Oystercatchers Need Our Help: Wetlands Institute Studying Delaware Bay Populace in Conservation Effort
American oystercatchers in winter at Stone Harbor Point.
It might come as no surprise that the Delaware Bay, long known for its oysters, also supports a population of American oystercatchers, but we are just beginning to gain a full understanding of these birds on the bay.
You might be familiar with this large, charismatic shorebird from the Atlantic Coast beaches, where it draws attention with its flashy appearance, boisterous vocalizations, and entertaining behaviors. As the name implies, oystercatchers do feast on oysters, but their specialized bills can open any type of marine bivalve, including mussels and clams.
Because of their marine diet, oystercatchers are restricted to coastal habitats, and in New Jersey they can be found in both salt marshes and on sandy beaches. Oystercatchers, like other beach-nesting birds, lay their eggs directly on the sand in a small indentation they dig out, called a scrape. The eggs and chicks are camouflaged to blend with the sand, but they are still vulnerable with only their parents to fend off danger.
Oystercatchers face many threats, including habitat loss from coastal development, recreational disturbance, predation, and increased flooding from climate change and sea-level rise. In addition, their nesting season coincides with peak activity for people in the coastal areas where oystercatchers nest. These threats have significantly reduced the available habitat and the breeding success of these and other beach-nesting birds. Because they are sensitive to changes in coastal resources, oystercatchers are indicators of the overall health of the coastal ecosystem, and they serve as a flagship species for other species of high conservation concern that share the same habitat and threats.
In 2000, research showed that their entire North American population – from Massachusetts to Florida and along the Gulf Coast – consisted of only about 10,000 birds. This led to a surge in research focused on efforts to recover the population. Oystercatchers can live for a long time but have low reproductive rates, making it difficult to recover quickly from a population decline. For 20 years, the oystercatcher population that breeds along New Jersey’s Atlantic Coast beaches has been monitored, managed, and protected, resulting in a slow but steady population increase. However, little attention was paid to the birds that breed along the state’s Delaware Bay beaches.
Now, thanks to funding from the National Fish and Wildlife Foundation, a collaborative effort – led by Conserve Wildlife Foundation of New Jersey and joined by the U.S. Fish and Wildlife Service and The Wetlands Institute – is giving this small population the attention it deserves.
This spring, we located and closely monitored breeding pairs to begin filling the data gaps that can inform conservation plans. The team used fencing and signage around nesting areas exposed to human disturbance to help the birds nest successfully, and collected information about where they nested and the types of areas they favored. This information can be important in future habitat restoration projects.
One of The Wetlands Institute’s contributions to the project is to band oystercatchers. Our trained and permitted staff safely fit adult and juvenile birds with a uniquely coded orange band on each leg, which can be read in the field with a spotting scope. Anyone who observes a banded bird can report the code to a central database, which helps researchers track the bird’s movements. Tracking banded birds can be useful for studying where the birds are feeding, spending the winter, and even where they make migration stopovers.
The first adult oystercatcher was banded on Moores Beach in 2018, and until this year was the only banded oystercatcher in the Delaware Bay region. This bird – with a band code of A76 and affectionately named “Evermoore” – has nested at this site in Delmont every year since she was banded. This year we were also able to band her mate, and can now determine if this pair continues to stay together. (It is not uncommon for oystercatchers to remain with the same mate for life.)
Something else we learned from Evermoore is that when the breeding season is over, she spends up to three months with a large flock of oystercatchers at Stone Harbor Point. During the breeding season (March-July), oystercatchers are highly territorial. From courtship through the fledging of young, pairs defend their territories in noisy and sometimes aggressive displays. Once breeding is complete, however, they gather with other oystercatchers in large roosting flocks throughout fall and winter. Some of the birds eventually move on from this fall “staging” area to a wintering location further south. Others stay in New Jersey to overwinter, and Stone Harbor Point is one of the few wintering locations in the state.
This year we have already seen other banded oystercatchers from the Delaware Bay – both adults and juveniles that were hatched this year (including Evermoore’s offspring, Schooner, band code C40) – spending time in the staging flock at Stone Harbor Point. This clearly demonstrates a connection between the habitat in the Delaware Bay region and the habitat on this Atlantic Coast barrier island. During their time in New Jersey, these birds are using at least two important sites, and each site is important to them for different reasons. Time will tell if these birds will stay for the winter or migrate to a warmer climate. We hope to get reports of some of our Delaware Bay birds from other states over the winter so we can discover where they spend the cold months.
Oystercatchers don’t reach breeding age until they are 3 to 4 years old. Immature birds often hang out in flocks during this stage, and don’t choose their nest sites until they are ready to pair up and start breeding. This year, oystercatcher J08 – banded on Long Beach Island as a chick in 2019 – nested for the first time in our study area near Moores Beach. It was interesting that this bird that was hatched on a barrier island on the Atlantic Coast chose to breed in the very different landscape of the Delaware Bay.
We are looking forward to a second season of learning more about the Delaware Bay oystercatchers and adding more banded birds to our study. Our goal is to band at least one adult of each breeding pair, in addition to as many chicks as possible. It will be several years before we find out where these chicks decide to settle down and whether they will stick close to their origins in the Delaware Bay or explore a different part of New Jersey – or even a different state. If you see a banded oystercatcher and can read the code, please report it to the American Oystercatcher Working Group at amoywg.org. Reporting bands assists with the research and conservation of these beautiful birds that need our help.