Hi Tweets,

Gonna try again on this 'Robins' post; sent it last night but didn't get out
to the world for some reason.

M

Hi Tweets,

L Smith says:
>4 Robins showed up today. First good sign of Spring.

Interesting. Don Cecile, over on Vancouver Island and I have been chewing on
this one for a few days, whether the appearance of robins is the same thing
as the arrival of robins, completely begging the question of whether either
is spring. Last I looked, not.

(Various snips here and there)

On Feb 10:

DC:
More locally, I have noticed migrant Robins. Every year I try to pinpoint
their arrival and all I know so far is that it's within the last week of
January and the first week of February. Difficult to pinpoint since there
are always some around through the winter but when you see a pasture covered
with them (mostly males in bright plumage) it becomes pretty clear that the
move is on.

MP:
Veeerrry interesting! Can you see any plumage details to establish race? You
may have a northerly race wintering in your area (always the basis of
'winter' AMRO in southern Ontario--fortunately, there were plumage diffs to
separate the wintering birds 'nigrideus' from the incoming local breeders
'migratorius'), or these may be wintering locally in a close but
undiscovered location. You may have an eqivalent situation with 'T.m.
propinquus', the Charlottes race. Godfrey doesn't say if that's a sedentary
race, but if the Charlottes give us 'Sooty' Fox Sparrows, there's no reason
we can't get their robins as well. Back east, AMRO return mid-week 2 March
in southern Ontario, and our big (000's) AMRO (prob. race 'migratorius')
migration here in Van BC hits late March-early April. Big concentrations in
these months (Jan-Feb) are usually big flocks that have wintered locally,
living on
berries in the freezes, and roaming around waiting for the pastures to dry
out enough to bring worms up.

DC:
I would have to do some reading to find out about what to look for in terms
of subspecific identification. Every year at this same time, I have watched
Robin behaviour and noticed a few showing up here and there that exhibit
potential migratory behaviour then upon closer examination, I find pastures
that are just full of bright looking males. This pasture is watched fairly
frequently and is closely inspected during CBC, in fact I don't think we had
this many robins on the entire count. I will have to inspect another robin
hotspot that I know.
This is also what I had always found interesting, that because the eastern
migration began in March, as you have stated, why should I think it occurred
so early here. But then I remember that the swallow and hummingbird
migration here is months ahead of back east. Furthermore, to complicate
things, so many robins overwinter in Victoria and the lower mainland that I
would think it nearly impossible to detect the first migrants. In an area
such as here, where there appear to be significantly lower numbers of
wintering robins, where do all these birds come from? And, btw, I did not
detect any robin incursion on the west coast, but then that area is just an
anomaly anyway when it comes to migration.


On Feb 15.

DC:
re: AMRO
(mostly males in bright plumage) it becomes pretty clear that the
move is on.

MP:
...I don't know if this is a case where
plumage implies migration (as we usually assume in songbirds) or is just
done on the critter's own timetable and doesn't signify anything except this
year's Spring Collection.

DC:
Perhaps a rather subjective comment on my part, but the early migrants do
ppear clean and bright and are generally mostly made up of males. The
rightness of the bill and the apparent sharper contrasts in black, gray and
ust seem to be at play, although none of these characters are considered
separate from other migrant behaviours such as the location, and what the
birds are doing. For example, I notice birds at this time of year to be
moving into people's yards, and in neighbourhoods where they were not
present throughout the winter, flights of small groups of robins above the
treetops...etc. It is clearly a subjective phenomena when trying to
pinpoint the first signs of migration (of locally common birds) that is as
slippery as the slime on a fish.
And guess what? The large flock of robins is gone.... I checked out the
location today and a few others where I would have expected good numbers of
robins and not one was found! What do you think this means? I was really
hoping to study their plumage in more detail since I have read what Bent had
to say (re: caurinus vs. propinquus)but I couldn't find a darn robin.

MP:
Word's out ;-)

Seriously, I'd have two questions. Where are the females? in an entirely
migrant area like southern Ontario, they arrive about a week to ten days
after the first incoming territorial males. Second, do these birds'
movements show any correlation with the disappearance of snow off the local
mountains? Maybe you've got a lot of vertical migrants there. I'd suggest
getting some color-bands on them if you can.


DC:
How about this one? If there are two distinct subspecies in the area would
we not expect them to migrate at different times, since they will be
latitudinally displaced for their breeding season?

MP:
Yes.

DC:
I have no practice
discerning the two subspecies but it would surely be worth looking into, and
what sort of population size are we talking about (which would make
detection easier), in terms of both the propinquus local wintering size and
their overall migratory population relative to that of caurinus.

Okay, Tweets, there ya go. Have at it.

M



Michael Price
Vancouver BC Canada When I found out that seven of my years
(604) 668-5073 vx was only one of theirs,
(604) 668-5028 fx I started biting absolutely everything.
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michael.price at istar.ca -Max Carlson (Ron Carlson's dog)