NON-INDIGENOUS BRITISH BIRDS. 289 



season permits. It is a gregarious bird, and breeds in 

 colonies of varying size. This species probably pairs 

 for life, and returns to the saine nesting places each 

 season, although further information is much to be 

 desired. I'his Gull breeds on cliffs in some localities, 

 on the ground in others. In some districts low flat 

 islands of sand in the deltas of rivers are resorted to. 

 When placed on the ledges of precipices it is a some- 

 what massive structure composed of dead seaweed and 

 drift, and lined with dry grass, but when on the ground 

 it is little more than a shallow cavity lined with a ^q\v 

 bits of dry grass. Nests found by Messrs. Seebohm and 

 Harvie-Brown on a sand-bank in the delta of the 

 Petchora, are described by them as heaps of sand 

 hollowed slightly at the apex, and lined with a few tufts 

 of coarse sea-weed. MacFarlane states that they were 

 mere depressions in the beach. This Gull is bold and 

 pugnacious at the nesting grounds, rising in flocks from 

 the eggs, and circling above the intruder, or swooping 

 past him uttering noisy cries. 



Range of egg colouration and measurement : 

 The eggs of the Glaucous Gull are two or three in 

 number. They are somewhat rough in texture, and 

 vary in ground colour from pale olive-brown of various 

 shades to pale bluish-green, spotted and blotched with 

 dark brown and with underlying markings of brownish- 

 gray. As a rule, the spots are not very large, and fairly 

 distributed over most of the surface of the ^gg, but less 

 frequently the markings are moderately large blotches 

 mostly on the major half, where they sometimes form 

 an irregular zone. I have examined eo-s^s from Vardo, 

 which are said to' belong to the Glaucous Gull, pale 

 red in ground colour, spotted with darker red and with 

 underlying markings of lilac-gray. Axerage measure- 

 ment, 3"0 inches in length, by 2*0 inches in breadth. 



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