Vancouver Avian Research Centre

.....Research - Conservation - Education
Fall (August - October 2015)

I couldn't decide which one of Mark Habdas's stunning fall images to use to open the blog so I chose these 3 but please click on any of the images to see an index of some of his recent fall photographs - they really are amazing - Thanks Mark!

VARC was delighted to host the 2015 Western Bird Banding Association’s (WBBA) annual meeting from September 4th – 7th and an action-packed 4 days of banding, workshops, poster, plenary, scientific sessions and field trips were enjoyed by ornithologists from across Canada, the US and Latin America which was fitting given the meeting theme, Banding across Borders signifying the power of partnerships across cultures and countries to leverage the collective expertise of participants to affect bird science, conservation and land management.

Mark was again official photographer and after sorting through the hundreds of photos taken finally managed to whittle them down to a hundred or so which can be viewed by clicking on the image below!

Thanks to all of the conference participants, attendees, field trip leaders, workshop hosts, keynote and plenary speakers, scientific and poster session presenters and to all of the VARC volunteers who helped make this year’s conference such a success!
In addition to all the visitors there were also birds to band! This handsome hatch year (HY) male Black-throated Gray Warbler was likely of the Interior (halseii) subspecies based on size and showing very extensive white in the rectrices (photo below right) than is normal in the coastal subspecies (nigrescens).

The preformative molt is partial in this species with all lesser, median, greater coverts and carpal covert replaced the red arrow (photo below left) pointing to the molt limit between replaced outer greater coverts and retained primary coverts although it appeared that the greater alula covert (A1) had not been replaced in this individual. First year males can be separated from first year females by the mixed gray and black (rather than grayish) crown and auriculars, distinct black centers to the back feathers and usually by the median coverts with white tips usually without black shaft streaks although again this individual did show faint shaft streaks to the median coverts. An example of the prominent shaft streaks to the median coverts of first year females can be seen in this photo from our June 2011 blog (white arrow on this photo).

Gray Catbird is an uncommon species for us on the coast being much more common in the interior of BC although their secretive behaviour often makes them difficult to see. They belong to the genus Dumetella, which means “small thicket” and are usually found skulking in dense shrubs and thickets and not easily seen.

This hatch year (HY) bird of unknown sex was showing a clear molt limit between the fresher (and longer!) replaced inner greater coverts and retained, worn and brownish-grey outer greater coverts.

Notice also the retained innermost greater covert (GC 10). When songbirds replace less than all of their GCs in partial preformative molts, GC 10 is often a skipped feather!
 

Continuing the theme of uncommon species this hatch year (HY) Swamp Sparrow was a first for the station and species number 97 banded! Looking superficially similar to Lincoln's Sparrow in formative plumage but with a bolder streaked back pattern, plain breast, greyish nape and darker crown. As Lincoln's Sparrows appear in the park in their hundreds during fall migration uncommon sparrows such as this can be easily overlooked!

The preformative molt in this species includes all median and greater coverts and often 1-3 tertials; the molt limit below between the outer greater covert and inner primary covert and between the innermost tertials (S 8 & 9) and outermost tertial (S7) shown with red arrows (photo below left).

The very narrow, tapered and abraded rectrices typical of first year birds are shown in the photo below right.

And another uncommon species was this Tan-striped White-throated Sparrow. White-throated Sparrows show up in small numbers on the coast each fall and were unusually abundant this year with multiple sightings on some days.

White-throated Sparrows eat mainly seeds of grasses and weeds and the high insect, seed and fruit production in the park in the fall provides an ideal environment for migrant birds such as these to deposit fat to fuel the energy demands of long distance migrations.

Molt limits in Zonotrichia sparrows can be tricky given the strong colour contrasts in the greater coverts. These so called pseudolimits (blue arrow - photo left) simulate a molt limit but close examination of feather wear to the tips shows that these feathers are in fact the same generation and the molt limit is between the outer greater covert and inner primary covert and alula covert and lower alula feather as indicated by the red arrows.

  

Another good capture was this stunning hatch year (HY) Red-breasted Sapsucker. An inhabitant of coniferous and mixed forests of the northern Pacific Coast, they are rare in the old field habitat at Colony Farm where we band.

Although very bright, red birds like this one look like males but both sexes are in fact similar by plumage. We've talked in previous blogs about molt in non-passerines like Sapsuckers and how following their preformative molt, hatching year (HY) woodpeckers like this bird retain all of their juvenal primary coverts (photo below left).

Although not a new species for the station it was, as can be seen from the smile, a 'banding tick' for Sarah Legros!

A call from Orphaned Wildlife Association (O.W.L.) had us drop everything to go down to band a hatch year female Osprey which needed to be returned to the wild in time for migration.

She was found swimming in the water at Maplewood Flats Conservancy, a protected intertidal marsh on the north shore of Burrard Inlet in North Vancouver. Becoming waterlogged and exhausted she was rescued and taken to O.W.L. She was rehabbed on 'fat' live trout and in great shape when we released her back at Maplewood. Mark got these photos as she took off and flew strongly out in to the Burrard Inlet where the nest had been located on one of the old logging poles in the inlet.

Nice to have happy endings to these stories and another great example of what a fantastic job Martina and the crew at O.W.L do to care for all these raptors that simply wouldn't make it without them!

Osprey now have a dramatic presence in the Burrard Inlet which began in Spring 1991 when a single pair arrived from their wintering grounds in South America, built a nest on an old logging pole and raised two young, a success which they repeated the following year. Up to four pairs now return each summer to breed in the Inlet.

'Our' bird was later spotted alive and well and photographed fishing along the inlet - hopefully she'll make it back again to breed in North Van next year!

 

Another call when out, this time for emergency Bald Eagle banding when two kids found an eagle caught in a hanging Frisbee golf wire in a Burnaby park. The bird was again taken in to care at O.W.L. and quickly rehabbed before being banded and released in the park along with the CTV News team who were able to film the event.

Click on the image right to watch the video which made the CTV evening news!

 

Varied Thrushes are common along the Pacific Coast living in dark, wet, mature forests dominated by coastal redwood, Sitka spruce, red alder, western hemlock, western red cedar, western larch, or Douglas-fir.

Their main diet is insects in summer but in winter they switch to berries and seeds and are found in a broader range of habitats, including parks and riparian areas where fruit and berries are abundant. This likely explains why they appear in the old field habitat where we band during fall.

Varied Thrushes are sexually dimorphic, males (below right) having distinct, blackish breast bands while females (left) have indistinct brownish breast bands. Within each sex first year birds have less distinct breast bands than adult birds.

A sure sign of fall is the appearance of Dark-eyed Juncos in the park as these altitudinal migrants return to lower elevations for the winter.

This male Oregon Junco caught for banding had a sizeable tick which we were able to safely remove from below the birds eye. As might be expected, most ticks occur on ground-feeding birds like Juncos and there are several species of avian ticks some of which appear to infest only birds, while others spend parts of their lives on small mammals such as rodents. Many birds carry ectoparasites, external hitchhikers that can be more or less benign. These include microscopic feather mites or flat hippoboscid flies that bite, but the most visible and damaging ectoparasites on birds are ticks.

Climate change may well be responsible for an increase in ticks with mild winters failing to knock back ticks that usually lie dormant all winter in the soil and most often succumb to cold weather and freezing conditions.

There's little doubt that a tick can be detrimental to its bird host. Nearly all ticks we've seen on birds have been attached near eyes, ear canals, crowns, or foreheads - the places where birds can't easily use their bills and have trouble scratching with claws, so it's easy for the parasite to hang on while taking a blood meal.

We have seen ticks on several species of birds and having removed them, have subsequently retrapped the birds and found no new ticks and healthy birds which is evidence enough to continue removing any ticks from birds we catch.

Fall is the end of the banding season and it's always a bit sad when nets are taken down and banding gear put away and we all have to wait out the long, cold, dark winter months for spring and the arrival of the first Neotropical migrants but October is also our favourite month as our very favourite birds arrive - Northern Saw-whet Owls!

The Saw-whet Owl is one of the smallest owls in North America and is only 7-8 inches from bill to tail although its wingspan of 18-22 inches makes it appear larger in flight. Its small size allows banders to capture them with the same mist net techniques used for passerines.

They are nocturnal owls, hunting mainly at dusk and dawn and roosting in dense conifers during the day relying on the foliage cover and their plumage for camouflage. Following last years successful monitoring we were all impatient to see if 2015 would produce any of these amazing little birds!

Northern Saw-whet Owls begin migrating as deciduous foliage nears peak colour, utilizing habitats along their migration routes that are similar to their breeding habitats, and ends approximately 1 month after leaf fall, thus migration begins during mid-September north of 45 degrees north latitude.

Monitoring is conducted from dusk until dawn (if you can stay awake that long!) using an array of nets with an audio lure placed at the junction of the central nets with net checks conducted each hour during the night. This means many hours of sitting around in the cold and dark trying to keep warm and telling jokes and mindless stories to stave of the boredom! As we've said before you actually find a lot out about people when you're owling with them!

But as the following photographs show it's all worth it when net rounds produce owls. The anticipation is palpable as we walk out to our owl nets which are the furthest from the banding pagoda and everyone's steps get quicker the closer we get until we are all running the last few yards to get there first....Sarah Gray!!!

And one evening we caught eight of which these two seemed totally captivated with each other and completely oblivious to anything else including us!
Of course everyone loves them and how could you not? Of all the species we catch there really is something quite special about them. Maybe it's because they are nocturnal living their lives in the darkness, maybe it's because people just have to have their photo taken with them....even when they are wearing silly hats!
Each bird is placed in to a soft straitjacket (below) while they are being processed - this ensures careful handling and allows us to carefully check heavily feathered legs; to be certain that the right band size is used and to feel both legs to verify that the owl is not already banded. Following processing each owl is then weighed to determine body mass which, together with wing chord, is used to help separate males from females - females being larger than males.

An adaptation for silent hunting at night are the comb like serrations on the leading edge of the primaries which distribute air rushing over the wing into small vortices, thereby reducing turbulence and noise (photo below).

Unlike passerines the structure of the toes is different in owls as the outer front toe (digit 4) on each foot can be swiveled to face the rear (a configuration termed Zygodactyl). When in flight, 3 toes (digits 2, 3 and 4) face forward, and one (digit 1) backwards but when perched, or clutching prey, the outer toe (digit 4) swivels to face the rear.

The combination of this toe configuration, needle sharp claws and nobbly protuberances on the underside of the feet all help owls to grip prey (photo below left)

Hearing, of course, ranks high in its importance to birds and their survival. The ear openings of most birds are hidden under feathers and only visible on a bird in the hand.

Owls' hearing is particularly acute because many hunt by sound alone. They have, therefore, many unique adaptations.  The ears on many owls, for one, are asymmetrically arranged on the sides of the head, that is, one is usually higher on the head than the other and they are often shaped differently, this helping to locate prey and calculate its exact location.

Also, in front of the ear on both sides of all owls, is a movable skin fold that no other group of birds has. Its purpose, to reflect and concentrate sound waves coming from behind (photo below right).

Ageing and sexing Northern Saw-whet Owls is relatively easy. Hatch year (HY) birds do not replace remiges (primaries and secondaries) in their preformative molt and therefore, all primaries and secondaries are a uniform shade of brown.

This is even easier to see under Ultraviolet light, as the porphyrin in the feathers glows pink across the entire underside of the wing.

A second year (SY) bird replaces the outer primaries and inner secondaries after its first breeding season. These replaced feathers contrast visibly with the retained inner primaries and outer secondaries and again, the new feathers glow pink while the older feathers are washed out and bluish under ultraviolet light.

After second year (ASY) birds show a pattern of mixed new, one-year old and two-year old feathers. 

Third year (TY) birds like the bird below show an increasingly fragmented pattern with 3 distinct generations of feathers and after third year (ATY) and fourth year (4Y) birds show complex patterns in which 4 generations of feathers can possibly be identified.

But apart from all of the science they really are the cutest birds and no one who holds one can fail to fall hopelessly in love with them!

Hummingbird monitoring continues well in to fall as although our migrant hummers have long since left, our resident Anna's Hummingbirds like this stunning adult male stay to tough out Vancouver winters. Although weighing little more than 4 grams these tiny birds somehow manage to survive our long, dark, cold and extremely wet winters here in Vancouver.

They do this by eating nectar from flowering plants and feeders and by eating small insects, like midges, whiteflies, and leaf hoppers and will also readily take to tree sap (and insects caught in it) leaking out from holes made by sapsuckers.

Another adaptation to surviving winter nights is the ability to enter torpor. Anna's Hummingbirds normally have body temperatures around 41 degrees Celsius (107 degrees Fahrenheit) but when temperatures fall, their breathing and heart rate slows, and their body temperature can fall as low as 8 degrees Celsius (48 degrees Fahrenheit). When the temperature warms, they become active again in just a few minutes!

So that's it for another banding and monitoring season at VARC. 2015 has been an exciting year where we were able to conduct a record number of banding hours and process a record number of birds! In addition to hosting the WBBA conference we received record numbers of visitors to the station which included an increased number of children who were able to learn about environmental issues as they relate to the protection and conservation of our songbirds – busy year!

And finally. as always none of the work we do would be possible without the help of so many people which now seemingly includes a cast of thousands between all of the Friends of VARC, 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 - again thank you all!

See you all in spring 2016 - Happy winter banding, ringing and birding wherever you are in the world! 

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