Although it is only March, our Science and Stewardship Department staff have been busy hiring and gearing up for the arrival of our seasonal ecology staff and the start of the 2023 field season. Although many of our vegetation-related projects do not get underway until plants begin to bloom and leaf out in late spring, our wildlife monitoring work often begins when it still feels like winter outside. One of the earliest projects that we initiate every year is shorebird monitoring, and – in past years – one of the first species to arrive on Nantucket to herald the beginning of the breeding season is the American oystercatcher (Haematopus palliates).
Although data is scarce, oystercatchers were likely common breeding birds all along the eastern U.S. coast prior 1900. However, their populations were severely impacted by over-hunting in the early 1900’s prior to protection under the federal Migratory Bird Treaty Act, passed in 1918. Their populations did not recover enough to reclaim coastal Massachusetts as part of their breeding range until 1969, when a pair was observed nesting on Martha’s Vineyard for the first time. Since then, their numbers have been increasing in this region, with a total of 51 pairs recorded nesting on Nantucket, Tuckernuck and Muskeget in 2022. On NCF properties, American oystercatcher nesting sites are found at Coatue, The Haulover, Eel Point, Pocomo, and Medouie Creek.
During the spring, summer, and fall, oystercatchers are now a common sight on Nantucket’s beaches, tidal flats, and salt marshes. This large, conspicuous shorebird has a long, bright orange bill, bright yellow eyes, and sharply-contrasting brown, black and white plumage. Its preferred prey is mollusks, marine worms, and shellfish obtained while feeding along the shoreline and tidal flats. Oystercatchers begin laying eggs in early April. They nest directly on the open beach or in patches of sandy habitat within salt marshes. Both parents incubate 1-3 eggs, which hatch after about 3 weeks. The chicks learn to fly within 4-5 weeks of hatching, and family groups usually remain together long after the breeding season has ended. Oystercatchers often linger on Nantucket until late fall or early winter – in fact, it is not unheard of for them to be sighted on Nantucket’s Christmas Bird Count in late December.
Anyone that spent the past four months on Nantucket will attest that it was (except for a few brutally cold days) a very mild winter. This has been the trend in the northeastern U.S. for some time and has been attributed to the many and complex effects of climate change. Research on the effects of these changing weather trends on bird migration is very much in its infancy. However, at a very local level, we may be observing recent signs of changing migration patterns for this species. A pair of oystercatchers was observed during the Tuckernuck Christmas Bird Count on December 28, 2022 and a single bird was observed on NCF’s Eel Point property on February 21, 2023- almost a month earlier than would be expected. Which leads us to wonder- Were these the same individuals? Did one or more oystercatchers overwinter on the island this past winter? Did these birds migrate and then return within a very short time frame? These particular birds were not banded, but continued research and monitoring may lead to answers to some of these interesting questions….
Since 2005, our Science and Stewardship Department has been one of many partners participating in the American Oystercatcher Working Group’s mission “to develop, support and implement range-wide research and management efforts that promote the conservation of Atlantic coast American Oystercatchers and their habitats.” This includes collaborating with researchers along the Atlantic coast on a coordinated, widespread effort to band and re-sight oystercatchers to learn about their complex patterns of movement and dispersal. There are currently active color-banding and/or re-sight projects underway all along the eastern seaboard from Massachusetts south to Florida and Texas. The color-bands used contain a unique 2-3 character code with a color combination specific to the state where the bird was banded (Massachusetts bands are yellow with black codes). Researchers are thus able to identify and track individual birds in the field without re-capturing them.
As a result of the hard work of many colleagues, a large percentage of Nantucket’s oystercatchers are now individually color banded: of the 25 pairs that nested on NCF’s beaches during the 2022 season, 15 adults and 18 chicks were banded. Oystercatchers can be extremely long-lived – it is not uncommon for birds to live at least 10 years, and there are records of banded individuals surviving up to age 17. Therefore, color banded individuals are often re-sighted for multiple years on both the breeding and wintering grounds. This data provides invaluable information about nest site fidelity (the tendency to return to the same breeding site), movement patterns between wintering and breeding ranges, and many other important population trends.
Breeding birds banded in Massachusetts have been re-sighted in Connecticut, New York, New Jersey, Maryland, Virginia. North Carolina, South Carolina, Georgia, the ocean and gulf coasts of Florida and Louisiana. Conversely, birds banded in New Jersey, Virginia, North Carolina, South Carolina, and Georgia have subsequently been observed here in Massachusetts. Interestingly, several birds that were recently banded as chicks on Nantucket were subsequently observed as far away as Mexico, Honduras and El Salvador – a previously undocumented migration pattern for this species prior to banding.
Our continued participation in this research will hopefully lead to more information on where our breeding oystercatchers are spending their time when they are not on Nantucket. If you are out and about on Nantucket’s beaches and observe a color-banded American oystercatcher, please call or email us with the code and the date, time and location where you saw it. This data can provide us and our research partners with extremely valuable information. Check out the American Oystercatcher Working Group’s excellent website page, which contains all kinds of information about this species, including a detailed explanation about how to identify banded birds. Additional data collected in the future will help us determine if the migration patterns of this species are shifting in the direction of oystercatcher sightings becoming more of a year-round occurrence here on Nantucket.
The Nantucket Conservation Foundation is a private, non-profit land trust that depends on contributions from our members to support our science projects, conservation property acquisitions and land management efforts. If you are not already a member, please join us now! www.nantucketconservation.org