Counters stationed at the boat launch in Gibraltar's Lake Erie Metropark have been watching the sky fill with birds of prey this month, as the Detroit River Hawk Watch tracks one of its busiest stretches of the fall migration. Over the past week, the count topped 70,000 broad-winged hawks moving through the corridor, with single-day totals reaching into the tens of thousands.
According to FOX 2 Detroit, counters recorded nearly 36,000 broad-winged hawks on September 18, followed by 31,963 on September 21 — a drop of about 4,000 birds between the two days. The Detroit River Hawk Watch tracks birds of prey migrating south over southeast Michigan, with the annual count calculating how many raptors pass overhead each season. The watch is located at the Boat Launch at Lake Erie Metropark, where the Detroit River drains into Lake Erie, according to the station's report.
A Corridor Built for Migration
The lower Detroit River becomes a corridor for migratory birds each autumn, concentrating hundreds of thousands of raptors as they funnel south, according to the Detroit River Hawk Watch. Broad-winged hawks in particular gather over the lower river each September before continuing on toward wintering grounds in South America, with tens of thousands passing overhead in a single season. The site notes that migrating hawks use the area as a launchpad over Lake Erie, following wind patterns and local geography rather than fighting a straight path south.
Hawks frequently travel in the wake of a cold front, riding columns of rising heat called thermals to gain lift and cover long distances without flapping their wings, per the same account. That energy-saving strategy is part of why single days can produce such dramatic swings in numbers — a calm day might bring a trickle, while a well-timed front can send tens of thousands streaming past at once.
Counting Birds by the Dozens, Not the Bird
Tallying that volume of birds requires its own method. Hawk counters tally passing birds by twos, tens or fifties depending on how tightly they cluster, per an advisory committee member cited by FOX 2 Detroit, counting each bird as it crosses the channel. Kevin Arnold, cited in that same report, said it was prime time for birds to come through — a fitting description given the swelling counts logged this month.
The Detroit River Hawk Watch is a standardized monitoring program run by the U.S. Fish and Wildlife Service, the Detroit River International Wildlife Refuge and its friends group, the International Wildlife Refuge Alliance, at Lake Erie Metropark in Gibraltar. The 2026 season marks the program's 44th year, according to metroparks.com, which notes the site is staffed daily by trained counters from September 1 through November 30 unless severe weather cancels the watch.
What's Passed Through So Far, and What's Still to Come
Beyond broad-winged hawks, counters this season have spotted northern harriers, turkey vultures, bald eagles, sharp-shinned hawks, American kestrels and a Cooper's hawk moving through the corridor. September migration typically includes osprey, sharp-shinned hawks, broad-winged hawks, Swainson's hawks and American kestrels, per metroparks.com, with females of the osprey population usually the first to leave Michigan in August, followed by adult males in September and young birds through October.
October tends to widen the variety, bringing red-shouldered hawks, red-tailed hawks, Cooper's hawks and turkey vultures through the region. November is reserved for the rarities — golden eagles, northern goshawks and rough-legged hawks among them — with some of that month's migrants traveling from the furthest northern reaches of Arctic Canada. Averaging roughly 120,000 raptors from 16 species each year, the count has swung widely from season to season: 79,317 raptors in 2024, more than 150,000 in 2025, and 215,444 in 2023, according to detroitriverhawkwatch.org.
Those numbers feed directly into research well beyond Gibraltar. Hawk Watch counts help scientists and community members observe trends and patterns in species and populations over time, per metroparks.com — data that becomes more valuable the longer the daily counts continue. Huron-Clinton Metroparks has previously described just how extreme a single day of broad-winged hawk migration can get, with one official telling The News-Herald that some days bring tens of thousands of birds, and that the record from the early 1990s topped half a million hawks in a single day.
