Gulls allowed?

18 Aug 2015
Lesser Black-backed Gull. Photograph by Sam Whitfield

Recently, typical reports of postmen refusing to deliver mail close to angry gulls’ nests have been surpassed by high profile reports of attacks on people and pets. These stories have prompted David Cameron to call for a “big conversation” on gulls amidst public demand for control measures ranging from egg oiling to widespread culling.

No single 'seagull'

It is easy to lose sight of the science amid these headlines, so as an evidence-based organisation, we feel it’s important to provide some scientific context to the stories. Firstly, whilst the headlines often speak of 'seagulls', this term could refer to any of the more than 50 species of gull found worldwide, distributed across a range of habitats from the Poles to the tropics. Some of these species spend much, if not all, of their lifecycle away from the sea.

In Britain, we have six species of commonly occurring breeding gulls – the Herring Gull, the Lesser Black-backed Gull, the Great Black-backed Gull, the Black-headed Gull, the Common Gull and the Kittiwake. We also have a small, but growing, breeding population of Mediterranean Gulls, and a handful of confirmed or suspected breeding attempts from Yellow-legged Gulls and Little Gulls. Several other species of gull commonly (or rarely) grace our skies outside the breeding season (approximately April to July), including Iceland Gull, Ring-billed Gull, Ivory Gull and Ross’ Gull. Of these species, it is the Herring Gull and Lesser Black-backed gull that get the majority of the bad press in Britain during the summer months. These species are similar in size, with a wingspan of approximately 1.4 m, and both have increasingly been nesting on urban rooftops since the mid-twentieth century, drawn to towns and cities (and thriving there) because of suitable nesting habitat, ample food and a relative absence of predators. The last major British seabird census, Seabird 2000, found that up to 10% of Lesser Black-backed Gulls were nesting in urban habitats and suggested this figure was growing rapidly. The next seabird census, planned to begin in 2016, is urgently needed in order to understand how this population has changed since the turn of the century.

Gulls are long-lived birds that typically return to the same area to nest year after year, laying clutches of one to three eggs. On reaching maturity, gulls will often return to breed in the vicinity of where they hatched, so breeding colonies can become rapidly established if breeding success and annual survival is high. Herein lies the root of the conflict with humans; during the breeding season gulls can be very vocal and messy, leading to complaints about noise and mess close to their nests. Furthermore, Herring and Lesser Black-backed Gulls vigorously defend their eggs and chicks, swooping down on perceived attackers, although it is worth noting that birds very rarely make contact with their target, and if they do, it is with their feet, and not (as is often reported) with their beaks. This defensive behaviour typically lasts for a few weeks, peaking around the time that eggs hatch in late-May/early-June, with another peak when the chicks fledge about a month later. Birds only act to deter perceived threats when they are close to their nests or chicks, so provided people move away, gulls will not do more than scream and swoop. This behaviour can certainly feel unsettling to humans, but it is not in the adult gulls’ interest to mount prolonged attacks – they have vulnerable young to care for, so will return to the nest as soon as the threat has passed.

Opportunistic eaters

Media reports often conflate this defensive behaviour with gulls’ normal feeding behaviour. Herring and Lesser Black-backed Gulls feed opportunistically on a range of foods from carrion to grain, and fish to invertebrates. Gulls are also predators, and will eat mammals like Rabbits and Moles. This predatory behaviour might explain the high profile attack on a Chihuahua puppy in Devon earlier this year, although it must be noted that such attacks are extremely rare, and given that gulls commonly fall prey to Foxes in rural colonies, most dogs would very likely get the better of a gull in a head-to-head. Gulls naturally take part in “feeding frenzies”, where several individuals (often of many species) will gather together to exploit a feeding opportunity, diving down to grab food and attempting to steal it from one another. In towns and cities, gulls display this behaviour when food is dropped, and also when people feed them, which is often the case despite local authorities’ efforts to discourage this habit. Urban gulls become habituated to humans, especially when they are commonly fed, and some individuals therefore take the opportunity of grabbing food from humans who do not intend to feed them, leading to complaints about gulls stealing chips. It is worth noting that individual gulls often have feeding specialisations, so not every urban bird will steal food – many will fly long distances to rural, coastal and maritime areas to eat very different foodstuffs, as our work tracking gulls with GPS shows. Also, birds’ feeding behaviour changes at different times of the year, with the dietary needs of chicks dictating adult foraging decisions in the breeding season. Further tracking work will be extremely valuable in understanding more about how gulls behave in urban environments. Outside the breeding season, many gulls remain in urban areas, but their non-breeding behaviour does not attract the same amount of negative attention from the public or the press, largely because birds are quieter and less territorial.

Protections and controls

All British gulls are protected by the European Birds Directive (2009/147/EC) which is transposed into UK law by the Wildlife and Countryside Act 1981 (as amended) and makes it an offence to kill or injure these species, and destroy their eggs or nests. However, licences can, and are, obtained to control gull populations. The Lesser Black-backed Gull can be controlled under three General Licences issued under the WCA 1981, which (consistent with the Birds Directive) allow the killing of birds or destruction of eggs/nests in certain circumstances, for example in the interests of public health and safety, if not on a protected site. The Herring Gull's licensing status was changed in 2010 because of conservation concerns. It is on one General Licence, allowing the destruction of eggs/nests (but not the killing of birds) for public health and safety reasons, and can also be controlled under a Class Licence. Control options include culling and measures to interfere with nesting (such as egg oiling to prevent hatching). Breeding gulls can also be discouraged by making the habitat less attractive, for example by minimizing and dealing efficiently with waste in urban areas so food is less available.

The Herring Gull in on the current UK Birds of Conservation Concern Red List, while the Lesser Black-backed Gull (and several other gull species) are Amber Listed. The latest figures from the Seabird Monitoring Programme show that breeding Herring Gull numbers fell by 30% between 2000 and 2013 (down from 140,000 pairs), and Lesser Black-backed Gull numbers were down by 48% (from 112,000 pairs) over the same period. These declines mostly reflect drops at rural and coastal breeding colonies, while the urban populations are thought to be rising, but we need the results of the next seabird census to establish exactly how populations are changing in different parts of these species’ ranges. A proper understanding of population trends is essential in any big conversations about gulls. This information should be carefully considered in any decisions about how, when and where, to control gulls, while a thorough understanding of their ecology should underpin any measures taken.

If you would like help learning to separate the gull species found in Britain, many are covered by our ID video tutorials on small black-headed gulls, Kittiwake and other small gulls, Iceland and Glaucous Gulls and most recently - adult black-backed gulls.

By Viola Ross-Smith and Aonghais Cook

References

Balmer, D.E., Gillings, S., Caffrey, B.J., Swann, R.L., Downie, I.S. & Fuller, R.J. 2013. Bird Atlas 2007–11: the breeding and wintering birds of Britain and Ireland. BTO Books, Thetford.

Burton, N.H.K., Banks, A.N., Calladine, J.R. & Austin, G.E. 2013. The importance of the United Kingdom for wintering gulls: population estimates and conservation requirements. Bird Study 60, 87-101.

Camphuysen, C.J., de Boer, P., Bouten, W., Gronert, A. & Shamoun-Baranes, J. 2010. Mammalian prey in Laridae: increased predation pressure on mammal populations expected. Lutra 53, 5-20.

Camphuysen, C.J. & Gronert, A. 2012. Apparent survival and fecundity of sympatric Lesser Black-backed Gulls and Herring Gulls with contrasting population trends. Ardea 100, 113-122.

JNCC 2014. Seabird Population Trends and Causes of Change: 1986-2013 Report. (http://www.jncc.defra.gov.uk/page-3201). Joint Nature Conservation Committee. Updated August 2014. Accessed 17th August 2015.

Mitchell, P.I., Newton, S.F., Ratcliffe, N. & Dunn, T.E. 2004. Seabird populations of Britain and Ireland. Results of Seabird 2000 (census 1998 – 2002). T. & A. D. Poyser, London.

Raven, S.J. & Coulson, J.C. 1997. The distribution and abundance of Larus gulls nesting on buildings in Britain and Ireland. Bird Study 44, 13-34.

Rock, P. & Vaughan, I.P. 2013. Long-term estimates of adult survival rates of urban Herring Gulls Larus argentatus and Lesser Black-backed Gulls Larus fuscus. Ringing & Migration 28, 21-29.

Ross-Smith, V.H., Robinson, R.A., Banks, A.N., Frayling, T.D., Gibson, C.C. & Clark, J.A. 2014. The Lesser Black-backed Gull Larus fuscus in England: how to resolve a conservation conundrum. Seabird 27, 41-61.