This thing just gets better and better (and certainly more intriguing) all the time! For me, the critical questions surround when and where the buntings make the “big jump” to Greenland. Intuitively, I surmised that they would move north along the Labrador coast to Cape Chidley and then either jump from there or work their way across Baffin Island and then head over to Greenland. But Darroch’s findings, that some birds are putting on enormous fat reserves, has put a spanner in that surmise. Darroch found that the birds he was catching on the weekend were carrying big fat loads and were weighing between 45 and 55 g. One bird weighed in at 61.8 g!! David Hussell, who has studied Snow Buntings (and Northern Wheatears) extensivly in the High Arctic, had this comment:
61.8 g must be a record for a SNBU.
The BNA account mentions rapid body mass increases in spring, including ”In Quebec during Mar and Apr, body mass of captive birds rapidly increased from <40 to>50 g (Vincent and Bédard 1976)”. The reference is: Vincent, J., and J. Bédard. 1976. Fat reserves in Snow Buntings. Can J. Zool. 54: 1051-1063.
The distance from the northern tip of Newfoundland to Cape Farewell is about 1120 km. Presumably SNBU, especially early-arriving males, would need to arrive with some fat reserves.
If you’re interested in reading this article, here it is:
VINCENT AND BEDARD 1976 Captive SNBU Fat CJZ
Further, Darroch noted that some birds were putting on weight rapidly with one bird going from 49.6 g to 55.4 g in just 48 hours!
So, I’ve started to change my thinking. Now I’m beginning to wonder if some might make the jump right from Newfoundland.
Go over some of the email interchanges I’ve had over the last couple of days and see what you think>.
First, Tina Leonard sent a map outlining some of the possible bait and capture sites on Newfoundland and this commentary:
Still waiting for arrivals here in Pasadena, but have friends baiting in a few other areas where SNBU show up every year. I’ve attached a Google Earth image for your interest – friends are baiting in Pollard’s Point (SNBU have been here for 2 weeks now – I plan on heading there this Friday to band) and in Woody Point, just 3 km SW of Darroch (no birds seen there yet). Also have friends on the watch who live in St. Anthony on the northern tip of the island (always reports of birds here) and on Change Islands off the NE coast (also lots of birds reported here). No birds arrived in St. Anthony so far and I haven’t heard from Change Islands folks yet.
Hopefully this long weekend is a fruitful one! It’ll be hard to match Yann et al’s 400 though!
When I put out my interest in finding the distances from some of these spots to the west coast of Greenland, Peter Thoem took up the challenge and came up with these 3 maps:
When I started playing around with these maps I noticed that if a Snow Bunting flew from St. Anthony along the Labrador coast to Cape Chidley and then directly to Greenland, the distance would be approximately 1,900 km. But the distance directly from St. Anthony to Greenland would only be 1,150 km. – a difference of about 750 km. Flying at a resonable 30 km/hr this would take only 38 hours (without wind assistance). This is very possible given that birds as small as Blackpoll Warblers will fly over 80 hours continuously in their southern migration over the Atlantic to South America. So, a good ‘strategy’ could well be to pack on a LOT of fuel/fat and make one long flight directly to the breeding ground. This would agree with findings that Christie Macdonald made with Snow Buntings fitted with data loggers on Southampton Island.
Here are some of her comments:
This is really interesting having a bander along migration routes now.
Of all the birds we have banded in the arctic or on wintering grounds,
the fattest I can remember weighed ~45g. Crazy to think that is the low
end of your range! Hopefully a bit of snow will keep the birds coming to
your traps for a while longer. Our geolocators show that individuals
will spend up to a month at a spring staging/stopover site, but then
make relatively quick trips to their final breeding site. This quick
fattening, combined with relatively short migration season through your
area suggests maybe the “east coasters” are doing something different. I
wish we had a breeding population in Greenland we could track too!
Anyways, really interesting to hear your reports, incredible the
insights that this additional geographic effort has provided already!
As you can see from Alex Anctil’s remarks from Rimouski below, it would appear that this pronounced fattening doesn’t happen until the birds are well along on their route:
We haven’t caught any SNBU recently. The average weights for all males
this winter was 39.88g.
ASY males tended to be heavier with an average of 40.12g while SY
males averaged 39.66g.
All females we caught (9) were SY and averaged 34.67g (including a
female with a fat score of 5 that weighed 40g).
I don’t think there as been a temporal trend in the weight of Buntings
near Rimouski during the period we caught them, but there as certainly
been variability. Indeed, some days they all seemed to be heavy and
some days they all seemed to be light.
Good job on catching all these buntings Yann! Are you catching them
only with the ground traps? I hope you’ll get one from Rimouski!
As the migration proceeds, there appears to be a change in the age-sex composition of the flocks. Darroch:
We are starting to see / band some females and SY males this week. This is
all a learning experience about dynamics of SNBU migration through
Newfoundland for me so I am really curious to see what patterns develop
through the course of the season. One challenge though may be that we’re
losing our snow cover quickly and there seems to be a parallel decline in
interest in the bird seed as natural food is easier to find, so trapping
may get harder later in the spring. We did get ~10 cm of snow last night
though so I’m going to head out later today and see if that has made them
easier to trap.
I had the same questions about how far they plan to go with this much fuel
in their tanks and which routes they take northwards. I know my friends who
live along the Labrador coast see big migrating flocks in spring (e.g. in
Nain), so at least some stop along the way. I’ll send them a request to try
and get some pictures / info this spring to see about timing and sex
composition of these flocks. I’m also curious to see how our weight data
compare to that from banders along the north shore in Quebec. Also hoping
for some more retraps to get a better sense of how quickly they’re bulking
up (maybe biased data though given the amount of corn and millet I’ve been
shovelling their way!).
PS when I banded that 61.8 g bird I actually re-zeroed the scale and
weighed him a second time because I couldn’t believe the first reading!
There are likely a number of ‘strategies’ – some individuals may make the jump from Newfoundland while others
take a more coastal route initially. These latter birds should start to show up further north in Labrador soon.
FYI I sent a request for updates on buntings to some of the people I work
with in Labrador and George River. Most are Inuit who spend a good deal of
time on the land so should be good wildlife observers. One has written back
to say that a handful have already arrived in Nain but nothing like the
numbers he expects to see soon. These must be tough birds because Nain is
pretty far north, though it fits with the info I’ve seen indicating that
the old males begin to arrive in Greenland around now too.
Banded 10 more last night, a 5/5 split between SY/ASY males so there does
seem to be a bit of a shift towards younger birds here. I didn’t get any
females but scanning through the flock I could only see 3/30 so about 10%
Christie did some digging:
Awesome! I just checked the weather office, and apparently the snow
depth is 81cm today. Not sure if that means there is much/any open
ground yet, but it sounds like a lot!
And then noted:
A few buntings were observed around Ottawa earlier this week, so there’s
quite a spread right now.
Quite a spread indeed! From Ottawa to (almost) Nain. And all of them winging their way toward the breeding grounds. Awesome!