Vancouver Avian Research Centre

.....Research - Conservation - Education

Summer - 2014

Breeding season is in full swing during June and July when we cut back banding to 3 days a week so as not to unduly disturb breeding birds.

Breeding birds develop breeding characteristics which help us to separate males from females in sexually monomorphic species which otherwise look exactly alike.

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 identical 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 and is illustrated in the photo below left of a male Spotted Towhee with fully developed 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 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. vascularized and swollen) such as in the photo below right of a female Black-capped Chickadee with a fully developed BP.

The result of all of this breeding activity is of course baby birds!

Many of the birds banded during the summer months are very recently fledged young such as the Black-throated Gray Warbler below in full juvenal plumage. As we have said before, when we catch birds like these in our nets (i.e., very young birds incapable of sustained flight because their wings and tails are not fully grown in), we always give them first priority for rapid processing at the banding station, and we take them back as soon as possible to a location near where they were captured.

Note the very loosely textured feathers and the wispy traces of natal down still clinging to this locally hatched bird, one of the characteristics of juvenal plumage.

Shortly after capturing this baby, we caught what was almost certainly the mother, a female Black-throated Gray Warbler with a receding brood patch. Despite plumage which was now close to 12 months old and having gone through a Neotropical migration and a breeding season in and out of the brush feeding hungry nestlings, the wing of this after second year (ASY) female was showing remarkably little wear.  
Birds in juvenal plumage look very different from their adult counterparts and can easily be misidentified. This hatching year Lazuli Bunting is a good example with only a very feint bluish wash to otherwise very dull, brownish plumage.

Dull, streaked or spotted plumage is another characteristic of birds in juvenal plumage. Recently fledged birds normally spend the first part of their lives either on or near the ground where they are vulnerable to predation. Dull, streaked or spotted plumage acts as camouflage to help protect them during this time.

These "baby" birds also have soft, fleshy, pinkish or yellowish gapes  sometimes making them look grumpy as in the photo of the baby Bewick's Wren (below bottom right).

The "baby" birds shown clockwise from top left are a particularly cute Cedar Waxwing, Swainson's Thrush, Bewick's Wren and White-crowned Sparrow.

Again, very young birds with this sort of appearance are still entirely dependent on parental care (for 2-3 weeks longer), and we make every effort to quickly reunite them with their parents and brood mates.  

Other characteristics of birds in full juvenal plumage include very loosely textured undertail coverts (photo top left) and the tibiotarsus (photo top right) and underwing (photo bottom left) develop later and are often devoid of feathers. hatch Year birds dependent upon their parents for food also often show fault bars (photo bottom right) distributed as straight lines across tail feathers and discussed in previous blogs.
As well as being a demanding time for adult and baby birds summer is also a demanding time for banders having to set alarm clocks for 3 am to get to the banding station for dawn!

Kelly comes all the way up from Washington State to volunteer with us at Colony Farm and has some interesting stories of conversations with border guards when she is coming in to Canada at 3.30 am and tells them that her purpose for visiting Canada is to band birds!

Here she is taking a well earned nap between net rounds!

We were also approached by an organization called A Rocha who wanted to start a swallow monitoring program on their 40 acre property in south Surrey. A Rocha is an international organization which engages in scientific research, environmental education, community-based conservation and sustainable agriculture projects.

The first part of this project involved banding a Cliff Swallow colony under the eaves of a heritage barn on the property - the challenge was the barn was over 50 feet high!

My credibility at catching birds was already shaky given my attempts to catch Belted Kingfishers  at a fish hatchery where we only caught a single Song Sparrow and further damaged last fall when our Northern Saw-whet Owl monitoring didn't produce a single owl!

Still, not to be deterred I designed a 6m pulley net to hoist up in front of the nests, the only problem was who was going to volunteer to climb a rickety ladder 50 feet off the ground to attach the wooden extensions and eyelets necessary to operate the net. Enter Ivand (yellow T-shirt below) our all round good guy volunteer who not only shot up the ladder with various tools and rope in his hands but did it in his wellies!

Redemption for me and my bird catching skills when we almost immediately caught our first Cliff Swallow and proceeding to catch 20 more!

Cliff Swallows are part of the guild of aerial insectivores, birds that specialize in feeding on flying insects and populations have fallen steadily and consistently since 1970.

Having complete first and adult prebasic molts makes ageing adult birds impossible and sexing is difficult too given very little difference in biometric measurements such as wing chord and that males can also develop partial brood patches. Separating juveniles from adults is easy as the photos below show; adults have buffy and well defined forehead patches and chestnut throats and cheeks whereas juveniles have brownish and less well defined forehead patches and mottled, blackish washed cheeks and throats.

Thanks to A Rocha for their interest in this project (and for providing lunch!) and we hope that ongoing monitoring efforts in the coming years will contribute to continent-wide research programs underway to better understand the breeding biology of these amazing birds.

And speaking of swallows we all fell in love with a pair of Barn Swallows which took up residence in the banding pagoda! Despite all of the activity and countless visitors to the station, the birds proceeded to build a nest two feet above our heads and raise a brood of 5 nestlings!

Unfortunately, the story didn't have a happy ending as we arrived one morning to find the nest had had been predated. The female spent the entire morning returning to the pagoda with food for her nestlings and sat on the window sill calling for them. It was really touching and watching her it was tough not to think that birds have feelings!
Between two VARC Family Days, a Young Naturalists and 'Sparks' Girl Guides visits it was a busy time for us with young visitors. Our Family Days have become a huge hit and we love having kids at the station where we can talk to them about environmental issues as they relate to birds.
Our outreach and education programs focus on teaching kids through hands on interaction with birds about the importance of habitat conservation and what they can to make a difference. It's not difficult to see from these photos that this unique experience has a real impact on kids and we hope further triggers a lifelong interest in birds and the environment.

Special thanks to Martine Cutbill who organizes VARC Family Days with amazing arts and crafts activities for kids making bird puppets and face painting. After talking to kids about cats and the impact they have on birds in North America the little girl below right said "she was an indoor kitty!"
These events are not just fun for kids - we have just as much fun hosting them and visiting birder and bander Pierre Geoffray couldn't resist making an arts and crafts owl out of a toilet roll!

We met Pierre on a birding trip to Ecuador and it was great to see him and he has promised to come back again for fall migration banding.

And British A Ringer and Trainer Tim Ball came back for a visit. It's always great to see Tim and we always manage a "ringing tick" for him, this time a Red-eyed Vireo!

He still owes me a Red Kite which he has promised on my next trip to England!

Red-eyed Vireos are not common birds for us, preferring deciduous tree tops to the low brush and old field habitat where we band so the occasional one that turns up in our nets is a very welcome surprise.

We aged this bird as an after second year (ASY) based on eye colour and lack of any discernible molt limits in the wing and no contrast in wear between the secondaries and tertials. There does appear to be a slight contrast between the greater alula covert and lower main alula feathers which are lacking the same greenish edging and although the outer primary coverts have fairly distinct greenish edging they are very narrow and tapered. Everything else however, including broad, truncate rectrices pointed to ASY but we would be interested to hear from any other banders with experience ageing REVI.

Another tricky species to age is Willow Flycatcher (WIFL) although we do get lots of practice having banded close to a thousand of them in the past several years. Molt is complex in many of the Empid flycatchers and much is not known on molting patterns in this particular species.

Unlike other songbirds where most of the molt occurs in the prebasic molt following the breeding season, in WIFL most of the molt takes place in the prealternate molt in the late winter so birds like this with an eccentric pattern of retained primaries and secondaries could be first year birds or adults. However, in looking closely at feather quality, shape and wear  between the retained and replaced remiges we determined this bird to be an adult after second year (ASY) bird.

There was no doubt as to the age and sex of this second year (SY) female Purple Finch which had replaced lesser and median coverts (red arrow) but only some inner greater coverts. Notice the glossy replaced inner greater coverts (red arrow) but skipped (retained juvenal) GC 8 (green arrow).

As Purple Finches have delayed plumage maturation, at this time of the year, brownish birds like this one could be either second year (SY) males or females; this bird however was a female with a fully developed brood patch.

House Wrens are uncommon birds on the coast so this hatch year House Wren was a nice surprise for us and completed a hat trick of wrens for the morning with Pacific Wren and Bewick's Wren also caught for banding.

Another surprise was this Pacific tree frog which turned up in a net one morning! Although they are quite common and we often hear them calling they are surprisingly difficult to see. It's not often we catch non-avian visitors so we thought it was blog worthy or should I say frog worthy!
And speaking of blog worthy the work that the Orphaned Wildlife Rehabilitation Society (O.W.L) do to rehabilitate and release injured and orphaned birds deserves special mention. The facility specializes in raptors where more than four hundred birds are bought in each year almost all of which would certainly suffer a slow and painful death without the special care afforded by the dedicated staff and volunteers at O.W.L.

We periodically visit O.W.L. to band and weigh rehabbed birds ready for release in the hope that reported bands will help determine future survival rates.

Of course, raptors come in all shapes and sizes and switching between size 9 rivet bands for eagles to size 3 bands for small owls is always interesting.

I fell in love with a family of juvenal Great Horned Owls and we all fell in love with a Northern Pygmy Owl which seemed ridiculously out of place among all the massive raptors we banded this day!

Hummingbird monitoring continued with record numbers of both Rufous and Anna's Hummingbirds banded so far this year. The technique we use for banding hummingbirds involves placing them in to soft 'strait-jackets' which allows the safe handling, banding and measuring of these tiny birds. Hummingbirds are always firm favourites with visitors to the station who, like us, can't fail to marvel at these tiny dynamos with wings beating up to 80 times a second and hearts beating up to 1,200 a minute in flight!

We regularly receive reports of banded birds from the public and digital photography is enabling people to capture band images that we can often decipher to locate the bird in our database like this HY male Anna's Hummingbird visiting a feeder in Port Coquitlam just a few kilometers from the banding station.
Finally, we have been working for the last 12 months or more on a new web portal to provide identification and comprehensive molt and ageing information of birds in the hand using high resolution photographs with precise information and detailed instruction on ageing using molt and plumage criteria. Initially, the database will contain the 90 plus species banded at VARC but we hope that the database will be expanded to become a repository for many of the birds of the world as ornithologists and photographers contribute to the site. The portal will be launched in the fall under World Bird Research - more to follow!

Thanks to Mark Habdas, Kerry Kenwood, Carol Matthews, Jason Jones, Debbie Wheeler, Kyle Norris, Louise Routledge, Monica Nugent, Sara Legros, Rufus Macintyre, Cyril Chan, Ivand Pulido, Andrew Venning, Kelly Palmer-McCarty, Martine Cutbill, Danielle Zandbergen, Christian Lunn,  Eleanor Duifhuis, Kate Gibson, Cadi Schiffer, Jagdeep Sekhon and Leslie Bol for their help with summer banding - as always VARC would not exist without the energy, enthusiasm and commitment of all of our amazing staff and volunteers!

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