Innholdsfortegnelse for Gulls and Terns i Bird ID Photo Guides

Basic Principles Terns are known to undertake some of the most spectacular migratory journeys in the animal kingdom. These movements make them more likely to stray and be observed far from their normal ranges. Recent genetic research has recently redefined the boundaries between a group of species commonly referred to as the ‘orange-billed’ terns, of the genus Thalasseus. We discuss here the identification of species which have either already been observed in Britain or which could likely appear here. Elegant Tern This species breeds on the west coast of North America, from southern California to Baja California, Mexico, mainly on Isla Rasa in the Gulf of California, which hosts more than 90% of the world’s breeding population. Outside the mating season, it is distributed along the Pacific coast of America…

Basic Principles Similar in size, structure and appearance, Black-headed and Bonaparte’s Gulls are essentially equivalents primarily separated by range: the former inhabits the Old World, the latter the New. Black-headed Gull This species breeds extensively from western Europe eastwards across Eurasia to the Russian Far East. Most are migratory (or at least dispersive). Birds are present in Europe year round, although many move as far south as sub-Saharan Africa, while eastern birds head south to winter along the coasts of the Indian Ocean, China and Japan. The species is extremely common, with a worldwide population estimated as high as nine million birds (BirdLife International 2012). Britain represents an important cornerstone for Black-headed Gull, with an estimated 140,000 breeding pairs. In winter, the population swells to around two million individuals. As…

Basic Principles If you still need a good reason to start looking at gulls, here is one: you can expect the unexpected. Like many seabirds, gulls are capable of wandering all over the globe in different directions, and this can result in some real surprises. Slaty-backed Gull is a good example. Who would expect a big gull from eastern Kamchatka in Latvia? How about London? Or the west coast of Ireland? Yet, all that happened. Before 2008, Slaty-backed Gull was unheard of in Europe, but in just a few years birds have turned up in seven different countries. This is definitely a species to look out for, and the good news is that, despite being a large gull with variable immature plumages, it is actually quite distinctive. To help you…

Basic Principles Gull identification divides birders more than almost any other discipline – people either love it or hate it. But it needn’t be so controversial, and those who are put off by myriad plumages and variability should take comfort from the fact that there are ways of simplifying the identification process. You don’t need to be an instant expert: instead, you can build up your knowledge of the subject in layers. Understanding plumage terminology and the basics of moult will also make the task of identification more straightforward – this is especially so in a group as variable as gulls, which have multiple age classes (four in the case of Caspian Gull Larus cachinnans and its close congeners) and exhibit significant seasonal and individual variation. The aim of this…

Basic Principles Before we try to identify out-of-range Kumlien’s Gulls, it would be good if we could somehow define the taxon. This is where the problems start, however. The only thing we know for sure is that, even in this modern age of high-tech birding, Kumlien’s Gull remains a big mystery. Research on the topic has been hampered by the inaccessibility of both the species’ high Arctic breeding areas and its breeding habitat of tall and steep cliffs. If you want to study these birds, it seems you’ll need a sled with huskies, a friendly Inuit companion, professional climbing gear and plenty of thermal underwear! There has also been some controversy among researchers, one accusing the other of having fabricated his data to an unknown extent (see Snell 1989, Smith…

Basic Principles The so-called ‘marsh terns’ are always a delight, typically seen feeding low over water with a buoyant, erratic flight and dipping delicately to the surface in the manner of a Little Gull. This article focuses on three species: one regular, Black Tern; one scarce, White-winged Tern; and one rare, Whiskered Tern. Black Tern Nominate Black Tern breeds from western Europe east to central Russia and winters in Africa. The subspecies surinamensis (‘American Black Tern’) breeds in North America and winters south to Central and South America. Black Tern is an exceptionally rare breeding bird in Britain, but a regular passage migrant in both spring and autumn. South-easterly winds, particularly in May, can trigger occasional large influxes. It occurs commonly on coasts but is often seen inland too; indeed…

Basic Principles Always a favourite with birders, Little Gull is an elegant, attractive and charming species that invariably brightens a day’s birding. It can be found in Britain year round, although its numbers and distribution vary considerably, both with the season and prevailing weather conditions. In contrast, the other two potential confusion species featured here, Black-headed and Bonaparte’s Gulls, are abundant and rare respectively. Little Gull This species breeds colonially in freshwater marshes across Eurasia, where it can be quite common, and also in North America, where it is rare and localised. Despite several previous attempts, Little Gull only bred successfully in Britain for the first time in 2016, when two youngsters fledged in Aberdeenshire. Though not a regular breeder here, non-breeding immatures can routinely be found across Britain and…

Basic Principles Gulls offer seemingly endless challenges to birders of all skill-sets. For this reason many see them as a daunting and unattractive prospect, yet they need not be. Not all gulls require intense scrutiny of tertials, greater coverts and tail-bands to be identified; many species, while similar, are pleasantly distinct, especially with good views. Gulls are also some of the most accessible of all birds – favouring easily watched urban and suburban areas, they are often quite habituated to man, providing great opportunities for study. The three species covered here are prime examples of that – the two common species (Common and European Herring Gulls) can be found just about anywhere, thus meaning the scope for encountering the rarer taxon (Ring-billed Gull) is wide. Common Gull This species is…

Basic Principles The southern counterpart of European Herring Gull Larus argentatus, with which it was formerly treated as conspecific, Yellow-legged Gull L michahellis has a breeding range centred on the Mediterranean basin, extending east to the Black Sea and north up the French Atlantic coast to Brittany (nominate michahellis), and west to the Atlantic islands (subspecies atlantis). After breeding, dispersal of adult birds and then juveniles includes northwards movements to Britain, with considerable numbers at favoured coastal and estuarine locations in southern England during late summer and early autumn, before tailing off through the winter. Birds also penetrate inland in smaller numbers. The species becomes progressively rarer farther north and is very unusual in Scotland, where it was first recorded as recently as 1989 (Forrester 1995). It is an uncommon…

Basic Principles One of the greatest delights of summer is the presence of terns around our coasts. The set of three ‘medium-sized’ species – Common, Arctic and Roseate Terns – presents some complex identification problems. Traditionally, field guides emphasise bill colour and pattern, but in reality these species are usually seen in flight and at range. It is best to focus on structure, flight action and plumage. Common Tern This species has a large distribution, breeding right across Europe and Asia, and also North America. It is a long-distance migrant, with British birds wintering in West and South Africa. It is the commonest of the three medium-sized tern species in most of Britain. It breeds coastally, but also inland on lakes and reservoirs, the only species in the trio to…

Basic Principles Two New World gull species – Franklin’s and Laughing Gulls – are rare vagrants to Britain and Ireland. The total number of records of the former across both countries is around 120, with Laughing more than twice as regular, with some 260 accepted occurrences. This discrepancy belies the truth somewhat, though, as the devastating Hurricane Wilma led to an unprecedented invasion of Laughing Gulls in early November 2005 – perhaps as many as 70 individuals arrived on these shores, many of which went on to winter. In reality they are roughly as rare as each other nowadays, with one or two of each seen in an average year – although both species are seemingly prone to small influxes, presumably dependent on conducive weather conditions leading to arrivals in…

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Basic Principles Two Arctic-breeding gulls – Glaucous and Iceland Gulls – provide a welcome tonic in the often-murky world of large white-headed gull identification. They are highly distinctive in all plumages from the more familiar European Herring and ‘black-backed’ gulls, not least for their predominately white plumage – the most striking feature being the white rather than black primaries, which lends them the collective term of ‘white-winged gulls’. This generally makes them instantly recognis-able and easy to pick out from the crowd, both at rest and in flight. This is most pronounced at an evening gull roost, where they will often appear to glow in the twilight. While good views will generally allow the two species to be distinguished from each other with relative ease, this isn’t always the case.…