The wonder of spring migration is playing out across much of the globe as millions of birds are shifting from wintering to breeding grounds.
The annual cycle is a matter of survival for most species — they must escape cold and snow and spend winter in a more hospitable location where they can find food and shelter.
And now, as hours of daylight increase and the temperature warms in the Northern Hemisphere, it’s time to travel once more.
As they fly north this spring, some of our feathered friends will be adding critical data to the understanding of their migratory paths and habitats.
The birds are among tens of thousands fitted with tiny transmitters as part of the Motus Wildlife Tracking System.
Some, including species with relatively poorly understood migratory paths, could be passing through your Wisconsin neighborhood any day.
“It’s eye-opening to me what is still being learned,” said Jennifer Phillips-Vanderberg, executive director of the Western Great Lakes Bird and Bat Observatory near Port Washington. “Motus is definitely helping us answer some questions as well as helping us ask better ones.”
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Phillips-Vanderberg is among a cast of thousands who help coordinate Motus, an international collaborative research network run by Birds Canada.
The program uses an automated radio telemetry array to track the movement and behavior of small flying animals, mostly birds but also bats, butterflies and dragonflies.
The transmitters are fitted on the animals like tiny backpacks; they are battery- or solar-powered. Each tag has a unique signature, similar to a “chip” in a domestic dog or cat.
The signals are picked up by 1,346 Motus receivers in 31 countries on four continents, most in North America.
Wisconsin has 12 active receivers, including at Afterglow Farm near Port Washington and at the Milwaukee County Zoo in Wauwatosa.
As a tagged animal flies within range of a receiver, a computer records the data.
The system can determine the location of the “hit,” the speed of travel and how long the animal stays in the area.
The data is then centralized at the Birds Canada National Data Centre, where it is filtered, analyzed, archived and disseminated to all researchers and organizations in the network. The public, too, can view the results on motus.org.
The purpose of Motus is to facilitate landscape-scale research and education on the ecology and conservation of migratory animals.
Scientists have long known the health of most migratory species remains on a triumvirate of habitat needs: breeding, wintering and migratory, or stopover.
As human development and resource use continues apace it’s becoming more important each year to determine birds’ exact travel routes and stopover sites.
Habitat bottlenecks occur for many species on their migratory paths; if the most critical chunks can be saved and protected, it could prevent a species from becoming endangered, Phillips-Vanderberg said.
Davor Grgic, a Wisconsin Society of Ornithology board member who lives in Sheboygan, volunteers to extract the data twice a year from Motus receivers in southern Wisconsin so it can be uploaded to the international system.
Information from Motus towers in Wisconsin has yielded many surprises. One of the most unexpected was Swainson’s thrushes from western British Columbia flying through the Badger State on their fall migration, Phillips-Vanderberg said.
“These birds flew over the Rockies and across the Great Plains and then south along Lake Michigan,” Phillips-Vanderberg said. “Later, one was detected in South Carolina and Florida on the way to Central or South America. It’s such an amazing journey.”
It would have been easy to assume Swainson’s thrushes seen in Wisconsin were only birds that nested directly north in Ontario. Now it’s known they could be from virtually anywhere in the breeding range.
Motus is also integral to a golden-winged warbler project being conducted in Wisconsin. That work, led by Amber Roth of the University of Maine, tagged several of the threatened warblers last summer near Rhinelander. The birds later were detected by Motus migrating through southeastern Wisconsin.
The researchers are hoping the birds will be detected coming north this spring.
To date 31,235 individuals of 278 species have been tagged worldwide as part of Motus.
The quest continues to add more receivers and tagged animals to the project, including in Central and South America, where birds that breed in Wisconsin spend the winter. Each receiver costs about $5,000 and each transmitter about $200, Phillips-Vanderberg said.
Phillips-Vanderberg recently submitted a grant proposal to help fund additional receivers in Wisconsin. The receivers, typically placed on roofs, have a range of about nine miles in optimal conditions.
She and other Motus collaborators await the 2022 spring migration as eagerly as any birder.
“The data Motus is gathering is so important,” Phillips-Vanderberg said. “And if we can continue to build the network, it will help make even more significant contributions to science and allow for better decisions to help birds.”