Pat and Doris Leary are avid birdwatchers and citizen scientists from Fernandina Beach, FL, who volunteer their time and substantial skills to survey coastal waterbirds in Northeast Florida, coastal Georgia and Florida’s Big Bend. This is the sixth blog in which they share their experiences and sightings as well as the challenges these increasingly imperiled birds face.
The term "snowbird" is familiar to Floridians and understood to represent northern residents who annually shift south to escape winter's harshest weather. But eons before humans adopted such behavior, countless generations of birds practiced a similar strategy flocking to Florida's shores or passing through to more favorable winter digs in lower latitudes as the sun made its seasonal descent in the northern skies. Human snowbirds are readily identified by out-of-state license plates, but their avian counterparts are more difficult to distinguish from resident birds unless they carry unique markers that identify their point of origin.
Fortunately, increasing numbers of birds carry markers in a broad variety of shapes and colors, making it possible to report the coded information and gain insight into each bird’s migratory pathways and longevity, knowledge that contributes significantly to long-term research and conservation efforts. Some birds are resighted and reported in multiple years because they spend every winter in Florida on the same beach area, a phenomenon known as "winter site fidelity". Transient migrants are less frequently recorded since they provide limited opportunity for detection during brief migratory stopovers in Florida.
On October 2, 2010, while Doris and I were conducting a routine regional survey, we noted several Caspian terns roosting among a flock of mixed species on Big Bird Island in lower Nassau Sound. One of the birds was banded with a large, light blue band engraved with the code (AEJ). Knowing the data was of value to the researchers who applied the markers, we reported the code to the Bird Banding Lab and later learned the bird had been banded as a young chick on Gull Island in Lake Ontario on 7/02/08. Since that time, we have recorded and reported other, uniquely-banded Caspian Terns but have yet to resight any of the same birds in the same area until this week.
On September 23, during a typical seasonal Nor'easter, I visited the jetty roost in Ft. Clinch State Park and found a large aggregation of mixed larid species hunkered on the shore sheltering from the gusty winds and light drizzle. Amongst the flock were less than ten Caspian Terns, including a bird with a light blue band engraved with the code (AEJ). As I photographed the bird, I wracked my memory and wondered if it might be the same tern resighted four years previously just south of Amelia Island. After processing the photos and checking our image archives I was pleased to discover that indeed, it was the same bird recorded and reported in 2010. Déjà vu!
Although Doris and I have recorded hundreds of uniquely marked birds of multiple species and some over many seasons and after thousands of miles of migration, this bird seemed special. We see relatively few Caspian terns in this region and most occur for a few weeks in early fall. Consequently, our opportunities to locate previously resighted terns are few, yet the annual journey of this bird crossed our pathway once again leaving us to marvel at the wonders of migration.