The National Seabird 2000 census recorded 2,136 Arctic and 9634 Gt Skuas with 90% of the population in Orkney and Shetland
Full report https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.12890
Locations of Arctic skua colonies used in analyses of population trend (n = 33 sites) and annual productivity (underlined, n = 20 sites). Dotted line = southernmost extent of Arctic skua breeding range during Seabird 2000. Overall percentage change in Apparently Occupied Territories (AOTs) between the first and last year surveyed (1992 and 2008–2015) is given for each site (see Supporting Information Table S1 for further details). Symbol sizes are scaled to AOT counts in 1992 (four categories: 0–12, 16–26, 30–66, 101–159). Symbol shape denotes colony type, classified by cliff‐nesting seabird host abundance within 5 km of colony during the Seabird 2000 census: squares = type 1 colonies (>10,000 pairs), circles = type 2 colonies (1,000–10,000 pairs), triangles = type 3 colonies (<1,000 pairs)
Arctic Skuas declined at all the study colonies from 1061 ATO 's (1992) to just 200 in (2015), indicating the largest declines took place in the north with the largest productivity in Handa in NW Scotland.
Attacks on Kittiwakes which had only come down onto a loch to bathe
An Arctic Tern attacks an Arctic Skua
Gt Skua seen off by a Fulmar
In Orkney, a complete census revealed a 23% decrease between 2000 - 2010 (1,710 ATO's)
Discards from fishing boats used to be an important part of the Gt Skuas diet in Shetland but with the reduction of discards they have now started to either concentrate on attacking Gannet for fish, eating birds such as Puffin or resorting to cannibalism .
Having just taken part in the 2018 Seabird census I am very interested in seeing the current figures