New arrivals from the Boreal and beyond…

Imperceptibly, but inexorably, the season is slipping into Fall, with a slow change in leaf colour in the poison ivy and some shrubs, with a cooling of the night, and, with the arrival of new birds coming across Georgian Bay, from the vastness of their breeding range in the Boreal Forest.

The pace did pick up, at least for one day: on August 30, a total of 44 birds were banded, the highest total of the season so far. It included 12 Red-eyed Vireos, quite a good tally for a species that tends to stay high in the canopy and is not often captured in high numbers. In the previous 15 Fall seasons, there has been only five days when more than 12 Red-eyed Vireos were captured. Three of them were in 2005, a year when an abundant chokecherry crop brought lots of berry-eaters into our nets: beside Vireos, it was a “bumper” Fall for Yellow-rumped Warblers, Cedar Waxwings, and thrushes of various species.

The same day, August 30, there were also four Cape May Warblers captured, bringing the season total to 11 birds, the highest ever: totals have been between one and three birds, except in Fall 2015, when 7 Cape May Warblers were banded.

Other notable captures on August 30 were the first Bay-breasted Warbler of the season… and a Belted Kingfisher! The latter is captured from time-to-time (12 birds in the eight previous Fall seasons) but it is still a pleasant surprise.

Birds from the Boreal Forest kept arriving over the following few days as well: on August 31, a few Palm Warblers were seen on census, while one Gray-cheeked Thrush was captured. This species of thrush actually breeds north of the Boreal Forest, in subarctic brushy willow-alder thickets and low coniferous forests. It is the least studied thrush species in North America, mostly due to the remoteness of its breeding range: in Ontario, only two nests have ever been found!

On September 1, a true bird of the Boreal Forest – despite its name – appeared in our nets: one Tennessee Warbler was captured! As with a number of other warblers, it was named where it was first collected and scientifically described: Alexander Wilson named it when he found it in Tennessee on migration. In Summer, this species specializes its foraging on Spruce Budworm and responds quickly to outbreaks. However, on its wintering grounds of Mexico and Central America, it “steals” nectar by piercing flowers with its sharp beak. The other arrival of the day was a Swainson’s Thrush: this species is more abundant in the Boreal Forest, although some breed on the Bruce Peninsula. The Ontario Breeding Bird Atlas gives us some perspective: the Ontario population was estimated at 8 million birds, 6 million of which are found in the Northern Shield region and only 5,000 are found in the Lake-Simcoe Rideau region (which includes the Bruce Peninsula).

On September 4, under an overcast sky and strong South wind, a Blackpoll Warbler was seen briefly during census. However, the strong wind, and subsequent, intense showers, prevented any banding that day.

This Summer, the resident Eastern Whip-poor-will has not been as vocal as in previous years: it was finally heard for the first, and so far, only time during the night of September 1. One Blue-gray Gnatcatcher was heard, and then, seen on September 2. The following day, two individuals of this species were seen, detected once again, by their buzzy calls.

We are looking ahead at a week with potential precipitation for most of it: let’s hope that we will still manage to open nets and observe birds.

Posted in STATION NOTES / BLOG

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