Vancouver Avian Research Centre

.....Research - Conservation - Education
Spring 2013 - 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 north-west!

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!

The first 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 second year (SY) males do not have the brilliant red epaulettes (lesser coverts) of adult (ASY) birds.

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).

The 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!
Tree Swallows (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 CP.

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. 

With 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 feathers.

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 prealternate feathers.

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 May Image 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 in Mexico!

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 the gorget.

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.

Hummingbirds are 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 RUHU below.

One RUHU male had us scratching our heads wondering if it could possibly be a male Allen's Hummingbird (ALHU)!

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 viewed here:

http://birdvancouver.com/testimonials_id.html

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!

That 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 2011 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.
We also talked previously about 'brown' Purple Finches (in our May Blog 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 raspberry juice'!

 

 

 

Savannah Sparrows (SAVS) returned to the park their loud, buzzy, insect like song resonating around the old field habitat where we band.

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 birds.

 

 

 

 

 

The 1st prebasic molt is partial in SAVS and usually includes all median and greater coverts and 1-3 tertials.

The prealternate molt includes no greater coverts, usually 1-3 tertials and occasionally central rectrices.

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 blue arrows).

 

 

 

 

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 and nest.

 
 

 

 

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, (lutescens), 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 (September 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 - you choose!!

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%.

And 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 banders!

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 station!

Molt answer: 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.

Thanks 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!

The Vancouver Avian Research Centre Society is a Registered Canadian Charity (# 82118 2656 RR0001)

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