Unidentified Glaucous/Iceland Gull

Unidentified Glaucous/Iceland Gull Larus hyperboreus/glaucoides Hvítmáfur/Bjartmáfur

As Glaucous and Iceland Gulls share identical plumage characteristics and differ only subtly in proportion, it is often difficult to differentiate the two species in the field, especially at distance, or when visibility is suboptimal. Therefore, the two species were grouped in October, when several tens of birds were present, and differentiating each individual bird in a flock was not practical. There was an influx of Glaucous /Iceland Gulls during October, and a peak count of 162 birds were recorded during the low tide survey on 9th October. These birds were distributed throughout the survey area, with the exception of Hvítárleirur (Est 5).

Number of individuals 200 150 100 50 0 Low-tide Rising-tide

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 Mar Apr May Jun Jul Aug Sep Oct Week number and month

Figure 3-121. Number of Larus hyperboreus/glaucoides recorded during weekly low tide and rising tide estuarine surveys in the Andakíll Ramsar site between 12th March and 25th October 2017.

(a) Low tide (b) Rising tide

Figure 3-122. Relative abundance of Larus hyperboreus/glaucoides during weekly (a) low tide and (b) rising tide estuarine surveys in the Andakíll Ramsar site between 12th March and 25th October 2017. Dots are randomly positioned within each subsite. While each dot refers to a single bird, it refers to the bird’s presence in that subsite only, and not the bird’s actual location.