Surveying for American Oystercatchers

by Sarah Tolve, Coastal Conservation Coordinator for Birds Georgia

Georgia Department of Natural Resources Biologist, Chris Depkin, operates the survey vessel after launching in the Barbour River at Harris Neck National Wildlife Refuge just after sunrise. Photo by Sarah Tolve/Birds Georgia.

The sun has yet to rise, but staff from the Georgia Department of Natural Resources and Birds Georgia are gearing up for the chance to shine a light on the wintering habits of one of Georgia’s state-listed species of concern — the American Oystercatcher (Haematopus palliatus). 

Launching from Harris Neck National Wildlife Refuge, GA DNR Biologists Tim Keyes and Chris Depkin were joined by Birds Georgia's Coastal Conservation Coordinator, Sarah Tolve, for a chilly day on the water. Tim hopes to survey the salt marsh and adjacent shell rakes (elevated oyster shell ridges along the marshside) for non-breeding American Oystercatchers and report banded birds back to their home states. 

Over the course of the winter, Tim’s team will survey Georgia’s entire 100-mile coastline for Oystercatchers. Sounds easy? Not when you consider that Georgia holds approximately 368,000 acres of salt marsh in those one hundred miles. On the Atlantic seaboard, Georgia is surpassed in acres of salt marsh only by South Carolina.

Nestled between the Ogeechee and Altamaha Rivers, the salt marshes of Liberty and McIntosh Counties support countless numbers of birds, fishes, invertebrates, and marine mammals. 

During the winter (non-breeding) season, as the tide approaches peak high tide, large groups of American Oystercatchers congregate on marsh islands, sandy beaches, and oyster rakes  -- making it slightly easier to observe large numbers of birds and survey for bands. As the tide recedes, birds begin to disperse to feed on intertidal mudflats and shellfish beds, and waterways become increasingly difficult to navigate (due to Georgia’s six to eight foot tidal fluctuation). 

---

A roosting flock near Saint Catherine’s Island. This flock numbered approximately 86 birds with about 10 sub-adult birds. We noted at least 12 bands in this group. Photo by Sarah Tolve/Birds Georgia.

---

In a typical winter, Georgia’s American Oystercatcher population numbers 900 to 1,100 individuals. During the breeding season, Georgia supports approximately 120 breeding pairs, mostly on undeveloped barrier islands and shell rakes.

Tim and team choose to survey two hours on either side of high tide to yield the best results. This gives a survey window of 4 hours -- enough time to cover a few known roosting sites. If conditions allow, and the birds are present, Tim surveys the group for bands using a spotting scope or a camera equipped with a long lens to prevent disturbance to the flock. 

After a quick scan and count of the flock, he estimates the ratio of subadults to adult birds in the group. Subadult birds will have a dusky brown tipped bill, while adults will be vivid orange with a faint yellow tip. Last, he looks for colored field-readable leg bands -- the color of the band corresponds to a certain state’s banding program. Florida and Georgia bands are red, South Carolina uses dark blue, North Carolina uses green, Virginia uses black, New York and New Jersey use orange, and Massachusetts and Connecticut use yellow. 

Whew! That’s a lot to remember. Good thing there’s a comprehensive resource for all things American Oystercatcher -- the American Oystercatcher Working Group (amoywg.org/.) We resighted red, yellow, green, black, and dark blue bands while on this survey.

---

Two subadult American Oystercatchers stand on a shell rake composed of oyster shells. Their bills are still tipped with brown, and their irises are not yet yellow. They have a black head, dark brown wings, and white chest. Photo by Sarah Tolve/Birds Georgia.

Why band birds?

Bird banding data is useful in both scientific research and management and conservation projects. Individual identification of birds makes possible studies of dispersal and migration, behavior and social structure, life-span and survival rate, reproductive success and population growth (USGS). By applying bands pre-fledging, an individual bird can be resighted over its lifetime without the need to capture it again. Typically made of metal or durable plastic, the bands are built to withstand the elements without being too cumbersome for the birds to carry over their lifetimes. 

Mark-resight (banding) studies coordinated by the American Oystercatcher Working Group have provided critical information, including linkages of breeding and wintering sites, rates of adult and juvenile survival, and relative importance of migration and wintering areas. These efforts are sustained through a long-term coordinated monitoring program (like Tim is leading here in Georgia) and help to inform management decisions and strategies. 

Although it has taken persistence and the commitment of many partners from Massachusetts to Texas, the North American population of American Oystercatchers has risen by approximately 50% -- an increase from roughly 10,971 birds in 2003 to roughly 14,735 in twenty years. (S. Shulte, Manomet, 2023) 

Predation of eggs and chicks, habitat loss or degradation due to sea level rise, and human disturbance continue to be major hurdles for oystercatchers population-wide. In a time when shorebird populations are on the decline globally, conservation successes such as this deserve praise.

---

An adult American Oystercatcher stands on a shell rake composed of oyster shells with Spartina alterniflora (Smooth Cordgrass) in the background. Its bill is solid, vibrant orange, and its iris is lemony-yellow. It has a black head, dark brown wings, pink legs, and white chest. It towers over the nearby Least Sandpipers. Photo by Sarah Tolve/Birds Georgia.

How Can I Help?
You don’t need to be a wildlife biologist to make a difference for Georgia’s birds.

If you live on the coast, you can join Manomet in advocating as a Shorebird Steward on one of Georgia’s barrier islands. From Tybee to Saint Simons to Cumberland, Shorebird Stewards station themselves along areas where both birds and people congregate. Their priorities include, but are not limited to efforts to reduce human and pet disturbance on beach nesting birds and to build awareness through education and outreach. Manomet’s Georgia Bight Shorebird Conservation Initiative hopes to inspire public appreciation and awareness of not only American Oystercatchers, but all shorebird and beach-nesting species we #ShareTheShore with. 

Visit the coast from time to time? While visiting Georgia’s (or any state’s) beaches, be mindful of the inhabitants and the journeys they endured to be sitting alongside you. Some, like the Red Knot, are simply stopping for a quick meal before continuing on their twice-yearly 9,000 mile migration.

• See a banded American Oystercatcher? Report it. Sightings can be reported at amoywg.org. You will even be given details about the bird's life history.
  • If you see a banded bird:
    • Note the date, time, & location — with GPS if possible
    • Note the species
    • Note which leg or legs have bands
    • Note the color and order of bands — upper or lower. If the band or flag has an alphanumeric code, try to note the code
    • Take a picture. Digital cameras work great through scopes or binoculars and sometimes enable eagle-eyed biologists to record numbers off of the band.
  • Note: Royal Terns, Piping Plovers, Red Knots, and Black Skimmers can also be equipped with field-readable bands. Each has a different reporting process. Visit reportband.gov for more information. 
• Respect and obey all posted areas and signage at the beach. The signs are there to help reduce disturbance to birds. When birds are disturbed from their nests, their eggs and chicks are exposed to danger from extreme temperatures and predators.
• Be attentive to birds. Even if you are outside a posting, if birds fly up or are agitated, you are too close. Move back and let them settle down.
• Obey all dog ordinances. When and where dogs are allowed on the beach, keep them on a leash and away from nesting areas and feeding or resting flocks. 
• Pack out all your trash, including food, and do not feed gulls. Leaving food waste behind attracts and subsidizes predator populations.

Three adult American Oystercatchers stand on one leg atop a shell rake ridge. Two of the three birds are banded. The left reads red[AMC] and the right dark blue[8X]. Photo by Sarah Tolve/Birds Georgia.

Coastal Connections - The Story of Red[AMC] and Blue[8X]

In the photo above stand three American Oystercatchers —  two with bands, one without. The bird on the left stands on one leg, with a red band coded [AMC]. This bird was banded by GA DNR Biologist, Tim Keyes, on Raccoon Key (near Ossabaw Island) on June 6, 2018. It has been seen seven times since, all in Georgia. It breeds on Saint Catherine’s Island Bar, where it was seen on November 30 during this survey.  

Conversely, the bird to the far right is banded with a dark blue band coded [8X]. This bird was banded in South Carolina in 2008 near Capers Island (north of Charleston) and has been resighted and reported just 10 times in the 15 years since. 

Since the third (middle) bird is unbanded, it is unknown where it hatched, where it breeds, and any other details of its life history. 

Thanks to information gathered by band-resight data, the lives of American Oystercatchers are beginning to be understood. An oystercatcher that was among the first banded in Georgia in 2001 was resighted in November 2022 by Sarah Tolve —  making that bird over 20 years old today. It is even still paired with a mate and maintaining territory on Cumberland Island. Every band resight and report helps further the knowledge base of imperiled species like American Oystercatchers. 

Although the salt marsh provides abundant food resources for the American Oystercatcher, it also provides the perfect perch for this Peregrine Falcon, who is known to prey on shorebirds. This bird's crop appeared very full and had likely just consumed a large meal. We also noted 4 adult Bald Eagles while on the survey route. Photo by Sarah Tolve/Birds Georgia.

---

Not only do American Oystercatchers enjoy roosting on the oyster shell rakes, American White Pelicans do as well! They have recently returned to the Georgia coast to winter, after spending the breeding season in California, Colorado, or Canada. Marshes are magnets for migrating birds and support birds from the smallest species, like Least Sandpiper, to the largest, like these White Pelicans and the Bald Eagle. Photo by Sarah Tolve/Birds Georgia.