Fox, AD & Aspinall, SJ 1987. Pomarine Skuas in Britain and Ireland in autumn 1985. British Birds 80: 404-421.
"The year 1985 was an exceptional one in the Russian Arctic, enjoying both a fine early spring and, in many parts, a warm dry summer; coupled with this, it was a lemming year and it is tempting to speculate that Pomarine Skuas, being major predators on lemmings (Cricetidae) (Dementiev et al. 1969), would have had a good breeding season." (p. 419)
"In the early part of November 1985, there was a week of severe weather following the domination of a high-pressure system over the North Atlantic. The decay of this system led to a sudden rush of cold northerly airstreams, with gales of up to force 9 from the north and NNW. At a time when large numbers of Pomarine Skuas were present in northern waters, this resulted in the considerable influx along North Sea coasts." (p. 419)
Camphuysen, CJ & van IJzendoorn, EJ 1988. Invasie van Middelste Jagers in Nederland in november 1985. Dutch Birding 10: 54-66.
"An important cause of the influx is thought to have been a very successful and productive breeding season, owing to the fact that 1985 was a good lemming year in parts of the Siberian arctic (eg Taimyr peninsula) in combination with extremely good weather conditions during the arctic summer." (p. 66)