Vancouver Avian Research Centre

.....Research - Conservation - Education

July - Banding activity in early July slows down as migrants have all moved through and most of our breeding birds are either on territory or incubating eggs. Dawn in the park allows for some stunning photo opportunities as the mist rises over the old field habitat where we band.

One thing that definitely doesn't slow down is the grass which seems to grow while you watch it and which presents a bit of a problem for our 'vertically challenged' volunteers like Celia who literally disappear in the grass and have to be sent out with walkie-talkies to make sure we can find them!

In addition to being a good time to study the molts and plumages of local breeding species July is an exciting time for banders as it produces a wide array of plumages, from juvenal to fresh first basic, to worn alternate, through the various sequences of molt leading to fresh definitive basic (i.e. fall/winter non-breeding) plumage.

A very large part of our banding activities involve accurately ageing and sexing the birds we catch in order to determine population dynamics in terms of the changes in size and age composition of avian populations and the biological and environmental processes influencing those changes. A complete understanding of the timing, sequence and extent of molt is essential to the accurate ageing and sexing of birds in the hand always remembering that young males look a lot like adult females.

In many species the prebasic molt is the only molt occurring annually thus breeding occurs in the birds basic, winter non-breeding plumage. But in many species of passerines there is a second molt that occurs prior to the next prebasic molt - called the prealternate molt it occurs in both first year birds and adults during the late winter / early spring. In spring and summer first year birds can show three generations of feathers but adults can also show molt limits! An example and explanation of this is given below on this second year (SY) female Yellow Warbler.

During its first prebasic molt last fall, this bird replaced 8 inner greater coverts, the carpal covert and greater alula covert, then stopped molting. The first molt limits therefore (indicated with red arrows numbered 1) are the molt limits between GCs 2 and 3, between the carpal covert (CC) and retained juvenal primary coverts and between the greater alula covert (A1) and the adjacent larger alula feather (A2) all replaced in the 1st prebasic molt after the breeding season last year.

Many Dendroica (or should I say ex-Dendroica now they fall in the new Setophaga classification!) warblers (both adults and young) undergo a second molt in the late winter / early spring prior to the next prebasic molt called the prealternate molt. This results in a SECOND molt limit in the spring and, ultimately, three generations of feathers on a second year (SY) bird.  Here greater coverts 5-10 were molted this spring i.e. the prealternate molt limit is between GC 5 and 6 (indicated with red arrow numbered 2).  Thus the three generations of feathers are: GC 5-10 which are first alternate feathers i.e. the most recently molted feathers from the prealternate molt this spring; GC 1 and 2, the carpal covert and greater alula covert which are first basic feathers i.e. retained feathers from the first prebasic molt last fall; and finally, the two larger alula feathers, primary coverts, and primaries and visible secondaries (not including tertials) which are retained juvenal feathers.
Note also how the retained juvenal feathers, particularly the primaries are very worn and abraded now being close to 12 months old and having been worn for one long Neotropical migration and for an entire breeding season (indicated with red arrow 3)

And they say this molt stuff is complicated!!

We band a number of Northern Flickers each year at Colony Farm and love their handsome scalloped plumage and the bright red malars of males which are lacking in females like the one in the photo below left. Like other woodpeckers Flickers have very pointed and stiff retrices or tail feathers (photo below right) which are used to support them as they hitch their way up the trunks of trees. Unlike many other woodpeckers Flickers prefer to find food on the ground eating mainly ants and beetles which they dig up using their unusual slightly decurved bills.

Molt in non-passerines like woodpeckers is quite different from passerines.

Following their first prebasic molt, hatching year (HY) woodpeckers retain all of their juvenal primary coverts. Second year (SY) birds have all juvenal primary coverts until their second prebasic molt, when they replace up to several outer juvenal primary coverts. Until their third prebasic molt in their third year, third year (TY) birds therefore show two distinct generations of primary coverts - very worn and often abraded juvenal inner primary coverts and fresher replaced second basic outer coverts.
This was the case with the above female (wing photo below) showing replaced outer primary coverts from the birds second prebasic molt last year now making her a third year (TY) bird.

During their third prebasic molt, TY woodpeckers normally replace most if not all of their primary coverts and at this molt any retained juvenal coverts will almost always be replaced.

Conversely these hatching year Downy Woodpeckers (DOWOs) were in full juvenal plumage, the male (photo above right) showing an extensive red juvenal crown patch. Peter Pyle's excellent book the  Identification Guide to North American Birds Part I suggests that both male and female DOWO juveniles have a red juvenal crown but it has been proven that DOWOs with an extensively red juvenal crown are, in fact, males, while those with a black, or mostly black,  juvenal crown are young females (photo below right). The same is apparently true of Hairy Woodpeckers.

During this males first prebasic molt, its red juvenal crown will be lost and a red nuchal patch (on the back of the head) characteristic of 'adult' males will molt in.

 

Despite quiet and vacant boxes being available along the edge of the old field habitat one pair of Tree Swallows chose the box under the eaves of our Banding Pagoda to nest and despite the comings and goings of banding personnel, film crews and lots of visitors produced 5 nestlings.

The adults kept us amused with their constant scolding every time we entered the Pagoda and the nestlings kept us all entertained as we monitored their progress from impossibly tiny nestlings to 10 day olds (photo top left below) ready for banding and then watched as first beaks then heads appeared at the entrance hole until they finally fledged at 19 days (photo below right)

Swallows are part of the guild of aerial insectivores which have suffered precipitous declines and their plight has gained increasing attention. Research has shown that in the last 20 years the population of Barn Swallow and Bank Swallow has fallen by 70% and Cliff Swallow, Northern Rough-winged Swallow and Purple Martin by over 50%. Without solid insights into the mechanisms that are driving population changes, it is difficult to imagine how the current decline of aerial insectivores can be forestalled, let alone reversed. VARC’s banding data from 2010 showed a huge decline in the capture of swallow species and their numbers compared to 2009 which made our 2011 TRES babies even more special!

Speaking of the plight of aerial insectivores we were contacted by the Western Canada Wilderness Committee who wanted to film a documentary on Barn Swallows, a species of special concern in BC and a species upgraded to threatened in 2011 by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
Some serious equipment was brought in to photograph and film our swallows and the crew got some excellent shots and footage of adults and nestlings at various stages of development.

Following their filming sessions they pitched the story to Global TV who in turn came out to film and interview and the story was aired on Global TV News Hour on July 22nd!

Our catch in July is dominated by hatch year birds in juvenal plumage. A definitive characteristic of juvenal plumage is loosely textured feathers. Juvenal feathers have many fewer interlocking barbules and, therefore, looser barbs, giving them a very wispy appearance.

This is especially noticeable on the nape and back feathers, and also on the undertail coverts, as shown in the photo (below right) of this hatch year Black-capped Chickadee.

This hatch year (HY) Song Sparrow showed all of the characteristics of a bird in juvenal plumage - the streaked, spotted plumage, dull eye colour and prominent gape. In addition the feathers of the tibiotarsus (photo below right) and underwing (photo below left) develop later in juvenile birds and these areas are often devoid of feathers as can clearly be seen in these photos.

More characteristics of juvenile birds are displayed by this hatching year Savannah Sparrow showing very buffy plumage, a prominent, fleshy, brightly coloured gape, a nesting trait often retained for several weeks following fledging and bright mouth lining.

Eye color is another useful criterion for ageing certain species and has been mentioned in previous blogs. It's especially useful for those species with dark or brightly colored eyes as adults. In these species the eye color of the juveniles usually is duller and browner or grayer than that of adults.

This characteristic is shown in this locally hatched Ring-necked Pheasant which was flushed one morning while making our net rounds. As we are not able to band game birds we ran back to the banding station for a camera, took a few quick photographs and released this baby which ran off to join its scolding Mother. Although somewhat prehistoric looking it drew lots of oohs and ahhs from the banding team!

More gratuitous baby photos - Common Yellowthroat (top left), Orange-crowned Warbler (top right), Spotted Towhee (bottom left) and Cedar Waxwing (bottom right)
Two hatch year wrens were a surprise for us this month as neither species would readily be associated with the old field habitat where we band proving once again the value of this unique habitat. We'll leave it to you to guess the identity of these two species, one of which was a new species banded for the site! (Answers at the end of the blog!)
We are very fortunate to have a banding station in the heart of an urban area like Vancouver as it affords us the luxury of lots of visitors which gives us an opportunity to talk about the importance of preserving habitat for breeding and migratory birds.

In addition to using birds in the hand as teaching tools to raise awareness of environmental issues we teach visitors how to hold a bird gently in the 'banders grip' which is a unique experience and one they will never forget. We've always said that once you place a songbird in to anyone's hand you have a convert for life and that can clearly be seen in the faces of a couple of our visitors this month!
That is especially true of children and we have lots of kids visit us and love their energy and enthusiasm for birds and that was certainly the case with 10 year old Lily who visited with her Mum.

Both Tree Swallow nestling and Lily scored a 10 on the cuteness scale!

Some 20 plus kids from the Catching the Spirit youth group came out to learn more about the birds and habitats of the Vancouver area.
Catching the Spirit is an outdoor environmental stewardship and learning program that encourages leadership development and social responsibility for youth in the Metro Vancouver area.
Everyone had a great time and said that the trip to the banding station was the highlight of their weekend!
This gorgeous second year (SY) female Eastern Kingbird was a first banded for the season. Molt is not well known in this Tyrant Flycatcher and Pyle indicates more study is needed. This bird showed an incomplete 'eccentric' 1st prebasic molt pattern with retained primaries 1-3 and a clear molt limit between the replaced greater alula covert (A1) and retained alula feathers (A2 & A3).

EAKIs are sexually monomorphic both male and females show the bright red crown patch (which are normally concealed) shown in the photo above left.
The shape of the outer primary P10 (indicated by the red arrow in photo on the left) is helpful in separating males from females (and juveniles from adults) the indentation on the inner web of the feather (called a notch) being shorter in adult females than adult males.
Our female EAKI also had a fully developed brood patch leaving us in no doubt as to her sex.

By the middle of the month many hatch year birds have already started their first prebasic molt. The juvenal plumage of many wood warblers, like this very recently fledged Orange-crowned Warbler replaces the juvenal plumage within just a few weeks after fledging.
 

This second year (SY) male Lazuli Bunting pleased one of our volunteers Mum's who came for a visit - she wanted a 'Bluebird' and although it's a bit late in the season for Mountain Bluebirds we did manage this beautiful 'blue bird' a second year (SY) male showing clear molt limits between retained and replaced feathers.

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.

And finally an enormous thank you to Saskia Wischnewski who left us to return home to Germany before heading back to university in  Scotland to continue her studies. Saskia was such a great addition to the banding team for the past 9 months and we'll really miss her. Make sure you keep in touch Sask!

Thanks to Mark Habdas, Kerry Kenwood, Carol Matthews, Jason Jones, Saskia Wischnewski, Marg Anderson, Jerry Rolls, Debbie Wheeler, Sarah Gray, Marguerite Sans, Marianne Dawson, Mike Nutter and Gabriel Jamie for their help with banding this month.

Answer: Bewick's Wren (left photo) MARSH WREN (right photo) Marsh Wren was the new species banded for the site. Although common in the tall reeds of the pond adjacent to the banding area this secretive and difficult to see wren rarely strays in to the old field habitat where our nets are located.

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