While southern Ontario is sweltering, the weather on Grand Manan Island, in New Brunswick at the mouth of the Bay of Fundy, has been refreshingly pleasant: temperatures in the high teens/low 20’s, weak SW winds and lots of sunshine. Hmmmm…..let me qualify that: lots of sunshine above the fog banks that have been with us it seems daily since almost the beginning of August. But….the forecasters, also daily, avow that the fog will “retreat to the coast” during the course of the day. Which doesn’t do us that much good since we’re within a quarter of a mile of the coast.

As usual when we’re here, I set out 3 mist nets to sample the birds that live here or, at this time of year, migrate through here. The migration for shorebirds is in full swing: lots of Black-bellied Plovers, Semipalmated Plovers, Yellowlegs, and Least Sandpipers working over the exposed flats and gravel bars when the huge tide is out. They have been here since the beginning of the month. (I was seeing migrating Red Phalaropes hundreds of kilometers off the coast of Labrador and Newfoundland in July when I was doing seabird counts – these birds start early!)

But the movement of passerines, up until today (21st), has not been noticeable; in fact, their absence has been almost striking. This doesn’t mean that birds haven’t been around, it’s just that they’re not making their presence known – no singing and adults are not moving around much as they go through a complete feather moult at which time escape from predators is restricted….so it pays to be furtive.

But today was different. It started around 5 AM with the rain. The drumming on the roof woke me and I jumped out of bed to make sure the windows were closed. This rain continued until late in the morning. When it ended, Marg noticed that there were a LOT of small birds working their way through the alder scrub that surrounds our little cabin. I was about to head out to do a bird walk but, given this news, decided it might be better to open the nets. Good choice. In two and a half hours we caught and banded 70 birds, 68 of them warblers (of 11 species):

August 21st:
1 Red-breasted Nuthatch
1 Cedar Waxwing
35 Magnolia Warblers
1 Black-throated Green Warbler
6 American Redstarts
1 Nashville Warbler
4 Yellow Warblers
7 Chestnut-sided Warblers
7 Blackburnian Warblers
1 Northern Parula
1 Common Yellowthroat
1 Mourning Warbler
3 Black and White Warblers
1 Canada Warbler

Fog isn’t necessarily a deterrent to migrating birds. Flying at 300+ meters they are usually well above it and can easily see the stars which help them navigate. But when migrants in the air run into bad weather – rain and heavy cloud – they make landfall as quickly as possible. And when a large migrating front does this it is called a “fall out”. This is exactly what happened last night.

Follow-up on the 22nd:
Today small birds were noticeable but not in the numbers we were seeing yesterday. Many of the birds we encountered yesterday seem to have moved on. I opened the nets for 4 hours and caught and banded 20 birds:
8 Magnolia Warblers
5 American Redstarts
1 Yellow Warbler
1 Chestnut-sided Warbler
1 Blackburnian Warbler
1 Black and White Warbler
2 Canada Warblers
1 White-throated Sparrow (a local female still showing the remains of a brood patch and going through a complete moult)

The most exciting thing today though was to be able to witness Zugunruhe (my apologies to any German readers as there should be an umlaut on one of the u’s but my computer doesn’t do German….). Zugunruhe, or “migratory restlessness”, refers to a state of increased activity seen in birds before they set out on a migratory flight. Around 7 PM we began to see numerous warblers busily flitting through the trees, often chasing each other. They were moving too fast to be feeding. You could sense the excitement just watching them! Then, half an hour or so before sundown, it quieted down and you couldn’t find a bird. My take on this is that the birds found a safe perch and waited. What were they waiting for? Migrants determine their flight direction prior to takeoff based on the position of the setting sun and the accompanying polarized light. The birds were taking it in. Half an hour after sundown, if we could have seen it, we would have witnessed a huge movement of passerines into the skies, gaining height, and winging their way south. Call notes, sometimes audible from the ground, would serve to keep individuals together in loose flocks. [And no wonder they were so excited about getting going: last night (22nd) the fog cleared, the patchy cloud dissipated and brilliant stars studded the sky….showing the way.]

Rick