Conventional wisdom would say down the St. Lawrence Seaway, but I've always wondered what the odds are of soo many pelagic birds following the river down. James Bay is directly connected to the ocean, and not really that far away "as the pelagic flies" from Ottawa... Especially this time of year, when any birds that end up in James bay are trapped and looking for a way out.
The sibley range map will tell you to not expect a bird like a Gannet anywhere near James Bay, but with records in Alaska (+ James Bay) + the recent ADULT Gannet on Lake Superior, all point to these birds covering big ground - and I think James Bay is a very viable option for the arrival of these birds in southern Ontario.
Anyways, lets look at the weather maps and see if we can't figure something out:
Oct 20th: Large low pressure system centered over southern Ontario. Note how all the air from a huge area is flowing into it. This is the map from thursday morning, right after the wicked NE winds on Lake Ontario switched to a strong SSW as the trough (pink line) passed over us from the south.
The winds are NE in the St. Lawrence, and N at southern James Bay (doesn't really help us, now does it?) next map:
Friday:
The storm weakens a bit as the low pressure becomes elongated, and eventually two centres of low pressure are recorded (over lake Huron and another over southern Quebec).
Note in this map that the winds in Ottawa are already SOUTH, as the trough/front moves to the north. The winds are still NE in the St. Lawrence seaway however, but that big pink line is going to act as a wind block to any lost vagrants.
Winds are stronger from the NNE on southern James Bay. Next!
Late friday:
The storm is really not looking pretty right now, (actually a bit of a mess) but one fun thing happens. The two lows move northwards (almost off the map) and a third small area of low pressure forms DIRECTLY over Ottawa.
Winds are blowing steady from the S or SSW up most of the St. Lawrence Seaway. Working 100% against any birds moving towards Ontairo.
Winds in southern James bay have switched a bit to NORTHWEST behind a few fragmented/weak troughs, yet it looks like these winds are feeding directly into the weak low over Ottawa!
Saturday: other than a week trough, things are looking pretty relaxed on the weather front - enough to get the birders out and searching for pelagic vagrants.
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So? Did the Razorbill show up back on Thursday from the St. Lawrence, early and before the winds went SW?
Or did it arrive late on Friday from James Bay, a poor lost little seabird doing an overland flight to find real salt water again? -- and eventually dropped in Ottawa as the wind blew it to the centre of the low pressure?
I don't really know :) But it was fun to look at the maps anyways.
*** disclaimer *** my interpretation of the maps is pretty much guesswork, as I've never really studied weather with someone who knows what they're doing.
One of the several Gannets I've seen in Ontario. Such an odd bird to have here pretty much annually.
Brandon,
ReplyDeleteInteresting take on the possible origins of these two birds. I was recently discussing the Gannet sightings in Alaska with some birders from there and as far as I know, it was never clearly determined that they were Northern Gannets. All things considered, it seems more than possible that Australasian Gannets would have made a long but entirely unobstructed detour from their regular haunts in the S. Pacific.
The Northwest Passage is not a very likely conduit for birds travelling between the Atlantic and Pacific - especially pelagic ones. Even at the best of times large areas are choked with ice, much of the water is more or less devoid of any kind of food (particularly fish) and generally speaking there is no clear 'path' for birds to follow.
As far as Gannets and Razorbills in the Great Lakes go, there is a clear tendency for both species to undertake post-breeding movements down the St. Lawrence and even into the Great Lakes. There are numerous historical records of large wrecks of Dovekies as well. Both Gannets and Razorbills are fairly common in the fall as far W as Tadoussac, only 800 km from central Lake Ontario.
Both Razorbill and Northern Gannet breed in significant numbers within the St. Lawrence estuary and there is absolutely no barrier between any of the large colonies within 1,200 km of Lake Ontario, while even the shortest possible route between any of those colonies and Lake Ontario through James Bay (minimizing over-land flight to N. Ontario) is over 5,000 km.
Both Gannets and Razorbills are highly pelagic birds which practically never fly over land. That a wandering bird would undertake an 800 km+ flight over solid boreal forest from James Bay to end up in Lake Ontario seems a bit unlikely.
Finally, Lake Ontario is by far the most 'popular' destination for these species which makes sense since it connects directly with the St. Lawrence (no doubt this is the route taken by virtually every single vagrant seabird to show up there including the albatross!). If seabirds were crossing from James Bay, Lake Superior and Lake Huron would be far more likely places to find them. Differences in observer effort aside, I think it is pretty safe to assume that the number of birds that would wander out of the Atlantic into Hudson Bay is minimal, and the number that would end up crossing Ontario from James Bay into the Great Lakes is probably practically none.
Having said that, there is considerable anecdotal evidence to suggest that some arctic breeding species, particularly jaegers, Glaucous and Sabine's Gulls regularly 'cut through' Hudson Bay and the Great Lakes on their way to the Atlantic, and they are frequently seen further inland than one might reasonably expect.
Awesome trip report from James Bay, by the way!