Sharks of Onslow County
By late November, the New River of Onslow County—the slow, tidal estuary rising in Jacksonville and emptying into the Atlantic at New River Inlet—transforms. The grasses brown, the water clarifies, and the familiar pulse of summer predators fades. Flounder slip offshore. Red drum feed less frequently. Sharks leave the inlet behind in search of warmer currents.
But along the marsh edges, another group of predators steps forward.
Great egrets, snowy egrets, tricolored herons, great blue herons, kingfishers, cormorants, pelicans, and the few ospreys that overwinter become the defining hunters of the cold season. Their presence is not merely ornamental—they keep the estuary functioning when the fish and sharks of summer retreat.
This is a season to be thankful for the feathered predators who bridge water and land, carrying the New River through winter.
Mia McPhersonGreat blue (Ardea alba) and snowy egrets (Egretta thula) line the mudbanks of the New River like pale sentinels during late fall. Their precision hunting—patient standing, slow stepping, sudden striking—remains one of the most effective predatory strategies in shallow water. But egrets do much more than remove prey from the system.
Their feet stir the marsh. With every step, they oxygenate the upper sediment and dislodge hidden invertebrates—worms, amphipods, and tiny crabs. This stirring, known as bioturbation, is essential when larger predators leave for the season. It keeps nutrients moving upward through the food web instead of becoming locked in low-oxygen mud pockets (Green & Elmberg, 2014).
Egrets also function as indicator species. Their presence in good numbers along the New River—especially snowy egrets—signals healthy populations of juvenile fish and crustaceans, as these birds are sensitive to reductions in prey availability and water-quality decline (Gawlik, 2002).
In winter, when the big fish leave, the egrets’ quiet engineering keeps the marsh breathing.
Herons are the deliberate hunters of the New River’s cooler months. Great blue herons (Ardea herodias) stalk deeper edge-waters near Wilson Bay and Stones Bay, while tricolored and green herons hunt the narrow creeks and flooded grass near Sneads Ferry.
Their predatory pressure plays a critical stabilizing role.
When red drum, flounder, and juvenile sharks reduce feeding or migrate offshore, herons become the primary top-down regulators in shallow zones. Without them, schooling fish such as killifish and silversides can become overly abundant and overgraze algae mats, uproot detrital layers, and reduce habitat for invertebrates (Caldwell & Gawlik, 2020).
Herons prevent this imbalance, maintaining the delicate structure of marsh edges through the winter lull.
They are also highly sensitive to habitat degradation. If marsh edges are destroyed or water quality declines, herons disappear quickly—making them early warning signals of ecosystem stress.
When the estuary grows quiet, herons hold the line.
The New River bends—particularly between Jacksonville and Camp Lejeune—echo with the rattling call of the belted kingfisher (Megaceryle alcyon). These birds hunt where no heron can reach: suspended midair, diving into deeper channels for small mullet, anchovies, and menhaden.
Their role is uniquely important in winter.
Kingfishers distribute prey movement across the river. Their dive-bombing predation prevents baitfish from clustering into dense, oxygen-demanding schools. This reduces the chance of hypoxic pockets and helps keep prey species spreading through multiple river habitats, supporting overall food-web stability (Green & Elmberg, 2014).
As indicator species, kingfishers require:
A decline in their numbers often indicates erosion, turbidity, or human disturbance along the New River corridor.
When water clears and fish slow down, kingfishers regulate the mid-channel flow.
Where the marsh deepens toward New River Inlet, winter belongs to the divers.
Double-crested cormorants (Phalacrocorax auritus) gather in rafts, plunging beneath the surface in coordinated group hunts. Brown pelicans (Pelecanus accidentalis), though more numerous in summer, often overwinter near the inlet, diving from above for surface schooling fish.
These two species maintain control over mid-water prey populations during a time when bluefish, larger trout, and sharks are absent.
Cormorants keep cold-tolerant fish like anchovies and menhaden from becoming hyperabundant—preventing prey schools from stripping plankton layers or concentrating into stressed, oxygen-poor pockets. Pelicans, meanwhile, remove weak or diseased fish from the surface, helping maintain water quality and reducing pathogen spread (Green & Elmberg, 2014).
In winter, when predation usually thins, the divers take up the mantle offshore.
Most ospreys (Pandion haliaetus) migrate south, but a handful stay near New River Inlet and the Onslow County coastline each winter. Those that remain become the estuary’s apex aerial predators, taking mullet, juvenile trout, and medium-sized fish that no other bird consistently targets.
Their presence means something.
Ospreys are recognized worldwide as indicators of estuarine health, reflecting the state of fish recruitment, water clarity, and shoreline integrity (Green & Elmberg, 2014).
If ospreys disappear, it often signals a breakdown already underway.
Even in winter, they serve as a reminder of the estuary’s resilience—and vulnerability.
When fish-hunting birds decline, the system changes quickly:
Their disappearance is not cosmetic—it is structural.
These birds are the framework that holds the winter ecosystem together.
As fall deepens into the quiet months, the New River’s story becomes one of subtle but powerful relationships. Egrets stir the mud and release life into motion. Herons regulate the shallows. Kingfishers keep the channels moving. Cormorants and pelicans manage the deeper waters. Ospreys, if they stay, rule the sky.
They do not roar or thrash or leap.
They shape the estuary one step, one strike, and one dive at a time.
This Thanksgiving, the gratitude belongs to them as well—the birds who carry the New River through winter and keep the connection between land and sea alive.
Able, K. W., & Fodrie, F. J. (2015). Fish habitat use in salt marshes: Linking ecology and conservation. Marine Ecology Progress Series, 527, 1–5. https://doi.org/10.3354/meps11344
Caldwell, A. W., & Gawlik, D. E. (2020). Wading birds as top predators in shallow estuarine food webs: Behavioral influence on fish distribution. Estuaries and Coasts, 43(6), 1273–1286. https://doi.org/10.1007/s12237-020-00734-1
Gawlik, D. E. (2002). The effects of prey availability on the foraging behavior of wading birds. Ecological Monographs, 72(3), 329–346. https://doi.org/10.1890/0012-9615
Green, A. J., & Elmberg, J. (2014). Ecosystem services provided by waterbirds. Biological Reviews, 89(1), 105–122. https://doi.org/10.1111/brv.12045
Vance-Chalcraft, H. D., Duffey, R., & Knott, D. (2021). Linking avian and aquatic predators stabilizes estuarine food webs. Ecology, 102(12), e03540. https://doi.org/10.1002/ecy.3540
