Vancouver Avian Research Centre

.....Research - Conservation - Education
Fall 2017

Fall is our busiest time at Colony Farm as dispersing hatch year birds flood through the park. On some mornings the grass was literally alive with birds as we drove in to the station and on those days, we knew we were in for a busy morning.

Depending on the availability of trained personnel and to ensure bird safety and welfare according to our banding station protocol, not all of our nets may be deployed on these mornings to make sure we are not overrun with birds!

Sparrows, sparrows and more sparrows!

The old agricultural fields are ideal habitat for a range of western North American sparrows including American Tree, Brewer’s, Chipping, Clay-colored, Swamp, Vesper, Savannah Grasshopper, Fox, Song, Lincoln’s, White-crowned, Golden-crowned and White-throated all of which have been banded or recorded in the park.

In late summer, sparrows make up the majority of our captures and during this time we are  inundated with Song, Fox and Lincoln's Sparrows. Most of these birds are hatch year birds in either juvenal or formative plumage and we are always on the lookout for uncommon or rare species than can easily be mistaken for common ones!

A good example of this is juvenile Swamp and Song Sparrows which can look nearly identical. With practice they can be quickly identified by looking at the difference in their bill morphology. The Swamp Sparrow (photo right bottom) has a thin, pointed bill compared to the wider and chunkier looking bill of the Song Sparrow above.

Swamp Sparrow also has the yellowish gape flanges, and less distinct submalar streak.

Once these birds undergo their preformative molt they will be easily distinguishable by their plumage alone.

Swamp Sparrows can also be confused with Lincoln's Sparrows at first glance.

Breeding adult male Swamp Sparrows usually have a bright reddish brown cap and are pretty unmistakable. However, as the photo left shows, the bird on the right is more likely a female and is quite similar to the Lincoln's Sparrow on the left.

In all plumages, Swamp Sparrows (below right) have darker more rust colored back streaking and a muddy whitish wash on the breast. Lincoln's Sparrow (below left) has a buffy wash on the breast and sides and is also very finely streaked.

Chipping Sparrows are another confusing late summer sparrow when they are in juvenal plumage, the hatch year bird below showing none of the distinctive field marks of it's adult counterpart (inset photo). The same applies to Brewer's, Clay-colored and Savannah Sparrows in juvenal plumage.

All of this means that in the late summer especially, for banders and birders alike, sparrows need to be checked closely to ensure the correct identification!

And this hatch year Song Sparrow had us doing a momentary double take given it's tiny size and overall very gray appearance. On closer examination we decided we couldn't make it in to anything else and concluded it was just an aberrant Song Sparrow!

Song Sparrows, like other Spizella and Melospiza sparrows, can have very extensive preformative molts including not just contour feathers but flight feathers (primaries, secondaries and retrices) as well.
Song Sparrows are among the Emberizid family which often show an alula covert (A1) molt limit. This can often be very subtle as the alula covert is a tiny feather, but there was no doubt with this bird as the alula covert was still in sheath - a molt limit in the making!

The hatch year (HY) Song Sparrow below was also completing its preformative molt, this one replacing lesser, median, greater coverts, all three tertials and all three alula feathers. Primary coverts are always retained juvenal feathers in all these examples of partial preformative molts.

On the theme of Sparrows, among the dozens of Sooty Fox Sparrows we had THREE Red Fox Sparrows!

There are four groups of Fox Sparrows, each group having a distinct natural history. The form most commonly seen along coastal south-western British Columbia is Sooty Fox Sparrow, Red Fox Sparrow breeds much further north and most winter east of the Great Plains and are rare in the Vancouver area.

Red Fox Sparrow (photos above and right) has a mixture of gray and rust in the crown, dull grayish supercilium, rufous auriculars and much more rusty brown on the back. The tail, upper tail coverts and rump are bright rusty brown.

As can be seen in the photo below of side by side birds, Sooty Fox Sparrow has a uniformly dark brown crown, dark brown nape and mantle, brown wings and scapulars. The chin and throat is whitish flecked with brown and breast with heavily triangular shaped dark brown spots.


Next up was one of three hatch year (HY) White-throated Sparrows, an annual but uncommon winter visitor for us, this  tan-striped individual showing the tan-coloured head stripes versus the white head stripes of the white-striped form.

Molt limits in Zonotrichia sparrows can be tricky given the strong colour contrasts in the greater coverts. These so called 'pseudolimits' simulate a molt limit so close attention must be paid to wear to the tips of feathers to distinguish a replaced from a retained feather.

On this wing of the HY bird above, there is an obvious molt limit within the greater coverts with the innermost GC's replaced but at first glance the eye can be drawn to the more prominently rusty-edged inner greater coverts GCs 8 & 9 (green arrows) whereas the molt limit is, in fact, between GC6 (retained) and 7 (replaced).

In these partial preformative molts rectrices are generally not replaced so tail feathers are retained juvenal feathers. The tail of the same bird shows the narrow, tapered shape of the outer rectrices typical of first year birds, some of these already showing wear to the tips.

And another Zonotrichia sparrow, this time a hatch year (HY) Golden-crowned Sparrow still showing a prominent gape.

And again, the wing of the same bird showing the true molt limit within the greater coverts (red arrow) and the pseudolimit of the more richly edged inner greater coverts (green arrows).

The feathers absorbing the brunt of the exposure to the elements are the tertials and the coverts, in particular the greater coverts. Similarly, in the tail, the central pair serve as a protective covering for the remaining rectrices. Central rectrices are bilaterally symmetrical and are raised above the plane of attachment of the remaining rectrices ensuring that they cover the closed tail.

Because of the protection they provide for the remaining flight feathers and because of their extreme exposure to wear, the tertials and central rectrices are the only flight feathers likely to be included in partial preformative molts. As can be seen in the photo below, the central rectrices of this Golden-crowned Sparrow are already showing extreme wear to the tips.

So, with all this talk of sparrows and tricky sparrow identification in the late summer, we thought it was time for an ID challenge - can you identify the mystery sparrow below?

Our new Bird Identification Workshop was a big hit with 21 people participating in the weekend course. Building on VARC’s present, popular workshop we added four further field trips on the following four subsequent weekends. The field trips are being led by Yousif Attia and Jason Jones, two locally recognized bird ID experts who are helping workshop participants build on the skills they learned during the weekend course.

Fall offers a great learning experience in the lower mainland with birds in tricky juvenal, formative and basic plumages and with Yousif and Jason leading the ongoing field trips, identification of the more difficult groups such as shorebirds, raptors and gulls is also being tackled for more advanced birders!

VARC volunteers Shae Turner and Martine Cutbill were also busy hosting our schools program at SPCA kid's camps throughout the Lower Mainland during the summer holidays.

And visitors during September included Sav and Jody Saville on their way back home to New Zealand from attending the British Birdwatching Fair. Sav is a very experienced birder and bird guide who runs Wrybill Birding Tours in New Zealand. Born in London he was an active part of the British twitching scene and an eye-witness to the infamous Reading Sewage Farm Black-winged Pratincole incident. He moved to New Zealand in 1989 and has since gained notoriety there being a key player in the rediscovery of the supposedly-extinct New Zealand Storm-petrel, being on the trip in January 2003 when the species was initially resighted, and being the first person onboard to see the bird! Shame he's a Tottenham supporter really!

As the alpha code for Savannah Sparrow is SAVS, we couldn't resist the photo (below right) of Sav with a SAVS!

Late summer is always an exciting time for molt addicts as many birds are in heavy molt. This hatch year (HY) Swainson's Thrush is undertaking its preformative molt with molt limits in the making with median coverts and the inner greater covert in sheath. Notice the olive edged emerging inner greater covert and buffy fringes on the retained juvenal outer greater coverts (red arrows).

We had a whole discussion at the banding station one day as to if we could live somewhere that doesn't have hummingbirds and the consensus was simply no! We are fortunate to have hummingbirds all year round in Vancouver with our resident Anna's like this hatch year male, remaining during the winter long after our migrant Rufous have headed south to overwinter in Mexico.

A trickle of late departing wood warblers came through including this beautiful hatch year (HY) female Townsend's warbler.

Orange-crowned Warblers are part of the genus Oreothlypis, warblers with sharp, pointed bills which eat mainly invertebrate prey, including insects, spiders and caterpillars. They use their sharp, pointed bills to prise open buds to extract small insects and spiders and to pierce the bases of flowers to extract nectar. If gentle pressure is applied to the upper and lower mandible, a reflex action will sometimes cause them to prise open fingers in the same way!

Steller's Jays are common birds in the Vancouver area but uncommon for us preferring coniferous forests to the old field habitat where we band, so this hatch year bird still showing a prominent gape was a nice addition to species diversity at the station.

Varied Thrushes are also common but shy and hard to see in the humid evergreen forests of the pacific north-west where they breed. In winter, some move in to dense parks and gardens but rarely in to the old fields where we band so the odd one we catch like this hatch year male is always a special treat as they have to be our most stunning resident bird!

The preformative molt in Varied Thrushes is partial with molt limits occurring within the greater coverts, this male showing a clear limit between the replaced and bluish-grey edged inner greater coverts and 5 retained outer greater coverts (red arrow).

So ends another season at VARC, our ninth season of monitoring and banding at Colony Farm.

2018 is already shaping up to be an exciting year when we are planning to host the first North American Banding Council (NABC) certification session at VARC in the spring.

We are also excited to be an active participant in the 27th International Ornithological Congress 2018 which will be held in Vancouver (19-26 August, 2018). IOCongress2018 is a game-changer by combining the prestige of hosting the 27th International Ornithological Congress with the City of Vancouver’s annual Bird Week, the organizers are creating the first ever World celebration of BIRDS in all their dimensions. Carol Matthews (VARC's Treasurer and Board Member) has been heavily involved in the organizational aspects of the Bird Fair and we look forward to welcoming you all to beautiful BC and Vancouver next August!

And last but not least, a massive thank you as always to all of the Friends of VARC who support our work, our sponsors and donors, visitors, workshop participants and of course all of the VARC volunteers who sacrifice their weekends and set alarms for unearthly hours during the summer months, mostly on their weekends off, to help with banding operations - thank you again and see you all in 2018!

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