April 27th – Migration Vagaries

Huge difference in the timing of Snow Bunting migration in Labrador. -Cheryl Davis


The Labrador Snow Bunting Project (on Facebook), created by Cheryl Davis and Vernon Buckle, has been very interesting to follow. The idea for it grew out of the tedium of COVID-19 stay at home demands which left people without much to do. So….why not look for and report on the arrival of Snow Buntings on their return migration to the Arctic!? (I almost wrote Canadian Arctic but it has become clear that a good number of the birds migrating through Labrador are on their way to western Greenland.)

I was reading about different types of migration in The Cornell Lab of Ornithology Handbook of Bird Biology trying to sort out how to classify the annual movements of Snow Buntings. Heading south in the Fall I would classify them as “obligate migrants”. They “undertake predictable annual migrations to distant non-breeding grounds, sometimes traveling thousands of kilometers each season…..no individuals stay behind on the breeding grounds.” We usually think of birds in this category as the long-distance insectivores that breed in the boreal forests of Canada and Alaska and then fly to Central and South America for the Winter. Quite often these birds will return to the same wintering locations year after year, many to the same spot/territory. The timing of their northern migration is pretty consistent from year to year, seemingly controlled by photoperiod or day length. The arrival of warblers in southern Ontario “hotspots” is quite predictable within a few days. Their migration timing doesn’t seem to have much to do with local conditions of weather or food availability. {Although cold and adverse winds can slow their progress down for a few days.)

Snow Buntings differ a great deal in how they spend their Winters and when they time their return migration. Banding results by members of the Canadian Snow Bunting Network have shown that Snow Buntings may return to a particular wintering area from one year to the next provided there is snow cover and cold temperatures. In one unusually warm Winter a bird banded in southern Ontario (by David Lamble just outside of Fergus) the year before only came as far as Rimouski on the south shore of the St. Lawrence River (1200 km to the NE) – there wasn’t enough snow or cold to warrant his (it was a male) going any farther. Even when they do return to an “area” they are pretty nomadic ranging over a wide territory. Sure, we have recaptured birds we have banded in other years but some of our birds have been recaptured well to the north or east and vice versa. Unlike many warblers for example they don’t return to a spot but rather to a large area and within that area are nomadic in their search for food.

And the timing of their return doesn’t seem to have nearly as much to do with photoperiod as with weather conditions. For all intents and purposes our “winter” this year ended around the end of February – in fact, we had only about 3 weeks of cold with snow. And then it began to warm up and the buntings disappeared. Where did they go? You can see from the above map/diagram they began to head back north. They are about a month ahead of last year. Most of these would be male birds getting the jump on claiming a territory for when the females arrive – which might be a couple of weeks later. Hmm…does this make them “obligate nomads”?

Early morning moonset by the pond. -DOL


I have been waiting (I would like to say patiently….but maybe not) for the regular Spring birds to return. It seems to be a very slow April. But today things began to pick up. I had my first sighting of Common Loons – 5 of them heading NNW about 25 minutes after sunrise (their having spent the night on Lake Erie’s Inner Bay and then moving with the sun). That was a good sign. And then I caught and banded my first White-throated Sparrow of the season – another good sign (they’re a little late). I was joined today by Joanne Fleet and she worked her peculiar magic by turning up the first warbler of the season: a Yellow Warbler. In total we banded 20 birds:
2 Mourning Doves
1 Downy Woodpecker
3 Tree Swallows
2 Ruby-crowned Kinglets (still seeing just males)
3 Swamp Sparrows
2 White-throated Sparrows
5 Red-winged Blackbirds
2 American Goldfinches

ET’s: 39 spp.
Rick

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