When you see a large group of gulls wheeling in circles overhead, the most common explanation is that they have found food or are about to. Gulls are intensely social foragers, and a swirling mass of birds functions as a kind of living billboard advertising a meal below. But food is not the only reason. Gulls also circle to exploit columns of rising warm air called thermals, gaining altitude without flapping and saving considerable energy. Sometimes it is both at once, and sometimes it is neither. The behavior is more readable than it looks once you know what cues to watch for.
The Dinner Bell Effect
Gulls rely heavily on each other when searching for food. Researchers who study seabird foraging describe this as “local enhancement,” a process where the sight of other birds feeding draws more individuals to the same spot. A single gull diving toward the water or swooping toward a dumpster can trigger a rapid chain reaction, pulling in birds from surprisingly far away. Because gulls are colonial breeders that spend their youth watching adults forage, they get years of practice reading the body language and flight patterns of other gulls before they ever have to find food on their own.1Biological Reviews. Social interactions and information use by foraging seabirds
The circling you see is often the arrival phase of this process. When the first few birds locate something worth eating, they start orbiting the site, calling as they go. Those calls and the visual spectacle of birds banking and wheeling draw in more gulls from surrounding areas. The newcomers circle too, partly to assess the situation and partly because there may not be room to land yet. Within minutes a handful of birds can become dozens or hundreds. If the food source is large and sustained, like a fishing trawler hauling in nets or a freshly opened landfill cell, the flock can grow enormous and persist for hours.
This social-information network is not limited to members of the same species. Herring gulls, black-backed gulls, ring-billed gulls, and various terns will all respond to each other’s feeding frenzies. A mixed-species spiral of birds almost always means a concentrated food source below, because different species would not all converge on the same point by coincidence.
Thermals and Energy-Saving Flight
Not every gull circle is about food. Gulls are skilled soaring birds, and they regularly exploit thermals, which are columns of warm air rising from sun-heated surfaces. By spiraling inside a thermal, a gull can gain hundreds of meters of altitude with almost no wing-flapping, then glide long distances to its destination. This is the same trick that hawks and vultures use over open country, but gulls have adapted it to human landscapes. Research tracking lesser black-backed gulls with high-resolution GPS found that these birds routinely use thermal soaring even in cool, damp climates where you might not expect strong thermals to form.2PubMed. Built up areas in a wet landscape are stepping stones for soaring flight in a seabird
Towns and cities are particularly good thermal generators. Concrete, asphalt, and rooftops absorb solar energy and radiate heat, creating reliable pockets of uplift. The same GPS tracking study showed that gulls preferentially route their flights through built-up areas to catch these urban thermals, essentially using towns as stepping stones for energy-free travel. So if you see a group of gulls circling high above a parking lot or a commercial district on a warm afternoon, they may simply be hitchhiking on rising air before gliding off somewhere else. The telltale sign is altitude: thermal-soaring gulls tend to spiral upward steadily and then peel away in a long glide, whereas food-motivated gulls circle lower and descend toward the ground.
How to Tell Food Circling from Thermal Soaring
Distinguishing the two behaviors is easier than you might think if you watch for a few minutes. When gulls are working a thermal, the flock usually drifts with the wind, the birds gain altitude in a fairly tight corkscrew, and the circle eventually breaks apart as individuals glide off in different directions. There is relatively little calling, and the birds hold their wings in a steady soaring posture without much flapping.
Food circling looks different. The flock tends to stay anchored over one location. Birds drop out of the circle to dive or land, then rejoin. The calling is loud and continuous, especially the classic “laughing” and “keow” calls that signal excitement and competition. You will often see birds chasing each other or attempting to steal food from a neighbor’s bill. The circle may tighten and loosen as waves of new arrivals pile in.
There is a hybrid situation that can fool you. On warm days over a landfill or fishing harbor, the heat rising from the site and the food below produce both thermals and a feeding frenzy simultaneously. Gulls at the top of the spiral may be soaring on the updraft while birds at the bottom are actively feeding. The whole column looks like one behavior but is actually two layered on top of each other.
Urban Gulls and Human Schedules
If you live in a city and notice circling gulls at oddly predictable times, you are not imagining things. Urban gulls have learned to synchronize their foraging with human routines. GPS-tracked lesser black-backed gulls in Bristol, for example, shifted their visits to schoolyards, parks, and waste facilities to match the times when food was most available at each site. On weekdays the birds concentrated at schools during lunch periods and at waste centers during operating hours. On weekends, visits to those same locations dropped sharply because there was less human-generated food to exploit.3PubMed Central. Urban gulls adapt foraging schedule to human-activity patterns
This level of schedule-tracking means that gulls circling over a school at noon are probably responding to the burst of food scraps that appears when children eat outdoors. Gulls circling over a restaurant district in the evening are reading the pattern of outdoor diners and overflowing bins. It is not telepathy; gulls simply learn from repeated experience which places produce food at which times, and they show up accordingly. If a flock starts circling your neighborhood at the same time every day, think about what human activity might be generating food waste on that schedule: trash collection, outdoor dining, a food truck, even a factory that dumps organic waste at a set hour.
Landfills and Waste Sites
Few things attract circling gulls as reliably as an active landfill. When a new cell is opened or fresh waste is deposited, the exposed organic material is an enormous, easy food source. Gulls arrive in large numbers and can be seen spiraling above the site from considerable distance. Research on bird activity around landfills near airports has shown that gulls are drawn to these sites around the clock, including at dawn and even at night when garbage from overnight dumping remains exposed.4Journal of Toxicology and Environmental Health, Part A. Landfills, nocturnal foraging, and risk to aircraft
The aviation connection is worth mentioning because it shapes how seriously some communities take gull aggregations. Bird strikes are a real hazard for aircraft, and gulls are among the species most frequently involved. Airports near landfills face elevated strike risk, especially in early fall when inexperienced young gulls are still learning where and how to forage. If you notice large circling flocks near an airport, it often indicates that a waste facility or other major food attractant is operating nearby, and aviation authorities are usually well aware of the problem.
Fishing Activity and Offshore Circling
If you are near the coast, a dense whirlwind of gulls over the water almost always marks a concentration of fish near the surface. Sometimes the fish have been driven upward by predators below, like mackerel or tuna pushing baitfish into a tight ball. Sometimes a commercial fishing boat is hauling nets or processing catch and dumping bycatch overboard. Either way, the gulls are exploiting a brief, intense burst of accessible food, and the circling pattern serves to recruit even more birds from the surrounding area.
Interestingly, gulls do not just passively wait for food to appear. Herring gulls have been documented adjusting their behavior in real time based on how productive a food source is. Near puffin colonies, for instance, herring gulls increase their rate of kleptoparasitic attacks (stealing food from returning puffins) on days when more puffins are carrying fish back to their nests.5Canadian Journal of Zoology. Behavioural responses of Common Puffins to kleptoparasitism by Herring Gulls The gulls are essentially reading the productivity of another species and calibrating their own effort. This kind of flexible, information-driven foraging is part of why gulls are so successful in such a wide range of habitats.
Storms, Weather, and the Folklore Connection
There is a long-standing folk belief that seagulls circling inland means a storm is approaching. Like a lot of weather folklore, this one has a kernel of truth wrapped in a lot of overstatement. When a storm front moves in over the ocean, conditions at sea become dangerous for smaller seabirds. Strong winds, heavy rain, and reduced visibility make it harder to forage, and waves may scatter the surface fish that gulls depend on. Some gulls will move inland ahead of rough weather, and if they concentrate over fields, parking lots, or other open areas, they may circle while looking for alternative food or waiting for conditions to improve.
But this is far from a reliable weather forecasting tool. Urban gulls already live inland year-round and circle for all the reasons described above without any storm in sight. Coastal gulls may move inland for reasons that have nothing to do with weather: a nearby landfill opened, a farmer is plowing a field and turning up invertebrates, or the local fish simply are not biting. If you see gulls circling unusually far from the coast and the sky is darkening, a storm may well be coming. But gulls circling in a city on a clear Tuesday afternoon are not predicting anything except lunch.
Roosting and Pre-Sleep Gatherings
Not all gull aggregations involve food or thermals. In the late afternoon and evening, gulls often gather in large numbers at communal roosting sites, typically on open water, flat rooftops, or large fields. Before settling in for the night, flocks may circle the roosting area as birds arrive from different directions and sort themselves out. This circling tends to be lower-energy than food-related spiraling. The birds call to each other but do not dive or compete. The flock gradually descends and lands rather than maintaining altitude.
Roosting flocks can be enormous, sometimes numbering in the thousands, and they tend to use the same sites night after night. If you notice a large circling flock that always appears over the same lake, reservoir, or rooftop complex in the evening and dissipates by morning, you are likely watching a roosting assembly rather than a feeding event. These gatherings serve a social function: birds that roost together may share information about productive foraging sites, and the colony structure that makes gulls such effective social foragers depends on these regular aggregations.
Why Gulls Seem More Common Than They Used To
If you feel like you are seeing more circling gulls than you did a decade or two ago, you might be right, depending on where you live. Several gull species have shifted their habits toward human environments over the past few generations. Roof-nesting herring gulls and lesser black-backed gulls have become fixtures in many European and North American cities. The reasons are straightforward: urban areas offer abundant food from waste, warm rooftops for nesting, and fewer predators than traditional coastal breeding sites. The same GPS research that documented gulls tracking human activity patterns also showed that urban gulls concentrate their movements around human infrastructure rather than natural foraging grounds.3PubMed Central. Urban gulls adapt foraging schedule to human-activity patterns
The thermal-soaring advantage of cities reinforces this trend. Built-up areas not only supply food but also provide the rising warm air that makes travel between food sources cheaper in energy terms.2PubMed. Built up areas in a wet landscape are stepping stones for soaring flight in a seabird A gull nesting on a warehouse roof in a city center can soar from thermal to thermal across town, check several known food sources on a learned schedule, and return to its nest with minimal effort. That is a hard deal to beat compared to commuting from a cliff face to open ocean and hoping to find a fish school.
When Circling Gulls Might Signal Something Unusual
Occasionally, circling gulls mark something other than routine foraging or soaring. A tight, low, agitated circle of gulls with loud alarm calling can indicate a predator nearby, such as a peregrine falcon hunting over a coastal area or a large raptor passing through. In that scenario the gulls are mobbing the threat rather than feeding, and you can usually spot the predator at the center of the commotion if you look carefully.
Large numbers of gulls circling over an otherwise unremarkable stretch of ocean sometimes indicate the presence of a marine predator driving baitfish to the surface. Whale watchers and recreational fishers know to watch for bird activity as a signal of what is happening underwater. A sudden dense cloud of circling gulls and terns in open water can mark a feeding whale, a school of dolphins, or a blitz of predatory fish like striped bass or bluefish. The birds are not circling for the marine predator itself but for the small fish being pushed into easy reach.
In rare cases, circling over a fixed inland location that is not an obvious food source can indicate a dead animal. Gulls are opportunistic scavengers, and a carcass in a field or on a roadside will attract a circling flock in much the same way a landfill does, just on a smaller scale. If the circling is focused on a very specific point and the birds keep landing and taking off rather than spiraling upward, something on the ground is worth investigating.
Gull Intelligence and Flexible Problem-Solving
One reason gulls are so conspicuous as circling flocks is that they are genuinely clever birds with a wide behavioral toolkit. Seabird researchers have noted that gulls can flexibly deploy a combination of foraging tactics depending on what is available, switching between scavenging, kleptoparasitism, diving for fish, and probing mud for invertebrates as circumstances change.1Biological Reviews. Social interactions and information use by foraging seabirds Their extended juvenile period, which can last several years before full adult plumage and breeding, gives young birds time to observe experienced adults and experiment with different strategies.
This flexibility means gulls are quick to discover and exploit new food sources. A construction project that exposes soil full of grubs, a food festival in a park, a change in garbage collection schedules: gulls notice these things fast and recruit others through the same social signaling that produces the circling flocks you see. The behavior that looks chaotic from the ground is actually an efficient information-sharing system honed by millions of years of colonial living. Each bird in the circle is simultaneously exploiting a resource and, by its visible presence, advertising that resource to every other gull within visual range.