is our busiest month of the year as the park fills with returning
migrants and dispersing juveniles beginning their southbound
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 assess the quality of sites
and/or habitats directly.
Many of the birds
we band have large fat loads either initially or on their stopovers
here which typically last from as little as a few days to as much as
a week or more. The ability of migrants to deposit fat sufficient to
fuel at least one whole night's migration is critical to their
survival and to their long migrations to and from the Neotropics.
Fat is accumulated
on a bird in three areas; the furculum (the area between the fused
clavicles – the so-called wishbone), the wingpits and abdomen (see
graphic below left). Each bird caught for banding is assessed for
fat by blowing the feathers of the throat to reveal the furculum and
scoring fat deposits on a scale of 0 - 5 (graphic showing
cross-section of furculum below right).
The photo below (A)
shows the hollow furculum of a Black-headed Grosbeak (BHGR) with no
fat deposits - The lean body mass of a bird like this is 38-40
grams. Photo (B) shows a maximally fattened BHGR with fat
overflowing the furculum and weighing 59 grams. Photo (C) shows the
fat laden wingpit and photo (D) the fat laden abdomen of the same
bird. Our record was one BHGR weighing in at a mighty 72.2 grams!
Migrants like these
can double their lean body mass and the caloric density of this
amount of fat is easily sufficient to sustain the energy demands of
birds making non-stop nocturnal flights of maybe 700 kms or more and
this of course is just one of several such flights these birds need
to make to take them from their North American breeding grounds to
their central and south American winter grounds.
The high insect and
fruit production in late summer at Colony Farm provides an ideal
environment for these birds to deposit fat sufficient to sustain the
energy demands for southward migration and the VARC study has
provided compelling evidence of the value of the old field habitat
in the park where a fat depleted migrant can rapidly meet its
2011 has certainly
been a fantastic year for visitors and we've received lots of media
attention too with SHAW TV the latest station to come
out to film the banding and talk to us about avian and ecosystem
conservation. The show was aired on 'The Express' their human
interest magazine program and can be viewed by clicking here:
Shaw TV Video
This was the third
film crew out this year and we're getting used to the media
spotlight - this year Global and Shaw TV stations, next year 'Hello
visitors we welcomed Tim Ball a British 'A' Ringer and Trainer from
the Reading and Basingstoke Ringing Group.
It's always great
to have experienced visiting ringers and banders especially when
they bring Cadbury's Boost Bars!
inexplicable reason we didn't get a photo of Tim but did get this
photo of his life MacGillivray's Warbler and 'ringing tick'
Thanks for your
help Tim - it’s always great to have another Brit around with a
decent sense of humour!!!
The two warblers below show how
similar some warblers look in basic plumage especially when they are
females. The bird on the left with the split eye ring formerly of
the genus Oporornis now of the genus Geothlypis and
the bird on the right with the full eye ring formerly of the genus
Vermivora and now of the genus Oreothlypis.
Getting used to the new scientific names is a challenge for many
birders and banders and for some of us Dendroica Warblers
will always be just that even though we've started the long process
of trying to say goodbye! Still it's fascinating to see how our
knowledge of these birds continues to develop and who would've
guessed that American Redstart was related to Hooded Warbler?!
Both of these birds were hatching year
(HY) females showing molt limits between the replaced outer greater
coverts and retained inner primary coverts (illustrated on the
corresponding photo below each bird with a red arrow)
If you don't know your
from your Oreothlypis the answers to these birds identities
are at the end of the blog!
Our final Bird
Monitoring and Banding Workshop of the year was held the weekend of
the 9th - 11th and a great group of people enjoyed not only fabulous
weather but lots of birds and good species diversity. Everyone had a
great time and all agreed they had become banding and molt converts!
It really is
amazing to see people progress from little or no knowledge when we
meet at lunchtime on the Friday afternoon to having extensive
knowledge by the end of the weekend. Thank you to all of our
workshop participants and especially for their extremely kind and
generous course evaluations which can be seen on our
|Our workshops could
never be the success they are without the help of all of our
volunteers like Jerry here pointing out (I think!!) that there were
still two more birds for processing!!! Nice outfit Jerry - you'll
make someone a wonderful wife!!
came through in good numbers this month and although noisy and
aggressive in the hand are one of our favourite late summer species.
The 1st prebasic molt in this species usually includes all lesser
and median coverts and none or as with this bird below just a single
inner greater covert (indicated with red arrows in the photo below
right). Very bright hatch year males like this can be separated from
females by the extensive yellowish tips to the blackish median
coverts and by their bright yellow rumps and throats.
Many of the birds
we band in early September are still in juvenal plumage showing all
the characteristics of recently fledged birds like this hatching
year (HY) Black-headed Grosbeak (photo left) with prominent gape and
the hatching year (HY) Eastern Kingbird (photo below left) with very
bright mouth lining.
We discussed the
shape of the outermost
primary (P10) in EAKIs
in the July Blog being helpful in separating males from females and
juveniles from adults. The indentation or notch on the inner web of
this feather is shorter in adult females than adult males and
lacking on juveniles as can be seen in the photo below right.
Empidonax flycatchers like this hatch year (HY) Willow
Flycatcher the prebasic molt occurs on the winter grounds so HY wing
feathers are fresh looking having just grown in this summer.
An adult bird now carrying 6-8 month old feathers that have been
used for one long distance migration, and which have been worn for
an entire breeding season show extensive wear.
Fresh wing bars (edged or tipped median and greater coverts) of HY
Empidonax flycatchers are buffy/yellow in appearance like this
bird, not whitish as in adults.
The exception to this rule is Hammond's Flycatcher which is the only
Empid molting flight feathers on its breeding grounds.
Continuing with the
theme of Tyrant flycatchers in juvenile plumage this one
could easily be confused in the field lacking the obvious smudged
coverts of its adult counterpart. Answer at the
end of the blog.
Two more confusing
hatch year (HY) Empids with brownish washed upperparts and
buffy wing bars - Willow Flycatcher in the background and
Pacific-slope Flycatcher in the foreground.
And a final
confusing Empid this time one of the two species with grey
heads, grey throats, yellowish bellies and almond shaped eyerings
but this one with the long tail, short wing and where
shorter than P4 - a hatch year (HY) Dusky
is the first late summer/fall DUFL we have caught at Colony Farm all
the other birds being spring captures.
Contrary to all these hatch year birds
in fresh juvenile or first basic plumages, many adult birds coming
to the end of the breeding season are now showing very worn feathers
indeed like this after hatch year (AHY) female Common Yellowthroat.
This bird with a receding brood patch (photo below left) was showing
very worn flight feathers (remiges and retrices).
Feathers are dead
structures like human hair or nails and damaged or worn feathers
cannot be replaced until the annual molt cycle. Very worn feathers
like these show just how important the annual prebasic molt is
especially for birds undertaking long Neotropical migrations.
The 1st prebasic
molt in Savannah Sparrows (SAVS) is partial and usually includes all
lesser, median and greater coverts, usually 1-3 tertials but
according to Pyle no retrices.
These photos show the wing of a hatch year (HY) SAVS which had
replaced all lesser, median and greater coverts (the molt limit
shown above right between the outer GC and inner PC), the two
innermost tertials (S8 & S9) but we find that with our Pacific
coastal subspecies that central retrices are indeed often replaced
as can be seen in the photo right.
(WAVI) also appeared in good numbers this month like this handsome
hatch year bird of unknown sex.
We always look closely at WAVIs hoping
for the possibility of a Philadelphia Vireo (PHVI) which only breed
much farther north in north-eastern BC and are rare in the Vancouver
have a buttery yellow wash to the breast and a more distinct facial
pattern some of our bright WAVIs have us hoping.
maybe fortunately!) there is no mistaking the two species in the
hand as WAVI has a vestigial primary 10 (P10) shown with a red arrow
in the photo left. In PHVIs this feather is so reduced as to be
Still we'll keep trying!!
And finally this
hatch year (HY) Winter Wren - OK then Pacific Wren (in England it's
just called 'The Wren' Troglodytes troglodytes even though
we've changed the name of our one to Troglodytes pacificus!)
was another good 'get' for us this month being very uncommon in the
old field habitat where we band preferring coniferous forests with
fallen logs which provide ideal nesting sites for these tiny cavity
So that's about it
for our penultimate blog of the year - I'm off on a short birding
trip to Mallorca, Spain to catch up on migration in Europe and to
brush up on my European bird ID skills and to hopefully see
Eleonora's Falcon (Falco eleonorae) which delays its breeding season
in late summer to time it with the arrival of migrating birds which
pass through the Mediterranean islands at this time of year.
Thanks to Mark Habdas, Kerry Kenwood, Carol Matthews, Jason Jones,
Marg Anderson, Jerry Rolls, Debbie Wheeler, Sarah Gray, Olga
Lansdorp, Kyle Norris, Celia Chui, Mike Nutter, and Tim Ball for
their help with banding this month.
1. The Geothlypis warbler
on the left is MacGillivray's Warbler and the Oreothlypis
warbler on the right is Nashville Warbler.
2. The Tyrant Flycatcher above is a