Banding Offers a Clue into the Mysterious World of Birds

On a hot, windy beach last year in Pinellas County, Florida, two Black Skimmers found each other after spending a winter apart. Striking black-and-white birds with orange and black bills, the species is named for the way they skim their prey from the surface of the water.

Digging a scoop nest in the dune sand, this particular pair laid eggs and, later in the summer, fledged a handful of fluffy chicks. Nearby, Audubon Florida staff and volunteers celebrated, as the skimmer duo had been trying to nest together for three years in a row. How do we know?

Bird banding.

Audubon Florida’s banding program began in 2009, when staff carefully weighed and measured Least Tern chicks nesting on rooftops in Pinellas County.

Least Terns are small seabirds that nest throughout much of the continental United States during the summer months before migrating south for the winter. While historically they have nested in mixed-species colonies directly on sand, human development, disturbance, and increased predation have sent many to gravel rooftops, which resemble their preferred habitat while protecting their chicks from on-the-ground dangers. Audubon staff both monitor the rooftop colonies and install fencing to prevent as many chicks from falling off the roof as possible.

However, since banding began, we have learned that these baby birds are surprisingly resilient—the majority of chicks that fall off of their rooftop nesting sites actually survive to fledge. Moreover, baby terns born in these rooftop colonies can go on to nest on beaches or roofs, and do not necessarily choose to nest on the sites where they were born. In fact, once a colony breaks up, birds disperse to different beaches and wintering grounds.

Critical information on rooftop Least Terns has taught researchers that these colonies not only produce fledglings for future roof nesting, but also join colonies up and down the Florida coastline. Put simply, protecting the roofs protects an important breeding pool that can pump up beach-nesting colonies as well.

Building on the Least Tern research, Audubon Florida - in partnership with Dr. Beth Forys of Eckerd College - began to band Black Skimmer chicks in 2015 in an ongoing effort to unravel the mysteries of their annual movements.

Audubon coastal biologists protect and steward state-threatened Black Skimmer colonies nesting on urban Pinellas County beaches each year. Until recently, little information was known about the age, birthplace, and winter whereabouts of the nesting skimmers at these sites.  Additionally, in 2017, Audubon’s staff began banding skimmer chicks on Marco Island. With all the sighting records of banded birds since 2015, we know a lot more about the birds’ movements, population dynamics, and habitat, including the fate of repeat nesters.

Audubon joins organizations from across the United States to report banded birds and share monitoring information. Last fall, during the fading light of sunset on Key West, one of Audubon’s dedicated community scientists reported two banded skimmers. After looking through records, Marianne Korosy, Ph.D., Director of Bird Conservation for Audubon Florida, discovered that the first was born and tagged less than a year earlier on Indian Rocks Beach, 230 miles up the Florida coast, and the second was banded in 2017, traveling all the way from New York!

“Black Skimmer nesting sites are vulnerable to storms, sea level rise, and human disturbance,” says Korosy. “The more we know about their movements, the better we can protect them into the future.”

Audubon is working across the Gulf Coast to fill in the gaps in our knowledge of our coastal bird populations. Ten years ago, when the BP Deepwater Horizon oil disaster began, we learned that this knowledge is critical, not only to determine how many birds were lost during that time, but also to monitor the recovery of our coastal bird populations. To learn more about Audubon’s vision to restore the Gulf for birds and people, check our Gulf plan.

Have you seen a banded bird? Learn how to report your sighting here!

Portions of this blog were previously published on Audubon Florida’s website by Renee Wilson.