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September is the heart of our fall migration


Black-throated Blue Warblers are among the migrants that are flying through London in September. The plumage of the males of this species looks the same in the spring and fall. photo by Paul Nicholson.


While fall migration in and around London starts in late July with the appearance of some shorebirds and doesn’t end until early December when Snowy Owls reappear, the heart of fall migration is September.

We can now see some birds flying through Middlesex County on their way to their overwintering grounds, we will notice the disappearance of many local birds that bred here through the summer, and we welcome some species that will stay with us through the winter. With new birds arriving each day now, it makes all kinds of sense for feeder watchers and the keenest of bird watching listers alike to be especially observant.

The wood warblers are always among the favorite migrants of bird watchers. Almost all of these birds fly through during September. Some are relatively easy to identify. The well-named male Black-throated Blue Warblers look the same now as they did when they were flying north to the boreal forests in the spring. After having gone through a late-summer moult, some of the other warblers look much different in their basic plumage than in their spring breeding plumage. The Blackpoll for example looks completely different. This subset of warblers is known as the “confusing fall warblers” and it is part of what makes fall birdwatching a special challenge.

Apart from the warblers, September gives us the opportunity to enjoy many other fly-through migrants that we haven’t seen since the spring. Species as varied as Yellow-bellied Sapsuckers, Pectoral Sandpipers, and Olive-sided Flycatchers are on the move now. Keep your eye out for thrushes and early raptor migrants such as Broad-winged Hawks. Philadelphia, Blue-headed, and Yellow-throated Vireos can be seen in September as well.

It’s sometimes harder to notice the disappearance of birds that have spent their summers with us. Although a few tough individuals may hang back into October, most Ruby-throated Hummingbirds will fatten up on nectar in early September then head south by the end of the month. Most swallows and flycatchers including Eastern Kingbirds, Phoebes, and Pewees, will make their exits in September as well.

September also marks the arrival from further north of Golden-crowned Kinglets and Brown Creepers. They will over-winter in London. There are a few other of these arrivals. Watch and listen through the month for Winter Wrens, Merlins, and White-throated Sparrows.

Even though fall migration activity does peak in September, there is still plenty of action to look forward to in October and November. A few warbler species such as Yellow-rumped Warblers, Common Yellowthroats, Palm Warblers, and Nashville Warblers will persist into October. The movement of bigger hawks and the arrival of various duck species in the mid- to late-fall is always exciting.

As ever, the “Explore” features on the eBird Canada platform can be really helpful in seeing what birds are on the move at a particular hot spot. I find the bar charts for Middlesex County to be one of the most useful eBird features. And as ever, any of our local Environmentally Significant Areas or area Provincial Parks are great spots to bird watch now and through the fall.

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