The Silver Thread: Tracking Black Skimmers Reveals Vital Link Between Foraging Habits and Menhaden Abundance

This article was co-written with Brien Weiner of the South Shore Audubon Society, which serves the southern half of Nassau County on Long Island, New York.

The waters off Long Island’s Lido Beach are more than just a scenic backdrop for the community; they serve as a critical nursery and feeding ground for some of the Atlantic Coast’s most distinct avian residents. This summer, a team of researchers embarked on a sophisticated tracking project, fitting 20 Black Skimmers with GPS transmitters to better understand the daily movements of these birds. The primary objective was to map their foraging habits within the local back bays. However, the data returned by these transmitters painted a far more complex—and concerning—picture of environmental health and the struggle for survival in the face of fluctuating food supplies.

As the GPS data began to stream in, researchers were surprised by the extreme lengths to which these birds were traveling. While the nesting colony at Lido Beach remained their home base, the tracking devices revealed long-distance excursions spanning as much as 110 kilometers (68 miles). These were not casual flights; they were determined, high-stakes journeys reaching as far as New Jersey’s Gateway National Recreation Area. As the researchers pieced the tracking logs together, a singular, undeniable driver for this behavior emerged: the availability of Atlantic menhaden.

To understand the scope of these movements, researchers tracked the individual behaviors of specific birds within the colony. Among the most adventurous was an individual nicknamed "Michelle," a seven-year-old Black Skimmer that first hatched at the Lido Beach colony in 2019. While a significant portion of the tracked population restricted their movements to the immediate Long Island area, Michelle displayed a unique wanderlust. She became the only bird in the study to cross the Long Island Sound, embarking on repeated trips to Bridgeport and New Haven, Connecticut. Her foraging range was extensive, often extending east of the colony near Babylon and north toward the Bronx, demonstrating the sheer effort required when local food sources are insufficient.

Another tracked bird, "Ronald," offered a different perspective on the colony’s survival strategies. Ronald, an adult male, favored a different geographical trajectory. He frequently undertook nighttime excursions toward the Sandy Hook and Gateway National Recreation Area in New Jersey. Closer to his nesting grounds, he spent a significant amount of time in the marshes west of the colony, particularly in the vicinity of Bay Park. This area is currently the site of extensive infrastructure improvements, including a major upgrade to a wastewater treatment plant designed to improve the water quality and ecological health of the back bays.

The data provided a fascinating look at the demographic and temporal patterns of the colony. When analyzing the flight paths, researchers noted a clear behavioral split: males generally concentrated their foraging efforts to the west of the colony, while females showed a distinct preference for heading east. Perhaps most striking was the timing of these trips. Many of the most arduous, long-distance journeys occurred under the cover of darkness, between 10 p.m. and 3 a.m. This nocturnal activity suggested that the Black Skimmers were not merely choosing where to feed; they were being forced to travel remarkable distances, often in the dead of night, to secure the sustenance necessary for themselves and their chicks.

The impetus for this exhausting travel was hidden beneath the surface of the water. Atlantic menhaden, a small, silvery forage fish, are the linchpin of coastal ecosystems along the Atlantic. They serve as a critical food source for a vast array of marine life and avian predators. Data collected earlier in 2024 revealed just how essential these fish are to the Lido Beach colony, accounting for 41 percent of the diet of Black Skimmer chicks. However, during the early stages of the 2026 breeding season, menhaden were noticeably scarce in local waters, forcing the parents to look elsewhere.

The correlation between the fish and the birds was confirmed when the menhaden finally arrived in local waters between July 31 and August 8. Almost immediately upon the arrival of the schools of fish, the birds shifted their behavior. The long, exhausting flights across the Sound or to distant New Jersey marshes largely ceased, and the skimmers once again concentrated their foraging efforts in the back bays, much closer to their nesting grounds. This shift provided a clear, real-time illustration of how dependent the colony is on the local availability of this specific prey.

The consequences of the early-season scarcity were unfortunately measurable. While the Black Skimmer colony at Lido Beach typically maintains a productivity rate—a measure of successful fledglings—between 0.31 and 0.38, the 2026 season saw this figure dip to 0.25. Researchers believe the early lack of menhaden likely contributed to this decline, as parents were forced to expend more energy traveling further for food, leaving them with less time and resources to dedicate to chick-rearing.

The implications of this study extend well beyond the borders of Long Island. This November, the Atlantic States Marine Fisheries Commission, the regulatory body responsible for setting fishing limits for menhaden across New York and other coastal states, is scheduled to vote on an addendum that could significantly increase protections for the species over the next several years. Proponents of these protections argue that safeguarding the menhaden population is a vital step in ensuring the health of the entire Atlantic flyway. By ensuring that birds have reliable access to food along their migratory routes and during their breeding seasons, these policies would provide a buffer against the kind of scarcity that impacted the Lido Beach colony this year.

The benefits of such protections would be broad, extending far beyond the Black Skimmers. Atlantic menhaden are a fundamental component of the food web, and increasing their abundance would provide a necessary boost to other coastal predators, including osprey and bald eagles, both of which rely heavily on the health of these forage fish populations.

The summer tracking project was originally conceived as a way to identify the specific factors that make Lido Beach a successful nesting site compared to other locations along the Atlantic coast. By observing the movements of Michelle, Ronald, and the other 18 tagged birds, researchers have gained a deeper understanding of the ecological requirements of these coastal birds. Ultimately, the study revealed that the vitality of Long Island’s largest Black Skimmer colony is intrinsically linked to the presence of a small, silvery fish swimming hundreds of feet below their flight paths. As conservationists and policymakers look toward the future, the movements of these skimmers serve as a clear reminder that the health of our shorebirds is inextricably tied to the management of the marine resources beneath them.