Motus Towers: A new way to use older technology to understand migration

How can we look at migration routes in real-time without satellite transmitters and without having to recapture the units? By using old fashioned radio telemetry!

Motus, the Latin word for movement, is the name of a new way to use older technology to effectively track the migration of wildlife. With the changes in day-length and food-source cycling, birds begin to feel the urge to move. The zugunruhe, nocturnal restlessness in songbirds near migration, takes hold and they begin their treacherous journeys south in search of food-rich wintering grounds, only to make the same perilous trip again in the spring when North America explodes into life with a bounty of insects to feed their young.

Tracking migrating birds can be very difficult, especially when they only weigh as much as a couple of quarters. Current satellite technology can allow us to follow animals migrating in real-time, but the weight of this technology is too heavy for many smaller animals. Banding birds can be a great way to study migration. However, one must band thousands of birds to successfully recapture a few individuals and ultimately gather data to learn about each individual’s journey or destination. When we do successfully retrieve a band number, it often provides only two data points: a location where the bird was first banded, and a location somewhere between its breeding range and wintering grounds.

Unlike bands, geolocators provide more information about where these birds go during migration. The issue with geolocators is that the bird must survive the entire journey and make it back to where the geolocator was deployed. Then, you must recapture that bird to get the unit off and download its data. That’s a lot of obstacles to overcome to get the information back, but when you do, it can be very enlightening and exciting! 

So, how can we look at migration routes in real-time without satellite transmitters and without having to recapture the units? By using old fashioned radio telemetry!

Radio telemetry uses radio signals and receivers to track birds. Small nanotag transmitters are temporarily attached to birds, bats, butterflies, or even dragonflies. These transmitters send out a signal a few times every minute that can be picked up by a receiver along the way, specifically a Motus tower. These towers have antennas that can pick up the signal from a tagged individual if they fly within a few kilometers of a tower. Staging these towers along migration routes creates a virtual net to capture the animals' information. Imagine having check-points along migratory routes to see which path they’re taking. These towers connect to the internet and download tag ID numbers as they are detected in real-time, giving the researchers who deployed these tags the whereabouts of the bird as the individual migrates. The towers are the perfect blend of old and new technologies to make understanding the mysteries of migration more affordable, comprehensive, and collaborative with a wide range of hosts and partners deploying tags and hosting towers. The result is a better understanding of the full life cycles of imperiled migratory species in a cooperative scientific approach.

Audubon South Carolina is teaming up with the South Carolina Department of Natural Resources (SCDNR) and Bird Studies Canada to create a network of towers through our bird-friendly communities, chapters, and centers. The Dewees Island Conservancy on Dewees Island, one of our Bird-Friendly Communities, had the first tower to go live in our ASC Motus Tower network.

“We are so excited about the potential to use this scientific tool to tell the story of an individual bird:  where it was banded, where it has gone from here and how long it took to travel,” said Judy Fairchild with the Dewees Island Conservancy.

The Charleston Audubon and Natural History Society is partnering with The National Park Service and the South Carolina Department of Natural Resources, to install a tower at the Fort Moultrie Visitors Center which is part of the Fort Sumter National Monument.

This tower will be accessible to the public and will include an interpretive sign for visitors. We are pleased to share that Daufuskie Island’s tower is near completion and will soon go online as well.

Currently, there are towers in the planning phase on Fripp Island, Harbor Island, Spring Island, Hilton Head, Francis Beidler Forest, and Silver Bluff Audubon Sanctuary as well. 

For more information on why we need to study the full life cycle and migration of birds and how this technology works, visit: If you’d like to make a donation, please click here to support our ongoing research efforts.  Check out the detections that the Dewees tower has picked up lately, with migration getting into full gear some neat birds are passing by!

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