Summer (June/July) 2017
Setting 3.45 am alarms to get to the banding station pre-dawn is
tough during the summer months especially when it's the weekend and
everyone else is having a lie-in but it's totally worth it when the
mist rises over the old-field habitat where we band and nets are
opened for another banding session!
of the month had to be this unique and quite spectacular after hatch
year male hybrid Anna's / Rufous Hummingbird!
Hummingbirds and ducks are the families of birds that are known to
hybridize a lot of course but usually within the same genera such as
Anna's and Costa's Hummingbirds in California for example. But a
hybrid cross genera like this Anna's (Calypte) and Rufous
(Selasphorus) is much rarer.
The following photographs show the
phenotypic traits that were suggestive of each parent.
two head shots above of the hybrid show phenotypic traits of both
species as can be seen by comparing both adult male Anna's and
Rufous Hummingbirds below.
The combination of these traits was
a perfect blend of the two species with green on the back (like
Anna’s) with some rufous on the sides (like Rufous) and gray below
(like Anna’s) and iridescent pinkish-red feathers covering the
throat, chin and forehead (somewhere between Rufous and Anna’s!)
Adult male Anna’s (below left) has
green on the back and flanks and gray below with no rufous on the
body and iridescent magenta-pink feathers covering the entire head
Adult male Rufous (below right) has
rufous face, sides and nape and a mostly rufous back and an
iridescent red throat and chin not extending on to the head.
rectrices of the hybrid also showed phenotypic traits of both
species, the central rectrices similar in shape and colour to an
adult FEMALE Rufous and the outer rectrices similar in shape to
female Rufous but in colour to male Rufous!
Anna’s rectrices are broad, green and with black (adult males) or
white tips (females and immature males).
Rufous rectrices are primarily rufous
with black tips (adult males), the central rects narrow and pointed,
the central rectrices of females are broader and green with some
rufous at the base. (photos below)
SECOND Anna's / Rufous Hummingbird hybrid was captured at the end of
July, this time a hatch year (HY) male showing the same phenotypic
traits of both species and almost certainly an offspring of the
adult male above!
perhaps likely that hybrids in suburban-residential areas will
become more common as these massively disturbed habitats allow for
species that are not normally found in the same localities like
Anna's (resident) and Costa's (summer visitor) in California which
is similar to Anna’s and Rufous here but our two are in different
genera which makes this all the more exciting and it will be
interesting to see if these birds overwinter here like Anna's or
attempt to migrate like Rufous!
to BICs Debbie Wheeler and Kerry Kenwood for taking charge of the
June Bird Monitoring and Banding Workshop when another full house
spent a long weekend learning about molt and ageing of North
American landbirds in the hand.
|We also welcomed
Dutch Ringers Klaas and Annemieke van den Berg to the station. Klaas
and Annemieke were on a month's trip to western Canada and had to
include a visit to Colony Farm! Klaas got to see a whole bunch of
target species and Annemieke got her wish to see Hummingbirds in the
hand. In return we asked them to send us a Bluethroat when they got
It's was great to meet
you guys and hope to see you again in the future!
And also Polish ornithologists Leszek
and Małgorzata Bujoczek who for some reason missed the photo op! But
it was great to see you guys too and safe travels on to the Rockies
and on your way home!
The North Vancouver Ecology Centre
NatureKids came by for their annual visit to the banding station.
We've talked previously about the importance of our outreach and
education programs to raise awareness of environmental issues as
they relate to birds and this
from this little girls parents sums up how impactful these sessions
can be for children.
and July is the nesting season for many songbirds when a lot of
energy is invested in to young, building nests, incubating,
attending dependant nestlings and for some species repeating this
exercise up to 3 times a season!
It's not surprising that some
songbirds like crows get territorial and defend their young when
this much energy has been expended in to raising them!
We found two Black-headed Grosbeak
nests close to the banding station. Black-headed Grosbeaks build
very loosely constructed nests often making it easy to see eggs
through the bottom maybe to provide ventilation to keep eggs
and nestlings cool. They are typically placed in the outer branches
of a small deciduous tree or bush and often not well concealed
leaving them vulnerable to predation. Such was the situation with
the two nests we found, one of which failed completely after eggs
were taken and the other which managed to successfully fledge just
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
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 Song Sparrow
with a 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.
result of all of this breeding activity is, of course, baby birds
which undertake the prejuvenal molt in the nest prior to fledging
and which produces the bird’s first set of non-downy feathers called
Many of these very recently fledged young birds are incapable of
sustained flight because their wings and tails are not fully grown,
and are dependant upon parents for food. As we have said before, we
always flag these birds by attaching red pegs to the bird bags they
are in which alerts the banders to give them first priority for
rapid processing at the banding station and then to take them back
as soon as possible to a location near where they were captured.
Baby birds like this hatch year
Swainson's Thrush show all of the characteristics of juvenal
The first is dull, streaked or spotted 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. The buffy teardrops along the rachis of the lesser and median
coverts shown here are diagnostic of juvenal feathers of members of
thrush family and are often present on retained juvenal greater
coverts following the preformative molt after the breeding season.
These "baby" birds also have soft,
fleshy, pinkish or yellowish gapes as shown here although some
species, particularly some finches and thrushes can retain fleshy
gapes even as adults.
Other characteristics of birds in full juvenal
plumage include very loosely textured feathers, particularly the
undertail coverts as shown below of the hatch year Swainson's Thrush
Around the base of shaft they are more downy and toward the tip show
a reduced area in which the barbs are linked by hamulus-barbicel
hooks to form an interlocking vane, the barbs spaced more widely
apart along the shaft giving the juvenal vane a coarser look.
The feathers of the underwing (photo below left) and
tibiotarsus (photo below right) develop later and are often devoid
of feathers as shown below in the photos of the same bird.
Yet another characteristic of birds in
juvenal plumage is very dull, brownish eye colour as shown in this
hatch year Spotted Towhee.
Some more baby photos from top left
clockwise, Song Sparrow, Common Yellowthroat, House Finch and Spotted
Towhee. Most hatch year birds in
full juvenal plumage cannot be reliably sexed but some like the
Spotted Towhee can as males like this one have blackish rather than
brownish flight feathers.
Juvenile European Starlings can be sexed based on the
colour of the iris which is dark brown in males and pale grayish
with a yellowish tinge in females.
Although there are an estimated 200
million or more European Starlings in North America they are
uncommon birds for us at Colony Farm normally only seen in over
flight above the old fields where we band so the occasional one that
turns up in a net is always blog worthy like this one!
continued with our Tree Swallow special species study involving
radio frequency identification (RFID) technology. RFID allows the
unique identification of individuals and automated recording of the
presence of tagged birds at fixed locations such as nest boxes.
The technology is being used to better understand the connections
between adult nesting behaviour, weather, food availability and
nestling growth and survival.
For details of this project please see
the photo essay in the
spring/summer 2015 blog.
All this talk of research and
science can't take away from the total cuteness of these
baby birds which we all fall in love with and it's easy to see why!
It was also an opportunity to try out our
new cuteness scale which seemed to be working pretty well! (photos
below: Tree Swallow, Cedar Waxwing and Golden-crowned Kinglet)
Next up was a
juvenal Gray-headed Cowbird - OK not a Gray-headed Cowbird but a
juvenile male Brown-headed Cowbird with an unusually gray head!
Like crows, cowbirds get a very poor rap being
blamed for songbird declines but the fault lies squarely at the door
of humans for the continuing conversion of forest to agriculture and
other land uses.
Originally birds of the open grasslands following
cattle herds in search of seeds and disturbed insects Cowbirds
evolved to become brood parasites, laying their eggs in the nests of
other birds and abandoning their young to foster parents as they
continued their nomadic lifestyles.
In the course of a single nesting season, a female
cowbird may produce as many as 40 eggs over as many or more days.
The challenge for her is she has to find as many nests of potential
host species at just the right stage of laying in order for just a
few of her offspring like this one to have the chance to survive to
independence. This is actually about the same number of young that
many cowbird host species themselves will raise in a single season
by tending just one or two nests containing four or five eggs each!
The challenge is when cowbird nesting success almost completely
eclipses the nesting success of its host species particularly in
small forest fragments surrounded by agricultural landscapes. Some
of these fragments are large enough to attract forest nesting host
species such as Thrushes and in these areas the hosts experience
exceptionally heavy cowbird parasitism pressure
due to the fact that a very large population of cowbirds is
supported by the ever expanding surrounding agricultural landscape.
This can cause what is known as a "population sink" meaning the host
species may effectively raise only cowbird young but again, the
irrefutable negative impact of cowbirds on some host species in such
areas is symptomatic of the continuing conversion of forest by human
Swallows are part of the guild of
aerial insectivores which have suffered precipitous declines in
recent years with research in Canada showing that populations of
Barn and Bank Swallows to have fallen by 70% and Cliff, Northern
Rough-winged Swallows and Purple Martin by over 50% in the past two
The old field habitat at Colony Farm is critically important to
these aerial insectivores and 7 of the 8 species of NA swallow are
found there sometimes in large numbers.
Northern Rough-winged Swallow is one of the less common swallow
species found in the Park nesting in burrows and cavities in various
substrates including pipes and other man made structures.
It gets its name from the serrations
on the leading edge of the primary feathers which are distinctly
hooked in males and smaller and straighter in females. The edge
really is rough to the touch and similar to running a finger along
the edge of a coarse file!
The photo below show the leading edge
of the outer primary at 5 times magnification (photo. credit Dev
Manky). The function of the
rough wing edge still isn't known.
end of July many birds have already started their prebasic molt like
this after hatch year (AHY) male American Robin at the very
beginning of its definitive prebasic molt which includes all body and flight
feathers normally starting with the lesser and median coverts, then
tertials and innermost primaries and corresponding primary coverts
although this bird had yet to molt its tertials.
And a nice story to end the blog when
neighbours found a baby Barred Owl on a trail at the back of our
house when they were out walking their dog on May 8th. At the time
it was just a bundle of fluff that appeared to have fallen out of a
nest cavity high up in tree. We were away in Toronto so they called
the folks at
Orphaned Wildlife (O.W.L.)
where we band all the rehabbed raptors. It was taken in and fostered
by their resident pair of Barred Owls and brought back for release.
After a few photos we released it and it flew to the eaves of the
house, sat there for a while getting its bearings and then flew off
in to the forest!
The photos show what a difference a couple of months make in the
life of a young owl!
always a massive thank you to all of VARC's
without whom none of the work we do would be possible.
It never ceases to amaze me when we turn up at the park gate at 4.45
am to see everyone gathered - definitely a few sleepy faces and
yawns but everyone happy and excited for another banding session!
What a truly great group of people! Thanks again!
are copyrighted © and are not to be used without permission