Every summer thousands of visitors flock to our seaside resorts – loud and confident, swaggering around gorging on ice cream and chips. No, not holidaymakers but herring gulls. One of our most familiar, and possibly least popular, birds, they are the quintessential sight and sound of the British coast.

Yet despite their seeming abundance, these raucous and resourceful members of the gull family have suffered alarming population declines in recent years, plummeting in number since the late 1960s to such an extent that they have been placed on our national "red list" of bird species of the highest conservation concern.

Where they are thriving is where we want them least of all – in our towns and cities. Exchanging sea cliff nest sites for rooftops, and fresh fish for the contents of our bins, their noisy, messy and occasionally aggressive behaviour has brought them into conflict with people. Rather than lament their widespread collapse, some would gladly see the back of them.

Love them or loathe them, herring gulls are undeniably impressive birds. Large and powerful, with silver-grey backs and the kind of clean white plumage that would look good on a washing powder advert, they are effortless in the air, riding ocean storms or slipstreaming ferries. Their evocative yelping cries, as heard on the theme tune to Radio 4's Desert Island Discs, provide the soundtrack to seaside holidays.

They are also intelligent and opportunistic. When it comes to finding a meal, their techniques include dropping shellfish onto rocks to break them open, trailing tractors for ploughed-up invertebrates, paddling the grass in playing fields to coax worms from the soil – and swooping down to snatch food from unwary passers-by.

For such a ubiquitous bird, the herring gull seems a little out of place alongside the bittern, corncrake and cuckoo as a cause for conservation attention. However, its population decline of more than 50 per cent in the past three decades qualified it for inclusion last year on Britain's ever-growing red list.

In order to identify which of our birds are most in need of help, a partnership of organisations including the RSPB and British Trust for Ornithology (BTO), periodically scrutinise the status of over 245 of our regularly-occurring species, putting them in either green, amber or red categories. The red list section of this Birds of Conservation Concern report comprises, for the most part, those species whose population or range has more than halved over the preceding 25-35 years – a substantial drop over a sufficiently generous time span to iron out short-term fluctuations – and currently totals 52.

More than 130,000 pairs of herring gulls breed in Britain, and five times that many individuals spend the winter here, boosted by feathered visitors from Scandinavia. As red list species go they are certainly some way off extinction in the UK. But when compared with their soaring numbers throughout much of the 20th century, their future is now far less secure.

Predators such as foxes and mink have had an impact, as well as avian botulism, a bacteria picked up from warm contaminated water which has led to deaths, particularly in Ireland. More significantly, according to experts, the rise and fall of herring gulls is closely tied to the fluctuating fortunes of commercial fishing. "They are a familiar sight swirling in clouds around trawlers returning to port, and their numbers certainly built up on the back of the growth in the fishing industry," says Grahame Madge, the RSPB's spokesman. "It provided them and other sea birds with discards of undersized fish and with offal as catches were cleaned at sea. But as the industry has declined along with fish stocks, the feeding opportunities for gulls have reduced, and that will have played its part in the decline of the herring gull and other birds such as the fulmar."

If herring gulls reaped the benefits of our wasteful approach at sea, then they have also done much the same inland, plundering rubbish dumps that became a rich source of scraps after the 1956 Clean Air Act prevented the burning of domestic refuse. Targets to reduce biodegradable waste at landfill sites mean these opportunities for free lunches may also diminish.

While still predominantly a coastal bird, city living has proved to their liking, as it is relatively free from predators and offers local sources of food, with street lighting enabling birds to pilfer late-night takeaway leftovers. A few took to rooftop nesting in the 1920s, and the habit spread so that today thousands of pairs breed in built up areas and raise young that largely grow up as committed townies. The catch-all term "sea"gull has become, for them at least, something of a misnomer.

The behaviour of these urban invaders isn't always as neighbourly as it could be. Corrosive splotches of guano on cars and menacing dive-bombing in defence of their chicks, raids on dustbins and ear-splitting calls at the break of dawn are the stuff of Asbos. As a result all manner of tactics have been deployed to deter them, including fitting plastic eagle owls to chimneys or broadcasting taped distress calls, but this can simply push the problem from one rooftop to another.

According to urban gull expert Peter Rock, who has spent the last 30 years ringing and studying them, the numbers of herring gulls and their close relatives lesser black-backed gulls are rising "exponentially" in the cities they have colonised, such as Gloucester, Bath, Bristol, Aberdeen and Cardiff.

He argues that the future management of urban gulls must be based on "science rather than guesswork", and has applied in conjunction with Bristol University for funding to study their feeding habits and economic impact.

"I don't think we will ever be entirely rid of them," he says. "We will find a way of managing them so they are less successful. It is not going to be cheap and it is going to be a long haul."

In response to their wider population decline, Natural England this year tightened up the licensing controls for those wanting to eradicate herring gulls as a pest – a move that has been welcomed by the RSPB.

"In certain situations, such as airport or hospital environments, there can be a case for culling them," says Madge. "But what we have never been comfortable with is destroying gulls for spurious public health and safety reasons or in nuisance situations such as nesting in towns and waking people up.

"We have always had a great deal of sympathy for those who are troubled by these birds. They can be a nuisance and we have never shied away from that. But if we just try to remove the bird we are not removing the problem. The reasons they have adapted to urban environments is that there is plenty of food around. Our throwaway culture is providing them with an easy living. The ultimate objective should be to see the native population build up in coastal colonies, where they will present less of a problem."

Given the part we play in providing for herring gulls, we can never know what the perfect natural target population should be. But the fact that they continue to rapidly lose ground demonstrates that even relatively common species can never be taken for granted. One in five British bird species have halved in number or range over the last 25 years.

Niall Burton, the BTO's head of wetland and marine research, says data from repeated seabird survey work has shed light on the plight of herring gulls. "We should be concerned if previously abundant species are in steep decline, be they herring gulls or house sparrows, because it suggests there is something wrong with their environment," he says.

"Herring gulls are a familiar element of seaside holidays and it would be a great shame if their numbers were to reduce still further."

Few birds are as self-assured and approachable, which allows us to appreciate herring gulls at close quarters: their diligent parenting, complex interactions and smart appearance (that red spot near the tip of their bill acts like a vending machine button – a tap on it from their young prompts adults to regurgitate food). They are also quick to learn, and this, coupled with a lifespan of up to 30 years, may help coastal populations exploit new sources of food and make good recent losses.

Whether encountering them on mudflats or multi-storey car parks, herring gulls are always worth a second look – perhaps now more so than ever, in the knowledge that despite their fierce expressions and anti-social tendencies, they have been having a tough time of it lately.