Rare and Vagrant Migratory Birds Find Refuge at Corkscrew Swamp Sanctuary

Imagine you are a migratory songbird flying south for the winter. Your flight path, which may have started in the boreal forest of eastern Canada, takes you over mountains, valleys, farms, and urban areas. Sometimes you get to a location where land ends and water begins, such as South Florida, where you look for a place to stop, rest, and refuel before crossing the Gulf or Caribbean Sea.

For thousands of birds every year, Corkscrew Swamp Sanctuary is the perfect migratory resting place. A Ramsar-designated Wetland of International Importance and the regional gateway site for the Great Florida Birding and Wildlife Trail, Corkscrew Swamp Sanctuary is a key location on the Atlantic Flyway for migrating birds. Over the years, more than 268 bird species have been recorded here, including many rare and vagrant species, so it is no wonder the Sanctuary is also designated as an Audubon Important Bird Area.

The Canada Warbler

During migration, birds flock to the mosaic of habitats protected by the 13,000-acre Sanctuary. Sanctuary Director Keith Laakkonen was in the right place at the right time in September to spot a rare species, a Canada Warbler, foraging in the trees near the North Lettuce Lake.

Interestingly, most of the range maps for this bird do not show Florida at all. After their breeding season ends, most Canada Warblers travel west of the Appalachian Mountains to Mexico and avoid southeastern states altogether.

“There are always a few Canada Warblers that come down through Florida this time of year,” says Laakkonen. “The southeast coast of the Sunshine State gets more than we do here in southwest Florida,” he added.

According to Laakkonen, this was only the third Canada Warbler ever recorded on eBird at the Sanctuary, although at least seven have been documented in Collier County in recent decades. Because Collier County is larger than the state of Delaware, many more are likely passing through undetected. Some may be migrating across the Caribbean rather than following a land route. Researchers have identified three genetically distinct populations of Canada Warbler, and perhaps this could influence some migration routes.

Other Rare Visitors

Dozens of rare or “vagrant” birds have been reported at the Sanctuary in recent years. Just last year, staff and visitors reported an overwintering Wilson's Warbler, a Western Tanager, and a Lazuli Bunting, to name a few.

Bryant Dossman, PhD, director of the Audubon Everglades Research Station, says that vagrants are interesting in that they are rare occurrences by nature. “We find them in Florida sometimes because we are along their general trajectory,” he says.

How Birds Migrate

Songbirds use multiple cues to navigate, including proteins in their eyes that allow them to ‘see’ geomagnetic inclinations, as well as celestial cues for nighttime migration. Under all this, birds also have a genetic migratory program or ‘map’ that provides a general goal destination and route that can be honed by age and experience. But it’s not foolproof, and neither are their navigational abilities; so it is not unusual to expect that some birds will get lost.

Sometimes it is a random storm system, such as Hurricane Idalia in 2023, that blew hundreds of American Flamingos off course during their migration between Cuba and Mexico and deposited them in Florida and beyond. Many of those flamingos remain in the Sunshine State today.

Other times, it is a young bird migrating for the first time. “The first migration is always the most difficult since young birds are relying solely on their internal map and don’t have the luxury of experience to guide them, and so even small disturbances can lead them off course. And sometimes these internal maps can just be wrong when they haven’t experienced migration before,” Dossman adds.

What Becomes of These Individuals?

It is difficult to know for sure what happens to many of these birds. Some likely perish. According to Dossman, tracking is the only tool we have to understand where they end up.

“Sometimes a bird can get lucky, find good habitat, and survive winter to return north the following spring,” says Dossman. “Or it could be an early colonizer that returns the following year, potentially founding a population in a new area, which, over long enough timelines, is one way they end up becoming new subspecies,” he explains.

Migratory Bird Tracking

There is still so much to learn about migratory birds, and many scientists use tracking devices to study bird behavior. The  Motus Wildlife Tracking System  is an international, collaborative network run by  Birds Canada  that uses automated radio telemetry to track small flying animals, particularly birds, in real time. The Motus station installed at Corkscrew Swamp Sanctuary has detected 28 birds of 17 species since 2022.

The Bird Migration Explorer from Audubon's Migratory Bird Initiative and partners is an online initiative that combines data from Motus and many other sources. The result is a guide accessible to any bird enthusiast interested in learning about the heroic annual journeys made by more than 450 bird species and the challenges they face along the way.

For more than a century, Audubon has been working to secure and preserve the habitats birds rely on for their breeding, migration, and other essential needs. Birds tell us that they need places like Corkscrew Swamp Sanctuary every year, especially as migration brings a wide variety of birds this way. Human visitors also rely on the Sanctuary as a place to spend time in nature.