New Tracking Data Uncovers Sandwich Tern Migration Mysteries
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Royal and Sandwich Terns have been nesting in North Carolina for decades, but little is known about their foraging habits during the breeding season, the route they take to get to their wintering grounds, or the timing of these movements.
That’s why we partnered with Dr. Kate Goodenough, lead ecologist at Larid Research and Conservation—to get a glimpse at their full annual life cycle, which will help guide conservation and restoration initiatives.
This year, five Sandwich Terns returned to breed on the Cape Fear River with trackers ready to transmit thousands of data points to the base station set up on Ferry Slip Island, where they spent this year’s nesting season. Here’s what they brought back.
One tern’s journey to Peru
We know that Sandwich Terns that nest on the east coast travel to South America for the winter because of our long-term effort to band chicks and document resightings. But we’ve never documented the exact route these birds take to get to their overwintering destinations. The data we collected this year began to unravel those mysteries.
This was especially true for one Sandwich Tern who slowly migrated south along the coast last fall towards Honduras and Panama, before making the jump to Ecuador, and finally Peru. It spent the winter at Paracas National Reserve, a 335,000-hectare marine wildlife area about the size of Rhode Island.
“The reserve is an extremely important stopover and staging area for a great diversity of long-distance shorebird migrants and now we know that one of our North Carolina terns is among those visitors,” Goodenough added.
It wasn’t chance that drew this tern to Paracas, but the nutrient-rich underwater current that makes this reserve one of the most biologically diverse areas in Peru. Known as the Humboldt Current, this cold underwater highway flows northward along the Peruvian coast and collides with the Paracas National Reserve, pushing nutrients up towards the surface of the ocean.
This nutrient-rich water provides the perfect foraging grounds for all kinds of wildlife, including our North Carolina Sandwich Tern. The tern spent four months traveling along the coastline of Peru before returning to our shores this spring.
The Return of the Terns
We now have three seasons of Royal tern tracking data which has uncovered new details about their movements during breeding, migration, and overwintering. Of the 21 Royal Terns we’ve tracked to date, seven returned to the breeding colony in 2025 and nine returned in 2026.
Their migration routes varied quite a bit with some staying in the U.S. to winter in Florida and some going to the Dominican Republic, Cuba, Mexico, Panama, and Colombia.
“One new discovery we made this year was that four of our Royal Terns wintered in the same locations for two consecutive seasons,” said Goodenough. “This is an exciting finding and tells us just how important it is to conserve sites across the hemisphere for their continued use.”
New Findings
Thanks to the three years of data gathered from the backs of fast-moving Royal and Sandwich Terns, we’ve opened a world of new discoveries that will help us conserve these birds in North Carolina and beyond.
For the first time ever we’ve documented
- Royal Terns showing wintering site fidelity
- The migration route of a Sandwich Tern from the Atlantic Coast of the U.S. (North Carolina) to the Pacific Coast of South America (Peru)
“This research has underscored the importance of stopover and foraging areas for migrating waterbirds,” said Goodenough. “We only have them in North Carolina for about six months and spend the other part of their life in parts of the world that require international attention and collaboration.”
Audubon recognizes collaboration as a key aspect of our hemispheric approach to bird conservation. That’s why we work with partners like Dr. Goodenough, to help us understand the landscape our birds rely on and advocate for policies that allow them to thrive in every stage of life.
Audubon’s growing hemispheric reach and coordination with many partners at Conserva Aves is now working to protect habitat across the hemisphere, and maybe on both sides of these terns’ journeys.
Explore the migration maps below for more of our tracked birds.