The following has been adapted from original text by Robert W. Furness and Norman Ratcliffe in Seabird Populations of Britain and Ireland (with permission from A&C Black, London). The influence of territory density on the vulnerability of Arctic skuas Stercorarius parasiticus to predation. In Northern Ireland, great skuas are a recent colonist, first nesting on Rathlin Island in 2010. Breeding skuas in Orkney: a 2010 census indicates density-dependent population change driven by both food supply and predation. Skuas are top predators in marine ecosystems and may have detrimental effects on seabird communities they prey upon. The annual sample of great skua colonies is insufficient to produce reliable trend information because only few major colonies are surveyed frequently, or in the same year, so the trend since the last census is largely unknown. The great skuas gather in flocks of about 40 or more over shoaling fish. The Skuas. Journal of Animal Ecology, 87(6), 1573–1586. Journal of Zoology, 223, 175–188. Western Isles Birds - Great Skuas - very powerful majestic seabirds - in and around The Western Isles. ProductivityThe productivity of the recent colonists has been closely monitored. 9 Meek, E.R., Bolton, M., Fox, D. and Remp, J. In breeding areas on coastal rocky islands and moorland; at other times seen around coasts, often in the neighbourhood of seabird colonies, scavenging from other birds, or picking food from the surface of the sea. colony) level9. 1998. Great skuas show little fear of humans – anybody getting close to the nest will be repeatedly dive-bombed by the angry adult. 12 Votier, S.C., Bearhop, S., Ratcliffe, N., Phillips, R.A. and Furness, R.W. Seabird Populations of Britain and Ireland. The great skua was described from the Faroe Islands and Iceland by the Danish zoologist Morten Thrane Brünnich in 1764 under the binomial name Catharacta skua. 18 Ratcliffe, N., Furness, R.W. Effects of Great Skuas on Arctic Skuas in Shetland. Trend in productivity (no. The Great Skua is the largest Skua in the Northern Hemisphere, 60% of the world population breeding in Scotland, The Western Isles, Shetland and Orkney, Breeding bonxies are relentless and ferocious in defence of their territory against human (or any other) intruders, especially when the chicks are young. Like other skuas, they will fly at the head of a human or other intruder approaching its nest. Outside the breeding season they are usually solitary, though will congregate if there is food.. Great skuas (or 'bonxies', a Shetland word meaning dumpy, untidy women) are majestic and powerful seabirds that never fail to provoke a reaction. Based on SMP data; view the methods of analysis. [11] Some authorities still regard the great skua as conspecific with some of these southern skuas, and as a group they have sometimes been separated in the genus Catharacta, although currently this taxonomy is not commonly followed. However, declines at the two largest colonies (Foula and Hoy) resulted in little overall change in AOTs across all colonies combined. Operation Seafarer (1969-70) did not attempt to find all inland nesting skuas so will have underestimated numbers by a small amount. Unlike Arctic skua, great skua colonies rarely suffer complete breeding failure. When the pair do have young they will "dive attack"anything from other birds, to even humans. 16 Church, C.E., Furness, R.W., Tyler, G., Gilbert, L. and Votier, S.C. 2018. It is now placed in the genus Stercorarius that was introduced by the French zoologist Mathurin Jacques Brisson in 1760. The great Skuas is the largest skua in the Northern Hemisphere, breeding each summer in northern Scotland, Iceland, and the Faeroe Islands. Annual monitoring data from six Arctic skua colonies in Shetland (Fair Isle, Fetlar, Foula, Hermaness, Mousa and Noss) between 2003 and 2018 recorded 43 cases of complete colony failure out of a possible 85 colony-years, not one instance of complete failure for the great skua occurred over the same period. Length: 53-66cm Wingspan: 1.3m Weight: 1.3-1.5kg Average Life span: 15 years. Ecology, 86, 1047–1056. First nesting in the late 1990s in the Republic of Ireland and colonising Northern Ireland in 2010. A common technique is to fly up to a gannet in mid-air and grab it by the wing, so that it stalls and falls into the sea, where the great skua then physically attacks it until it surrenders its catch. A study of abundance data in Scotland from 1992 to 2015 indicated that great skuas increased at most sites, with some very large increases at smaller colonies. Management implications of interactions between fisheries and sandeel dependent seabirds and seals in the North Sea. Increasingly, since the 1980s, it has become a major predator of seabirds, particularly in smaller colonies, such as those in the Western Isles (where approximately 6% of the population occur)5,6. They will also directly attack and kill other seabirds, up to the size of Herring Gulls. © Joint Nature Conservation Committee, Monkstone House, City Road, Peterborough, PE1 1JYTel: 01733 562626 Fax: 01733 555948. If 3 or more images are purchased the … The above data present a complicated picture with no clear trend; surveys at the remaining UK colonies, especially in other parts of Shetland and the Western Isles, are required to accurately assess the current population status of the great skua. Great skua diet varies geographically; in the Northern Isles, where about 94% of the UK breeding population occurs, great skua is a scavenger largely feeding on sandeels Ammodytes spp during the 1970s and on fisheries discards from the 1980s to the present day1,2,3,4. Temporal and spatial variation in the diet of a marine top predator – links with commercial fisheries. Since then, breeding attempts have been made by this single pair in most years, but they have only fledged chicks in 2014, 2015, 2016. 2002. On average, productivity measures 1.67 chicks fledged per pair per year. and Furness, R.W. May 2016. In addition, the great skua is a cold-adapted species which suffers heat stress during warm weather5. The Northern Ireland Seabird Report 2018. Like most other skua species, it continues this piratical behaviour throughout the year, showing less agility and more brute force than the smaller skuas when it harasses its victims. Identification of this skua is only complicated when it is necessary to distinguish it from the closely related large southern-hemisphere skuas.

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