Category: Behavioral Ecology

  • Where the Water Moves Before the Storm: Sharks, Estuaries, and the Illusion of Shelter in Onslow County

    Where the Water Moves Before the Storm: Sharks, Estuaries, and the Illusion of Shelter in Onslow County

    Where the Water Turns Before the Storm

    There’s a version of this story that shows up often—sometimes in films, sometimes in passing explanations—that when a large storm approaches, sharks move into estuaries to escape the violence of the open ocean.

    It makes intuitive sense.

    The ocean becomes something unmanageable—waves building, wind stacking energy across the surface. And just inland, the estuary appears contained. Narrower. Protected. A place where the water feels like it should be quieter.

    But if you stand at the edge of a tidal creek before a storm, what you see first isn’t protection.

    It’s change.

    The surface tightens. Wind presses across it—not yet breaking it into waves, but organizing it into long, directional movement. The irregular texture of a normal day disappears into something aligned. Purposeful.

    Water levels begin to rise before rainfall arrives. The boundary between water and marsh softens. Spartina no longer holds a sharp edge. The ground beneath your feet gives way more easily, saturated beyond its usual resistance.

    Water moving through a beach access during storm conditions, as rising levels and wind-driven flow begin to overtake the boundary between ocean and land. | Image credit: Jaime Armstrong
    Water moving through a beach access during storm conditions along the North Carolina coast, as rising levels and wind-driven flow begin to overtake the boundary between ocean and land. | Image credit: J. Armstrong

    This is the first shift.

    Not force, but redistribution.

    And everything in the system is already responding.

    What Lives Here When the System Starts Moving

    The sharks that use estuaries are not here because these places offer protection from storms.

    They are here because of what you can’t always see at first glance.

    A juvenile blacktip shark (Carcharhinus limbatus) doesn’t move through open water the way people imagine sharks do. It stays in the shallows—along the edges where the water darkens slightly, where small schools of fish break apart and reform, where the bottom shifts from sand to scattered shell. These areas are harder for larger predators to move through quickly. Not impossible—but slower, more complicated.

    Blacktip sharks move through estuaries in Onslow County, North Carolina, using shallow coastal water where movement, depth, and structure shape where they travel. | Image credit: kseym001. iNaturalist
    Blacktip sharks move through estuaries in Onslow County, North Carolina, using shallow water where depth, structure and movement shape where they travel. | Image credit: kseym001, iNaturalist

    That difference matters when you’re small.

    What scientists describe as “structure” is this: broken bottom, uneven depth, patches of grass, oyster shell, shadow, current seams. From the shoreline, it just looks like variation. To a young shark, it’s the difference between being exposed and being able to disappear for a second.

    That’s why these areas are used as nurseries—not because they are safe, but because they are less predictable in a way that favors smaller animals (Heupel et al., 2007).

    From a distance, it looks like open water. Up close, it’s a series of edges—grass, mud, and channels—where movement slows, shifts, and concentrates. | Image credit: A. Mitchell
    From a distance, it looks like open water. Up close, it’s a series of edges—grass, mud, and channels—where movement slows, shifts, and concentrates. | Image credit: A. Mitchell

    An Atlantic sharpnose shark (Rhizoprionodon terraenovae) uses that same space differently. You wouldn’t see it cruising the center of a channel. You’d find it where things intersect—along the drop where shallow water slips into deeper flow, near the edges of grass beds, or where current carries small prey out of the marsh and into open water.

    It’s not avoiding predators in the same way a juvenile blacktip is.

    It’s positioning itself where food moves, while still staying just out of the most exposed water (Ulrich et al., 2007).

    Even the bonnethead shark (Sphyrna tiburo)—often described as a “benthic feeder”—is easier to understand if you ignore the word and watch the behavior. It spends time over the bottom, moving slowly across seagrass beds and sandy patches, nosing through the substrate for crabs and small invertebrates.

    You’re most likely to notice it not by seeing the whole animal, but by the movement it leaves behind.

    A subtle disturbance. A shift in the grass. A shape that doesn’t hold still long enough to resolve.

    It’s also one of the few sharks you’re likely to find deeper into the estuary, where the water begins to lose its salt edge. Bonnetheads can tolerate lower salinity than many coastal sharks, which allows them to follow food farther into these mixed waters rather than staying closer to the inlet (Bethea et al., 2007).

    Not because it’s calmer there.

    Because the feeding opportunities extend into that space.

    These sharks are here because the estuary offers layers—places to feed, places to pass through, places where movement is broken up just enough to matter (Knip et al., 2010; Bangley et al., 2018).

    But all of those layers depend on something staying consistent—edges holding their shape, water moving in predictable directions, and clarity allowing animals to track one another.

    And those are the first things a storm begins to take apart.

    The Problem With “Shelter”

    When a hurricane approaches, an estuary does not become a refuge.

    It becomes harder to read.

    If you stand on the ocean side of Topsail Island, you’ll see the change first as energy—waves building, spacing tightening, the surface lifting and falling with more force than it did the day before. But if you cross to the other side of the island—along the Intracoastal Waterway or into Stump Sound—it doesn’t look like that.

    There, it rises.

    Steadily. Quietly. Without the same visible force.

    And that difference is exactly why the idea of “shelter” feels convincing.

    On the ocean side, the storm is easier to recognize. Energy builds into waves, making the movement visible in a way it isn’t on the other side of the island. | Image credit: WITN-TVFrom this side, it doesn’t look like a storm in the same way. The water rises and shifts along the shoreline, even as the system is already building offshore. | Image credit: A. Mitchell
    On the ocean side, the storm is easier to recognize. Energy builds into waves, making the movement visible in a way it isn’t on the other side of the island. | Image credit: WITN-TV. On the sound side, it doesn’t look like a storm in the same way. The water rises and shifts along the shoreline, even as the system is already building offshore. | Image credit: A. Mitchell

    Under normal conditions, these waters are connected—but they don’t move together. Ocean tides enter through New River Inlet and New Topsail Inlet, then work their way through the back-barrier system—the marshes, the Intracoastal, the sounds. That movement slows as it spreads out, which is why tides behind the island can lag the ocean by hours (Friedrichs & Aubrey, 1988).

    From the shoreline, it feels like separation.

    Like the ocean is doing one thing, and the water behind the island is doing another.

    As a storm approaches, that timing begins to compress. Wind pushes water through the inlets faster than the system can distribute it, while water already inside has less opportunity to drain back out.

    What was once staggered in time begins to overlap.

    Storm surge doesn’t just raise water levels—it disrupts the normal exchange between ocean and estuary, forcing water inland and holding it there longer than a typical tidal cycle (National Oceanic and Atmospheric Administration, 2023).

    That’s why the sound side doesn’t look violent at first.

    It’s not because it’s protected.

    It’s because it’s filling.

    You can watch it happen without measuring anything. The usual drop after high tide doesn’t come when you expect it. Water continues to rise or holds in place. The difference between ocean and sound begins to disappear—not because the ocean calms down, but because the back-barrier system begins to behave more like a single body of water under pressure.

    Edges blur as marsh grass floods from below. The bottom disappears as suspended sediment increases, and runoff and resuspension mix material into the water column faster than it can settle (Mallin et al., 1999).

    The system is no longer cycling. It’s shifting faster than it can recover, with the patterns that usually hold it together breaking down in real time (Resh et al., 1988).

    It’s accumulating.

    And once that happens, the things that made this environment usable begin to disappear with it.

    Where the Larger Sharks Actually Go

    If an estuary loses the very structure that makes it usable during a storm, then the question shifts.

    Sharks are not staying in place and enduring that change.

    They are moving with it.

    But not in the way we tend to imagine.

    They don’t need to move into something more protected, because the ocean itself isn’t uniform. What looks chaotic at the surface is layered, and that layering holds even as a storm passes overhead. Wave energy dissipates quickly with depth, which means that the violence you see from the beach does not extend indefinitely downward.

    A few meters below the surface, movement changes.

    Deeper still, it stabilizes.

    From above, the structure becomes visible—shallow bars, deeper channels, and the connections between ocean and estuary that shape how water moves through the system. | Image credit: Town of Topsail Beach
    From above, the structure becomes visible—shallow bars, deeper channels, and the connections between ocean and estuary that shape how water moves through the system. | Image credit: Town of Topsail Beach

    For larger coastal sharks like the bull shark (Carcharhinus leucas), that difference matters more than distance from shore. They are not choosing between rough ocean and calm estuary.

    They are moving within a three-dimensional space.

    And they sense the change before it arrives. It’s the same shift you feel before a storm—the air getting heavier, the pressure dropping, something changing before you can point to it. In the water, that change travels differently, and sharks begin responding to it well before anything looks different at the surface (Papastamatiou et al., 2015).

    From the shoreline, it can feel like the storm suddenly arrives. But for animals in the water, it doesn’t. The change builds, and they are already moving within it—shifting position, adjusting depth, following the parts of the system that are still holding together as everything else begins to change long before it’s visible from the shoreline (Heupel et al., 2003).

    Where the Shallow-Water Sharks Go

    The sharks that spend their time in these shallow systems don’t have the same options as those offshore, because there is no deeper layer to move into when conditions begin to change. Instead, their response is tied to what parts of the system still hold together. As water levels rise and flow patterns begin to shift, the backs of creeks and the shallowest flats are often the first places to lose definition. These are areas where water can become cut off or overly mixed, where direction is no longer consistent, and where the features that usually structure movement begin to disappear.

    What follows is not a movement further inland, but a gradual pulling back toward places that remain more stable. That often means deeper channels, intersections where water is still moving in a defined direction, or areas closer to inlets where exchange is still occurring. Rather than leaving the estuary entirely, many individuals consolidate within the portions of it that continue to function in a recognizable way. This kind of movement—shifting position as conditions change rather than holding in place—has been observed in coastal sharks as these systems begin to break down (Heupel et al., 2003).

    At the same time, the system itself is expanding beyond its usual boundaries. Storm surge and flooding connect environments that are typically separate, allowing water to move across marsh, into low-lying land, and through built spaces like roads, canals, and retention areas. When that happens, animals already present in the water column move with it, not because they are selecting those environments, but because the physical structure that normally contains them is temporarily absent. Observations of sharks and other marine species in flooded coastal areas are most often associated with these short-lived hydrological connections rather than deliberate movement into unfamiliar habitats (Snelson et al., 1984).

    As water spreads across the landscape, the system expands with it—connecting marsh, channels, and developed areas into a single, continuous space. | Image credit: C. Mitchell, AccuWeather
    As water spreads across the landscape, the system expands with it—connecting marsh, channels, and developed areas into a single, continuous space. | Image credit: C. Mitchell, AccuWeather

    As water recedes, those connections close just as quickly as they formed. The system contracts, and the pathways that briefly allowed movement into those spaces disappear. Animals either move back with the retreating water or are left in conditions that no longer support them. What appears from the outside as unusual behavior is, in most cases, the result of a system that has temporarily lost its boundaries and then reestablished them.

    Where the Assumption Breaks

    The idea that sharks move into estuaries for shelter during storms rests on a simple assumption: that calmer-looking water offers protection. From the shoreline, that assumption is easy to make. The ocean side of Topsail Island shows the storm first—waves building, energy increasing—while the waters behind the island, along the Intracoastal Waterway and within Stump Sound, often appear quieter in the early stages. But that difference is not a separation of systems. It is a difference in timing.

    Under normal conditions, tidal exchange through New River Inlet and New Topsail Inlet distributes ocean energy into the back-barrier environment with a delay, shaped by channel geometry and friction. That lag creates the appearance that one side of the island is responding differently than the other, when in reality both are part of the same connected system (Friedrichs & Aubrey, 1988). As storm conditions intensify, that delay compresses. Water is pushed through the inlets more rapidly than the system can accommodate, and the distinction between ocean and estuary begins to collapse into a single, continuous response driven by surge, wind, and pressure (NOAA, 2023).

    Sharks are responding to that shift the entire time, not by seeking out calm water, but by staying within parts of the system that hold their structure for as long as they can. Offshore, that structure exists vertically, allowing movement into deeper, more stable layers. Within estuaries, it exists horizontally and can disappear quickly as gradients break down. The concept of “shelter” depends on the persistence of those gradients—clear edges, directional flow, and predictable relationships between different parts of the system—but during a storm, those features are among the first to be altered.

    What remains after the storm is not evidence of animals moving into safer spaces, but the memory of contrast between what those spaces usually are and what they became under changing conditions. That contrast is compelling enough to shape interpretation, even when the underlying processes point to a different explanation.

    After the water recedes, the boundary remains shifted—marking where movement passed through, rather than where it began. | Image credit: J. Lester
    After the water recedes, the boundary remains shifted—marking where movement passed through, rather than where it began. | Image credit: J. Lester

    References

    Bangley, C. W., Paramore, L., Shiffman, D. S., & Rulifson, R. A. (2018). Increased abundance and nursery habitat use of the bull shark (Carcharhinus leucas) in response to a changing environment in a warm-temperate Estuary. Scientific Reports, 8(1). https://doi.org/10.1038/s41598-018-24510-z

    Bethea, D., Buckel, J., & Carlson, J. (2004). Foraging ecology of the early life stages of four sympatric shark species. Marine Ecology Progress Series, 268, 245-264. https://doi.org/10.3354/meps268245

    Ebert, D. A., Dando, M., & Fowler, S. (2021). Sharks of the world: A complete guide. Princeton University Press.

    Friedrichs, C. T., & Aubrey, D. G. (1988). Non-linear tidal distortion in shallow well-mixed estuaries: A synthesis. Estuarine, Coastal and Shelf Science, 27(5), 521-545. https://doi.org/10.1016/0272-7714(88)90082-0

    Heupel, M., Carlson, J., & Simpfendorfer, C. (2007). Shark nursery areas: Concepts, definition, characterization and assumptions. Marine Ecology Progress Series, 337, 287-297. https://doi.org/10.3354/meps337287

    Heupel, M. R., Simpfendorfer, C. A., & Hueter, R. E. (2003). Running before the storm: Blacktip sharks respond to falling barometric pressure associated with tropical storm Gabrielle. Journal of Fish Biology, 63(5), 1357-1363. https://doi.org/10.1046/j.1095-8649.2003.00250.x

    Knip, D., Heupel, M., & Simpfendorfer, C. (2010). Sharks in nearshore environments: Models, importance, and consequences. Marine Ecology Progress Series, 402, 1-11. https://doi.org/10.3354/meps08498

    Mallin, M. A., Posey, M. H., Shank, G. C., McIver, M. R., Ensign, S. H., & Alphin, T. D. (1999). Hurricane effects on water quality and benthos in the cape fear watershed: Natural and anthropogenic impacts. Ecological Applications, 9(1), 350. https://doi.org/10.2307/2641190

    NOAA. (2024, June 16). What is storm surge? National Ocean Service website. https://oceanservice.noaa.gov/facts/stormsurge-stormtide.html

    Papastamatiou, Y. P., Watanabe, Y. Y., Bradley, D., Dee, L. E., Weng, K., Lowe, C. G., & Caselle, J. E. (2015). Drivers of daily routines in an ectothermic marine predator: Hunt warm, rest warmer? PLOS ONE, 10(6), e0127807. https://doi.org/10.1371/journal.pone.0127807

    Pine, W. E., Pollock, K. H., Hightower, J. E., Kwak, T. J., & Rice, J. A. (2003). A review of tagging methods for estimating fish population size and components of mortality. Fisheries, 28(10), 10-23. https://doi.org/10.1577/1548-8446(2003)28[10:arotmf]2.0.co;2

    Resh, V. H., Brown, A. V., Covich, A. P., Gurtz, M. E., Li, H. W., Minshall, G. W., Reice, S. R., Sheldon, A. L., Wallace, J. B., & Wissmar, R. C. (1988). The Role of Disturbance in Stream Ecology. Journal of the North American Benthological Society; Freshwater Science, 7(4). https://doi.org/10.2307/1467300

    Ulrich, G. F., Jones, C. M., Driggers III, W. B., Drymon, J. M., Oakley, D., & Riley, C. (2007). Habitat Utilization, Relative Abundance, and Seasonality of Sharks in the Estuarine and Nearshore Waters of South Carolina. American Fisheries Society Symposium, 50, 125-139. https://lowcountryinstitute.org/images/research/dox/Ulrichetal2007.pdf

    Valiela, I., & Cole, M. L. (2002). Comparative evidence that salt marshes and mangroves may protect seagrass meadows from land-derived nitrogen loads. Ecosystems, 5(1), 92-102. https://doi.org/10.1007/s10021-001-0058-4

  • Dolphins of Onslow County Waters: Ecology and Shared Shoreline

    Dolphins of Onslow County Waters: Ecology and Shared Shoreline

    Dolphins of Onslow County: A Coastal Population

    There is often a moment before you see them.

    A breath breaks the air first — a soft exhale that sounds almost human — and then a dorsal fin lifts from the channel like a line drawn through moving water. The tide is falling. Gulls hover over the seam where current tightens. Fishermen pause mid-cast because everyone knows the rhythm: if the dolphins are working the edge, the fish are already gathering.

    These encounters feel spontaneous, but they are not accidents. The dolphins that surface beside our piers, marsh creeks, and inlets are not anonymous travelers passing through. Many bottlenose dolphins show long-term site fidelity and structured community patterns in estuarine systems, returning to the same places across years (Urian et al., 2009; Wells, 2014). To live on this shoreline is to share space with minds moving just below the surface — residents of the tidal edge.

    Who they are: a coastal population

    The dolphins most frequently seen along Onslow County’s waters are common bottlenose dolphins (Tursiops truncatus), a species whose “coastal” lives can look very different from “offshore” lives. Across the western North Atlantic, genetic studies show fine-scale population structure that can separate dolphins using nearshore coastal waters from dolphins using inshore estuarine waters (Rosel et al., 2009). More broadly, integrative work continues to support meaningful coastal vs offshore divergence in the region (Costa et al., 2022).

    In estuaries, photo-identification research (matching dorsal-fin markings) repeatedly shows that bottlenose dolphins can form discrete social communities with limited spatial overlap — a pattern consistent with long-term residency and local familiarity (Urian et al., 2009). In practical terms, the dolphin a child watches from a dock in spring may be seen again the following winter, and again the next year: not a rumor, but a biological possibility supported by long-term studies of resident dolphins elsewhere on the coast (Wells, 2014).

    Photo-identification doesn’t always rely solely on human matching of fin shapes; new tools such as machine learning are being developed to improve accuracy in identifying individual dolphins and whales in the wild. For example, researchers in Hawaii are using advanced algorithms to distinguish individuals from large photo libraries of dorsal fins. As technology improves, methods like photo-ID only get more reliable — which means studies of habitat overlap and seasonal return become more precise over time.

    An inside look at how scientists “read” dorsal fin shapes and markings to track the same dolphins over time.

    Reading the geometry of the estuary

    Dolphins do not simply occupy estuaries; they interpret them.

    Tidal channels function as moving architecture. Falling tides compress fish schools toward narrowing exits. Sandbars redirect flow into faster seams. Marsh edges trap prey against shallow gradients. Dolphins exploit these features with precision, repeatedly targeting conditions that make prey capture more efficient (Barros & Wells, 1998; Torres & Read, 2009).

    This is one reason dolphins so often appear where the water “looks alive” — at convergence lines, inlet throats, and channel bends. In Florida Bay, for example, foraging tactics are mapped onto habitat features that define where dolphins have spent their time, thus turning behavior into geography (Torres & Read, 2009). What seems like play from shore can be highly strategic predation.

    Bottlenose dolphins breaching off Seaview Pier, N. Topsail Beach, North Carolina. The arc of the body and column spray reflect the mechanics of propulsion - force directed through the tail, momentum carried into the air. | Photo credit: Howard Crumpler Photography, 2026
    Bottlenose dolphins breaching off Seaview Pier, N. Topsail Beach, North Carolina. The arc of the body and column spray reflect the mechanics of propulsion – force directed through the tail, momentum carried into the air. | Photo credit: Howard Crumpler Photography, 2026

    Reader Question:

    Why do dolphins seem more active on rainy or overcast days?

    Weather, light, and the illusion of play

    You may notice that dolphins seem especially active on overcast or rainy days — surfacing more frequently, breaching, or moving in tight arcs through wind-rippled water. It can look like preference, even mood. But dolphins are responding less to cloud cover than to what cloud cover does to the water.

    When the sky darkens, baitfish don’t stay arranged the same way. They may bunch together or rise toward the surface. For a predator already working those upper layers, that shift can make hunting more efficient (Benoit-Bird & Au, 2003). Wind and rain can also stir the surface and cloud the water, changing who sees whom first (De Robertis et al., 2003).

    There is also a perceptual component. Overcast skies reduce glare, making dorsal fins and splashes easier for human observers to detect. Wind-textured water highlights movement. What appears to be “more play” may sometimes be improved visibility — a reminder that observer experience and animal behavior are not always the same phenomenon.

    In short, dolphins are responding to ecological conditions. The weather alters the water; the water alters the fish.

    Two bottlenose dolphins break the surface beneath the gray horizon off Surf City, North Carolina. Overcast light and wind-roughened water can change how fish move – and how easily we notice the dolphins following them. | Photo credit: Johnny Provost, Jr., 2025
    Two bottlenose dolphins break the surface beneath the gray horizon off Surf City, North Carolina. Overcast light and wind-roughened water can change how fish move – and how easily we notice the dolphins following them. | Photo credit: Johnny Provost, Jr., 2025

    Communication and social intelligence

    Bottlenose dolphins have been studied for decades not just because they are charismatic, but because their social lives depend on constant communication in a shifting, three-dimensional world. One of the strongest findings to emerge from that research is the existence of signature whistles — individually distinctive call types that function as learned identity signals, something very much like the individual name a dolphin goes by within its community (Janik & Sayigh, 2013).

    Social learning runs just as deep. Some dolphin foraging habits spread from one animal to another rather than through genetics — passed along socially, a rare pattern among nonhuman species (Krützen et al., 2005). Mothers and calves stay together for years, giving calves time to learn not just how to hunt, but where — which channels to follow, which bends of water hold fish (Wells, 2014).

    In some populations elsewhere in the world, dolphins even use tools — carrying marine sponges on their rostrums while foraging or trapping fish inside empty shells — behaviors that are socially learned and culturally transmitted (Krützen et al., 2005).

    That learning shapes how dolphins fit into the estuary. In many tidal systems they sit near the top of the local food web, influencing the fish communities beneath them. Yet beyond those protected waters, they are not beyond risk. Large sharks prey on dolphins, placing them within a broader coastal hierarchy where even predators can become prey (Heithaus, 2001). The role shifts with scale. The ecology remains layered.

    Two bottlenose dolphins surfacing together off Seaview Pier, N. Topsail Beach, North Carolina. Close positioning and timing are hallmarks of the complex social bonds that define dolphin societies. | Photo credit: Howard Crumpler Photography, 2026
    Two bottlenose dolphins surfacing together off Seaview Pier, N. Topsail Beach, North Carolina. Close positioning and timing are hallmarks of the complex social bonds that define dolphin societies. | Photo credit: Howard Crumpler Photography, 2026

    Dolphins are not guardians

    Popular culture has assigned dolphins a role they never chose: protector. People repeat a comforting shoreline myth — “If you’re scared of sharks, find the dolphins; they’ll protect you.” But that story is not grounded in how dolphins behave in the wild.

    Bottlenose dolphins are powerful predators. They compete, establish dominance hierarchies, and can deliver forceful blows when defending calves or asserting space. Dolphin–shark interactions occur, but they are not “rescue missions” staged for humans; they are ecological encounters shaped by risk, competition, and opportunity (Heithaus, 2001).

    Wild dolphins are also capable of injuring people. Research examining human–dolphin interactions show that close approaches — and especially feeding wild dolphins — increase the likelihood of risky contact and harmful outcomes for both dolphins and people (Cunningham-Smith et al., 2006; Vail, 2016). Over time, those interactions leave visible consequences. Long-term data from Sarasota Bay show that dolphins who have learned to associate people with food are more likely to carry injuries linked to boats and fishing gear (Christiansen et al., 2016).

    The danger is not that dolphins are “evil.” The danger is assuming they share human intentions.

    Swimming near a pod does not create a protective shield. Dolphins are not lifeguards. They are wild animals navigating their own priorities in a shared environment. Respecting that boundary is what allows coexistence.

    A bottlenose dolphin pursuing prey near a recreational vessel in a waterway in Surf City, North Carolina. Foraging behavior can bring dolphins into close proximity with boats – not as companions, but as active predators focused on fish. | Video credit: Cynthia Dirosse, 2024

    Winter dolphins

    A persistent assumption is that dolphins vanish when the water cools. In reality, seasonal distribution can be more nuanced — changing with prey, temperature, and coastal movement patterns rather than following a simple on/off presence.

    Along the mid-Atlantic coast, research shows that bottlenose dolphins shift their movements with the seasons, appearing in different areas at different times of year (Torres et al., 2005). Studies focused on estuarine dolphins in southern North Carolina document similar seasonal patterns closer to home (Silva et al., 2020). From shore, those changes can look like disappearance. But winter quiet does not always mean absence. It may simply mean dolphins are working deeper channels or less visible pathways beyond the easy reach of our eyes.

    The estuary in winter is quieter, but not empty.

    Dorsal fins in winter light off Surf City, North Carolina. Dolphins may appear less active this time of year, but changes in light, water depth, and travel corridors often influence what we notice from shore. | Photo credit: Surf City Parks, Recreation, and Tourism, 2017
    Dorsal fins in winter light off Surf City, North Carolina. Dolphins may appear less active this time of year, but changes in light, water depth, and travel corridors often influence what we notice from shore. | Photo credit: Surf City Parks, Recreation, and Tourism, 2017

    Living beside them

    Living near dolphins is a privilege — and it places us within the same waters they navigate. Vessel traffic, fishing gear, and repeated close approaches can shape the lives of animals that live for decades and raise calves slowly (Wells, 2014). Studies of dolphins that have been fed or closely approached by people show that these interactions can shift behavior, making dolphins more likely to approach boats and increasing the risk of injury and conflict (Vail, 2016). Distance, in that sense, preserves the patterns people come to watch.

    The presence of dolphins is not guaranteed. It is a sign that the system still functions — prey, water quality, shoreline structure, and the complex social knowledge dolphins carry from year to year. As long-lived predators near the top of the food web, they are indicator species, reflecting the condition of the waters they inhabit — estuary, inlet, and nearshore coast alike.

    And so when a dorsal fin rises beyond the channel markers, it means more than a moment of spectacle. It means the currents are still working, the fish are still moving, and the layered relationships that shape this shoreline are still holding.

    There is always more to learn about dolphins than fits in a single post. For those who’d like to go further, this episode of the All Creatures Podcast offers a thoughtful exploration of their biology and behavior.

    References

    Barros, N. B., Wells, R. S., & Barros, N. B. (1998). Prey and feeding patterns of resident bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida. Journal of Mammalogy, 79(3), 1045. https://doi.org/10.2307/1383114

    Benoit-Bird, K. J., & Au, W. W. (2003). Prey dynamics affect foraging by a pelagic predator (Stenella longirostris) over a range of spatial and temporal scales. Behavioral Ecology and Sociobiology, 53(6), 364-373. https://doi.org/10.1007/s00265-003-0585-4

    Christiansen, F., McHugh, K. A., Bejder, L., Siegal, E. M., Lusseau, D., McCabe, E. B., Lovewell, G., & Wells, R. S. (2016). Food provisioning increases the risk of injury in a long-lived marine top predator. Royal Society Open Science, 3(12), 160560. https://doi.org/10.1098/rsos.160560

    Costa, A. P., Mcfee, W., Wilcox, L. A., Archer, F. I., & Rosel, P. E. (2022). The common bottlenose dolphin (Tursiops truncatus) ecotypes of the western North Atlantic revisited: An integrative taxonomic investigation supports the presence of distinct species. Zoological Journal of the Linnean Society, 196(4), 1608-1636. https://doi.org/10.1093/zoolinnean/zlac025

    Cunningham-Smith, P., Colbert, D. E., Wells, R. S., & Speakman, T. (2006). Evaluation of human interactions with a provisioned wild bottlenose dolphin (<I>Tursiops truncatus</I>) near Sarasota Bay, Florida, and efforts to curtail the interactions. Aquatic Mammals, 32(3), 346-356. https://doi.org/10.1578/am.32.3.2006.346

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