Peak warbler has happened!

The tropical push kept going on May 13 when migrant waves washed upon the shores of Georgian Bay at Cabot Head: it was another successful day of banding and observing. A total of 74 species were counted, including 18 species of warblers, the highest single-day total for this much beloved group of birds! Likewise, the banding total reached 86 birds of 25 species that day, the highest single-day total for the season thus far. Interestingly, the species we banded the most of was the Palm Warbler, with 23 individuals caught in our nets.

A denizen of boreal bogs and fens, Palm Warblers arrive early at Cabot Head, in late-April, but usually peak around early- to mid-May. In Ontario, most Palm Warblers breed in the far North, notably in the Hudson Bay Lowlands. It winters mainly in the Southeast USA and the Caribbean. This is how it gets the “Palm” component of its name!

Migration continued in force for the following several days with a colourful suite of warblers, the cherished mid-May jewels of winter-dreary birders. On May 17, there were a few other new arrivals to the scene: Mourning and Canada Warblers, Eastern Towhee, and Clay-colored Sparrow (the latter caught in nets). Banding totals showed the typical boom-and-bust of migration: after the high of 86 birds on May 13, totals dropped to 14 birds the following two days, before rebounding to 65 birds on May 16.

And then, the wind came! A very strong South wind brought an early taste of Summer to the station, with temperatures reaching 27°C, a welcome change for all. But the wind blew, unabated, for two full days, precluding any banding and reducing bird movements to a minimum. Migrants appreciate a tail wind during their journeys, but there is a limit in how strong the wind can be.

After basking in warm weather for two days, there was a dramatic shift in wind direction: on the dawn of May 19, a North wind blew over the bay, bringing temperatures down to 4°C! As a consequence, very few birds were observed and captured. And we all scrambled to bundle up in warmer clothes once again! The cold weather continued the following day, despite a shift in the wind to the East, a harbinger of a depression coming. And indeed, on this Sunday morning, rain has arrived and is falling heavily under an overcast sky. There will be no banding today and few, if any, migrants pushing their way Northward.