CEDAR GROVE - One moment the November sky above Cedar Grove Ornithological Research Station was an inert cobalt canvas streaked with a few white cirrus clouds.
The next a buff-colored speck soared over the northern tree line and everything changed.
Danny Erickson of Wauwatosa and Jenn Schneiderman of Madison grabbed binoculars and looked out of the facility's viewing slot to parse out clues on the fast-approaching mass of feathers, muscle and talons.
"Redtail," said Erickson, CGORS' banding director. "Keep coming, keep coming..."
The raptor saw a potential meal on the open field below and set its wings in descent.
Seconds later it landed and was captured in a remote-controlled net.
Schneiderman sprinted across the grass to secure the flapping hawk and brought it inside for processing.
"An adult!" Schneiderman said as she presented the bird to the other staff on hand. "And isn't she beautiful?"
Moreover, the bird was exactly the age and species researchers at the station hoped to capture, fit with a high-tech transmitter and release as part of a new Red-Tailed Hawk Project being run by Bryce Robinson of Cornell University.
Cedar Grove Ornithological Research Station got its start as a bird banding site in 1935 under the auspices of the Milwaukee Public Museum with assistance from the Civilian Conservation Corps.
In 1950, Milwaukee natives Dan Berger and Helmut Mueller took over and ran it for more than 60 years. It's now run by the CGORS board of directors, volunteers and a few paid staff.
It could well be the most important Wisconsin bird study site you've never heard of.
The station has the longest sustained record for observations and trapping of birds of prey in North America.
Since its inception, 45,516 birds, mostly hawks and owls, have been captured, banded and released at the facility.
The work is conducted from Aug. 15 to Nov. 15 each year in a modest building set on 31-acres of Department of Natural Resources land near the Lake Michigan shore in Cedar Grove.
Because of the nature of the work, the property is closed to visitors unless arrangements have been made in advance.
Prevailing westerly winds cause migrating birds of prey to concentrate near Wisconsin's Lake Michigan shore as they move south.
As such, CGORS is perfectly situated for raptor research studies.
This year the CGORS crew caught, processed and released 788 birds of prey, including 334 saw whet owls, 175 sharp-shinned hawks, 131 red-tailed hawks, 73 merlins, 42 Coopers hawks, 17 peregrine falcons as well as a few each American kestrels, short-eared owls and northern harriers.
The birds are fitted with metal bands and the data are entered in a U.S. Fish and Wildlife Service system. If a band is recovered, mostly when a bird is found dead, or if it's captured at another site, the physical tag can help fill in some blanks about bird movements or life history.
But that technology dates back several centuries.
That's why CGORS decided to work with the Red-tailed Hawk Project, said Suzanne Kaehler, board member and volunteer at the facility.
Attaching a GPS transmitter to a bird allows researchers to obtain locational data around the clock, yielding a far richer and more complete catalog of information.
"Redtails may seem common," Kaehler said. "But we actually don't know that much about them."
The species is native to Wisconsin and, since it can live in a range from urban to rural to natural habitats, is doing fairly well.
Indeed, if you see a hawk perched along a highway in the Badger State, odds are it's a redtail.
But is it a resident hawk in its year-round territory? Or a migrating bird taking a rest?
In Wisconsin, it could be either.
The Red-tailed Hawk Project is working across North America to study the species, said Robinson, a doctoral candidate at Cornell who is coordinating the research.
The two main pillars of inquiry are evolutionary history and movement ecology.
"We have many unanswered questions," Robinson said. "Modern technology is, we hope, going to be a big assist in answering them."
As part of the work, researchers are attaching the GPS transmitters to the birds as well as taking blood samples for genetic testing and recording images of the individuals to help with phenotyping.
The solar-powered transmitters store locational data and download it whenever in range of a cellular phone tower. The technology allows researchers to construct a nearly 24/7/365 record of the birds' movements.
Red-tails are found from Alaska and across northern Canada down to Panama and into the Caribbean.
Literature describes 16 subspecies of redtails, Robinson said.
But due to color types and other variations, it's not clear where to draw many of the lines.
Among questions the work will attempt to answer: Is the Harlan's redtail found mostly in Alaska actually a separate species? And is the Krider's redtail, a beautiful, lighter-colored bird found mostly in the northern plains region, a distinct subspecies or simply a blonder variation of the more common redtails found in the Midwest and East?
About 30 transmitters were attached to redtails in 2020 and another dozen or so are being deployed this year, Robinson said.
Already "full cycle" information over the last year has revealed breeding sites in Alaska and northern Canada for some birds that fly south for the winter as well as identified other birds in the U.S. that are non-migratory.
It's also helped document behaviors of the species, such as the brooding period when male redtails fly widely to hunt and supply food for the females. During this time of "provisioning" by its mate the females stay on or very close to the nest.
Robinson has enlisted researchers across the continent to participate in the study, including Nick Alioto at Michigan State University, Lucas DeCicco at University of Kansas, Allie Pesano at University of Minnesota Duluth and Hawk Ridge Bird Observatory, Neil Paprockie at University of Idaho, Nicole Richardson, Mark Robbins at University of Kansas Museum of Natural History, Brian Sullivan at Cornell Lab of Ornithology and Jesse Watson at HawkWatch International.
When Kaehler heard about it, she knew CGORS could be an ideal cooperator.
She contacted Robinson and organized the fledgling partnership.
Funding for the four transmitters (about $1,500 each) came from donations from Madison Audubon, Jim and Suzanne Otto and Kaehler.
They are the only transmitters attached to redtails in Wisconsin as part of the work.
Robinson visited the Cedar Grove facility in October to conduct training on the transmitters and other aspects of the project.
The goal is to place the tracking devices on adult redtails so data would help reveal breeding sites and migration information, if appropriate.
That's why although the CGORS crew is excited each time it bands a raptor, the adult with the rust-colored tail carried into the facility by Schneiderman that November morning generated a special buzz.
Erickson, the banding director, and Kaehler placed a hood over the bird to calm it.
Then they measured its tail and wing feathers, talons and beak.
It was then weighed (1,088 grams) and a 1 milliliter sample of blood was drawn.
Two snippets of feathers were cut, too, to assist with isotope studies.
The bird was then taken outdoors for a photo session with special attention paid to feather colors.
"Just look at those pantaloons," Schneiderman said, admiring the feathers on the hawk's legs.
Then came time for the GPS transmitter to be attached. The device, about half the size of a deck of playing cards, fit on the bird like a backpack.
A special adaptation has been added to the redtail transmitters this year: the solar panel has been raised about 1/4 inch from the main unit to help it extend above the bird's feathers and improve its access to sunlight for charging.
Once Erickson and Kaehler were convinced the unit's straps were tight enough to hold but loose enough for the hawk to fly and move normally, it was time for release.
Schneiderman carried the bird, now called Rosie, into the woodlot on the south of the property.
She held the hawk at shoulder height and with a slight boost, she let go of its legs.
The redtail didn't miss a beat. It soared once more, up and away to the south.
This time though its movements will add to the body of science and perhaps one day even help protect its species.
More information: Cedar Grove Ornithological Research Station is a non-profit, mainly volunteer group dedicated to raptor research. Donations can be made to P.O. Box 156, Glenbeulah, WI 53023 or via PayPal to email@example.com.
You can also donate to the Cedar Grove Ornithological Research Station Fund established by the Natural Resources Foundation of Wisconsin. Visit wisconservation.org to learn more.
To learn more about the Red-tailed Hawk Project, visit redtailedhawkproject.org.
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This article originally appeared on Milwaukee Journal Sentinel: Hawk study in Wisconsin seeks to unlock secrets of redtails