt and plumage criteria. The adult male wing (below left) showing
what a quintessential adult wing looks like in the fall with jet
black remiges and no discernible molt limits. Also notice the
glossy, black rachises on the remiges of the adult bird with little
or no wear to these feathers.
Contrast that to the hatch year male (below right) with a very
obvious molt limit between the replaced lesser, median, great
coverts and carpal covert and retained primary coverts and replaced
tertials and retained primaries and secondaries. Notice here that
the rachises of the retained primaries and secondaries are matt not
glossy and dark brown not jet black and these poorly structured
juvenile feathers are already showing signs of extreme wear to the
And finally the retrices of the adult
bird (below left) are broad, truncate with little wear compared to
the thinner more tapered retrices of the hatch year bird right which
again are showing lots of wear to the tips.
Notice also the amount of white on R4 of the hatch year bird
(indicated with the red arrow) being much less extensive than on the
So there you have it ageing SPTO 101 in the fall with (hopefully!)
smack you in the face examples of ageing techniques!
anywhere near as obvious and far more subtle are the molt limits in
the wing of this hatch year (HY) Fox Sparrow (FOSP)
As FOSP are one of our most
abundant birds in the fall they are one of our special study species
where we are examining molt more closely to better understand the
extent of the 1st prebasic molt in the coastal northwest Sooty
According to the Identification Guide to North American Birds (Part
1) by Peter Pyle the 1st prebasic molt in FOSP usually includes all
median and greater coverts (rarely 1-2 outer GCs can be retained)
and no tertials or retrices.
Our research on FOSP caught for banding at Colony Farm shows that
the 1st prebasic molt on most birds of the Sooty Group is far less
extensive as the wing below shows.
This bird had molted GCs 8 and 9 only (the smallest innermost CG10
only partially visible is likely not molted) and oddly given the
unextensive extent of molt in the GCs, likely had replaced the
innermost tertial (S9). The median and lesser coverts appear to be
mixed molted and unmolted feathers.
We consulted with our friend and molt
Bob Mulvihill who agreed
with our age determination and looked at his notes for a dozen
eastern FOSP from Powdermill, and most had molted all of their
greater coverts and the carpal covert; a few also molted the greater
alula covert (A1), and just one single bird had retained 5 juvenile
outer greater coverts so it would appear from our research so far
that the 1st PB of FOSP in the Sooty Group is less extensive than
|This same bird had
a very conspicuous light-colored feather growth bar near the tip of
its tail suggesting that it was probably not well fed for one day
after it fledged from its nest.
Because the "fault" bar is near the tip of all the bird's rectrices,
it formed when the tail was just a short stub, which is the usual
length for most open cup nesting passerines when they leave the nest
at about 10 days of age.
Wing feathers develop more rapidly in nestlings, with recently
fledged birds typically having at least half grown wings. Although
incapable of sustained flight this enables them to leave the nest
where they are most vulnerable to predators.
The period of interrupted nutrition this bird suffered, evident as
the fault bar near the tip of the tail feathers, would, therefore,
show up much farther from the tips of the same bird's wing feathers.
Cold, wet weather in the spring may have played a role in making it
difficult for the parents of this FOSP to adequately provide for all
of their recently fledged young.
Extreme cases of unquestionably even fault barring like this can be
useful as an ageing criterion - juvenal wing and tail feathers are
grown concurrently, while adult wing and tail feathers ordinarily
are grown in a staggered pattern.
example of the FOSP above we mentioned that the innermost greater
covert (GC10) was likely an unmolted feather. When the 1st prebasic
molt is partial and songbirds replace less than all of their greater
coverts, the innermost (GC 10) is often a skipped (unmolted)
This is often the case with Dark-eyed Juncos, our Oregon Junco
(ORJU) below showing a clear molt limit between the retained
juvenile outer greater covert (GC1) and the molted inner greater
coverts (GCs 2-9) and the very obvious retained innermost greater
In species with partial 1st PBs where less than all GCs are replaced
it is always worth banders checking that innermost feather!
Hermit Thrushes (HETH) were caught for banding this month. HETH are
short distance migrants and the only catharus Thrush to
overwinter in Vancouver and to be regularly recorded on the
Christmas Bird Count (CBC).
Like all catharus thrushes aging HETH is relatively easy with
hatch birds (HY) often showing the buffy tear drops on retained
juvenile greater coverts mentioned in
previous blogs. The HY
HETH wing (below left) showing a clear molt limit between the
retained outer and replaced inner greater coverts (indicted with the
The shape of the tiny vestigial outer primary (P10) is also helpful
in determining age of catharus thrushes being narrower,
tapered and shorter than the primary coverts in adult birds and
broader, more rounded and longer in first year birds, often
extending beyond the primary coverts as in the photo below right.
|The VARC blog is
not a soapbox but some of the things we still see happening to
migratory birds in spite of migratory bird acts in most countries
leave you shaking your head in disbelief.
In the Northeast Indian state of Nagaland, tens of thousands of Amur
falcons are being trapped and slaughtered everyday during their
migration from Siberia to South Africa. In October this year, a
small group of conservationists were able to document this shocking
massacre and initiate specific action steps to try and stop the
killing. You can read their report and watch a video at this link:
Amur Falcon Slaughter
We received this on the same day that a report was released by a
scientist at the University of California, Berkeley which estimated
that 75% of all mammal species will have disappeared from this
planet in less than 300 years!
|On a lighter notes
the 2013 VARC calendar is now available with stunning images of some
of the birds banded during the 2012 season at Colony Farm.
The full calendar can be viewed and ordered online by clicking the
image right with all proceeds going towards VARC's public outreach
and and education programs for 2013.
really was an amazing year for VARC and we achieved a number of
significant milestones. With record numbers of visitors to the
banding station and extended public and community outeach which
included the addition of our schools and youth programs we were able
to considerably extend our educational reach.
We implemented a number of special projects and species studies in
addition to sustaining 4 days a week banding effort at the station
during spring and fall migration and during the breeding season.
This would not of course be possible without the help, dedication
and commitment of our growing band of volunteers who give freely of
their spare time during busy working lives, who instead of rewarding
themselves with long lie ins on their weekends off, set their alarm
clocks sometimes as early as 3.30 am during the summer months to
join as at the station for dawn. We can never express our gratitude
And finally, we would
like to thank all of our sponsors and friends of VARC for their
amazing financial support which allowed us to reach our fund raising
goals for 2012 and to continue our work to provide data and research
support that will allow for the safeguarding of bird habitats in the
Vancouver area. Thank you all!
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!