Migration along the Atlantic Flyway through Canada is not a single, uniform movement. Different taxonomic groups migrate at different times, use different habitats, and respond to different environmental cues. Understanding the structure of this movement — by species group and by timing — makes it possible to predict what will be present at a given site in a given week.
The flyway concept was formalized for waterfowl management purposes by the U.S. Fish and Wildlife Service in the mid-twentieth century. While waterfowl flyways remain the primary regulatory framework for migratory bird management, the Atlantic Flyway as an observable phenomenon applies to a much broader range of species. The Government of Canada's migratory bird sanctuary network provides protected habitat at key stopover sites along the corridor.
Flyway Geography Through Eastern Canada
The Atlantic Flyway in Canada runs from the northern breeding grounds in Nunavut and Labrador southward through Quebec, Ontario, New Brunswick, Nova Scotia, and Prince Edward Island. The corridor compresses at geographic bottlenecks — the tip of Point Pelee in Ontario and the funnel of Nova Scotia — producing high bird concentrations at these sites during migration peaks.
The St. Lawrence River corridor functions as both a travel route and a stopover habitat for waterfowl and shorebirds. The Bay of Fundy, with its extreme tidal range, creates extensive intertidal mudflat habitat that serves as a critical stopover for shorebirds — particularly Semipalmated Sandpipers — during southbound fall migration.
Waterfowl Migration
Canada Goose (Branta canadensis)
The most familiar waterfowl migrant in Canada. Multiple distinct populations of Canada Geese use the Atlantic Flyway — from the small-bodied Cackling Goose (recently split as a separate species) to the large-bodied Giant Canada Goose. Spring migration begins in February in southern Ontario and reaches northern Quebec and Labrador breeding grounds by May. Fall movement southward begins in September.
Resident populations of Canada Geese have expanded considerably in urban and suburban areas across southern Canada, creating year-round populations that complicate the observation of migratory individuals moving through on schedule.
Greater Snow Goose (Anser caerulescens atlanticus)
Nearly the entire world population of Greater Snow Geese stages on the tidal mudflats and marshes of the St. Lawrence estuary during spring migration, creating one of the most impressive concentrations of large waterbirds in North America. Cap Tourmente National Wildlife Area, east of Quebec City, is the primary staging site, with numbers peaking in late April and early May. The fall concentration is less dramatic but still substantial, occurring primarily in late October.
Arctic Tern — breeding in coastal Atlantic Canada, this species undertakes one of the longest migrations of any bird, reaching the Antarctic. Photo: Wikimedia Commons / CC BY-SA 2.5
Shorebird Migration
Shorebird migration through the Atlantic Flyway involves two distinct movements: the rapid southbound movement in July and August, led primarily by adults, followed by a second wave of juveniles in August and September. Northbound spring migration in May is less concentrated and generally involves smaller numbers at individual sites.
Semipalmated Sandpiper (Calidris pusilla)
The dominant shorebird species in the Bay of Fundy concentration, with documented counts in the hundreds of thousands at peak staging periods. These birds arrive from breeding grounds in the Canadian Arctic and Subarctic, feed intensively on the abundant amphipod crustaceans in Fundy intertidal flats, and then depart on a non-stop transoceanic flight to the northeastern coast of South America.
Research published through the Western Hemisphere Shorebird Reserve Network has documented the Bay of Fundy's hemispheric importance as a shorebird stopover site. Fuel deposition rates at Fundy sites allow birds to roughly double their body mass before departure.
Red Knot (Calidris canutus)
A medium-sized sandpiper with a striking brick-red breeding plumage. Red Knots breeding in the Canadian High Arctic use both the Atlantic and other flyways on southbound migration. The rufa subspecies, which winters in Tierra del Fuego and migrates along the Atlantic coast, has experienced documented population declines linked to reduced horseshoe crab egg availability at key Delaware Bay stopover sites in the United States.
Raptor Migration
Raptors concentrate at geographic features that allow efficient soaring — ridgelines, coastlines, and peninsula tips. In eastern Canada, several sites produce consistent raptor counts during autumn migration.
Broad-winged Hawk
Buteo platypterus
Peak movement in mid-September, with large kettles — sometimes thousands of birds — visible at hawk watch sites. The broad black-and-white tail bands and stocky shape distinguish it from other buteos. Essentially the entire eastern North American population passes through the flyway within a two-week window.
Sharp-shinned Hawk
Accipiter striatus
Canada's smallest accipiter and the most numerous raptor migrant at coastal hawk watch sites. Peak movement in late September and October. The small size, rounded wings, and square-tipped tail separate it from the larger Cooper's Hawk, though the two species can be very difficult to distinguish at distance.
Red-tailed Hawk
Buteo jamaicensis
The most broadly distributed buteo in North America, present year-round in southern Canada and moving southward in variable numbers each fall. The rufous tail of adults — visible from above as they soar — is the primary field mark. Multiple colour forms occur across the continent.
Northern Harrier
Circus hudsonius
Recognized in flight by the white rump patch, long tail, and low quartering flight over open ground. A common fall migrant at coastal sites and inland marshes. Males are grey; females and immatures are brown with streaked underparts.
Red-tailed Hawk — frequently observed at hawk watch sites during Atlantic Flyway autumn migration. Photo: Wikimedia Commons / CC BY 2.0
Passerine Migration
The largest number of individual migrants in the Atlantic Flyway are passerines — songbirds, sparrows, thrushes, and warblers that move through in waves driven by weather systems. Strong cold fronts with northerly winds in September and October push large movements southward overnight. The morning after a front often produces "fallouts" — concentrations of exhausted birds at the first available cover, particularly at coastal woodlots.
Warbler Movement
Spring warbler migration through Ontario and Quebec peaks between May 10 and May 25, with eastern Canada receiving a large proportion of the continent's breeding warbler population as birds disperse northward to boreal and mixed forest breeding sites. Point Pelee National Park in Ontario records upward of 35 warbler species during peak spring movement, concentrated by the peninsula's southernmost position extending into Lake Erie.
Fall warbler migration is more protracted, beginning in late July with post-breeding adult Yellow Warblers and continuing through October with late-moving Yellow-rumped Warblers and Palm Warblers.
Timing Summary
| Bird Group | Spring Peak (Northbound) | Fall Peak (Southbound) |
|---|---|---|
| Waterfowl | March – April | October – November |
| Shorebirds | May | July – September |
| Warblers | May | August – October |
| Raptors | March – April | September – November |
| Sparrows and thrushes | April – May | September – October |
| Waterfowl (geese) | February – March | October – December |
Observation Planning
Effective use of the Atlantic Flyway for observation depends on timing, weather monitoring, and site selection. Weather-driven movements are best anticipated by watching for cold fronts in October and November — the morning after a front with clear skies and northwest winds typically produces high raptor and sparrow counts at watch sites. For shorebirds, tidal stage matters considerably at mudflat sites; incoming tides concentrate birds at accessible viewing distance before pushing them off the flats.
The Meteorological Service of Canada weather forecast tools are standard resources for predicting migration-driving weather events, alongside community-maintained eBird rare bird alert systems that notify observers of notable species as they appear.