The ebb and flow of spring migration

Like a great tidal wave, bird migration in spring can wash over the land and fill every twig, bough, and branch with birds. Or it could retreat and leave you straining your eyes and ears for a sign, a song, a feather. It is the typical boom and bust linked with local, regional, and continental weather patterns.

The last week was a prime example here at Cabot Head: a few busy days were interspersed with quiet and cold days. On May 6, we banded once gain more than a hundred birds: what is usually a rare event seems very ordinary this spring! There were 51 Ruby-crowned Kinglets banded among the total of 114 birds of 17 species, including the FOY Blue-headed Vireo. The following day was the ebb, with only 18 birds banded. Very few birds were around, but we had the FOY Orange-crowned Warbler in our nets, FOY Ruby-throated Hummingbird, and in the afternoon a delightful cloud of swallows raking the air above Wingfield Basin, feeding on the aerial plankton (yes! These are actual terms and not the lyrical prose of an inflamed mind stretching the nautical metaphor). There were about 60 Tree Swallows, spiced up with one Northern Rough-winged Swallow, one Bank and two Barn Swallows.

On May 8, World Migratory Day, the cold and windy weather reminded us that early May can be bitter even in the extreme south part of Canada. Despite all nets open for the normal 6 hours, the haul was a meagre 25 birds with very little activity in the trees. The waterfowl traffic over Georgian bay was steady and constant however with a total of 74 Common Loons (in ones, twos, and threes) and one Red-throated Loon, 73 White-winged Scoters in a few flocks, 73 Red-breasted Mergansers in fast and furious little groups (this species is the fastest duck under the sky – or over the water). We also detected in smaller numbers Long-tailed Ducks, Buffleheads, American Wigeons, and Greater Scaups. One lone Common Tern was briefly spotted by Danielle in early morning.

May 9 dawned clear and cold, with nets opened at 5:45am as usual. It was quiet for the first three hours or so but with warming temperatures, it changed suddenly when several waves moved through, filling up the nets quickly. At the end of 6 hours, we did not break the 100-bird barrier but got very close, with 92 birds banded of 18 species. Once again, Ruby-crowned Kinglets got the crown (bad pun sadly intended) with 28 birds but the Palm Warbler was a close second with 24 birds banded. Despite very little time to observe, a FOY Black-throated Blue Warbler was seen, one of the 11 species of warblers detected that day, the highest total so far. 

Oddly no American Redstart has yet been seen this spring, as I write these lines on May 11. Between 2002 and 2019 (monitoring in spring 2020 was Covid-impacted, so cannot be easily compared), the first detections of American Redstarts were between May 8 and 10 every year, except for two early spring seasons (May 2 in 2013, May 4 in 2010) and three late years (2002, 2004, and 2017, May 13 being the latest on record).

Not many birds were seen or heard on May 10 & 11, under a persistent cold West wind: warmth will eventually return to the land, spring will continue its slow greening, and American Redstarts will again fill the woods and thickets with its crystalline song.