Iceland Gull in St. Louis County
2010-12-05

'Rare Regular' in Minnesota

This fourth-cycle Iceland Gull was aged as not quite adult by the presence of an incomplete dark ring on the bill, dark markings in the outermost upper greater and median wing coverts, and presumably a non-definitive primary pattern. Although the non-black grayish-brown color of the markings in the outer primaries indicate an Iceland, the extent of these markings is more typical of Thayer's if in definitive/adult plumage (i.e., the white tongue tip on P10 is neither terminal nor joined with the white mirror on P9, and there is a small dot on P5; these features may either be a result of immaturity or past introgression with Thayer's Gull). This bird was one of a bewildering 33 different individual Iceland and Thayer's Gulls observed in Duluth on 5 December! This total includes 23 Thayer's Gulls (7 adults, 3 third-cycles, 3 second-cycles, and 10 first-cycles), at least 8 birds showing strong features of Iceland Gull (5 adults, 1 fourth-cycle, 1 second-cycle, and 1 first-cycle), plus both an adult and a second-cycle Iceland/Thayer's intergrade/hybrid. Some authorities consider these two species conspecific and many do not agree on the characteristics necessary to identify them.

Karl J. Bardon