BY JEROME S. JOURDAN
The Great Lakes form a natural barrier to raptor migration. Thermals, or pockets of rising heat, provide buoyancy to raptors and vultures that allow them to soar for hours without flapping their wings. These thermals disappear over open water, thus requiring raptors to avoid open-water crossings as much as possible.
Migrating raptors from Canada are forced to pass to the west or east of the Great Lakes before heading south across the U.S. to their wintering grounds in Mexico, Central and South America. For those birds traveling the east around the Great Lakes the region of Gibraltar, Mich. and Essex, Ont. host some of the largest flights of raptors north of the Mexican border.
Thanks to the volunteer efforts of dedicated hawk watchers, The Detroit River Hawk Watch has become recognized as one of the top hawk watch sites in North America. With annual fall counts of almost 130,000 raptors the annual fall migration through the Gibraltar hawk site is highlighted by spectacular kettles of approximately 70,000 broad-winged hawks and 50,000 turkey vultures. With additional thousands of red-tailed and sharp-shinned hawks, plus hundreds of eagles, harriers and falcons the Detroit River Hawk Watch is a premier destination for raptor enthusiasts and photographers.
“Detroit River Hawk Watch is the premier citizen science initiative of the Detroit River International Wildlife Refuge,” said Dr. John Hartig, refuge manager.
It is a partnership among the U.S. Fish and Wildlife Service, the International Wildlife Refuge Alliance (the Refuge’s Friends Organization), Huron Clinton Metroparks, and the Detroit River Hawk Watch Advisory Committee. Raptor count data are entered into a North American database (hawkcount.org) managed by the Hawk Migration Association of North America.
On any given day between Sept. 1 and Nov. 30 the skies over Gibraltar could fill with large kettles of migrating hawks or vultures, or steady streams of accipiters, buteos, falcons and eagles. The highlights of this Hawk Watch are the tens of thousands of broad-winged hawks and turkey vultures that migrate seasonally through the region. Numbers are only surpassed by those from southern count sites like Galveston, Texas or Veracruz, Mexico. Hawk Watch numbers correlate well with those from Holiday Beach Hawk Watch just 9.4 miles away in Ontario.
Sixteen species of accipiters, buteos, falcons, eagles and vultures have been recorded at Detroit River Hawk Watch. During the month of October it is possible to record all 16 species in a single day. The highlight of the count is the tens of thousands of broad-winged hawks and turkey vultures that pass through the region each fall. On Sept. 17, 1999, a staggering 543,533 broad-winged hawks, 3263 sharp-shinned hawks, 336 American kestrel, and 14 peregrine falcons were recorded by Jeff Schultz, Vic Berardi and Tim Smart (hawkcount.org).
The success of the Detroit River Hawk Watch would not be possible without the dedication of volunteers who log hundreds of hours counting hawks in all weather situations. Support from the U.S. Fish and Wildlife Service, the International Wildlife Refuge Alliance, Hawk Migration Association of North America, and the Huron Clinton Metroparks has been essential. Volunteers are always welcome and visitors are urged and invited to come out to the boat launch at Lake Erie Metropark to join in this compelling citizen science effort.
Jerome S. Jourdan is a member of theDetroit River Hawk Watch Advisory Committee.