146 THE NESTS AND EGGS OF 



Breeding habits : Bewick's Swan reaches its Arctic 

 breeding grounds towards the end of May or early in 

 June, as soon as the south wind has sufficiently ensured 

 the presence of open water. Although gregarious on 

 migration, the bands disperse for the breeding season 

 and nest in scattered pairs. There can be little doubt 

 that this Swan mates for life, but builds a new nest each 

 season. Its breeding grounds are not known to differ 

 from those of the Hooper Swan — the shores of lakes on 

 the tundra, the banks of creeks, and scrub-clothed islands 

 in the deltas of the Arctic rivers. But little is known of 

 the habits and nest of this Swan, and its eggs, so far as 

 I know, have never been taken from the nest by any 

 scientific collector or naturalist. Eggs of this bird, of 

 whose authenticity there can be no reasonable doubt, 

 were brought to Messrs. Harvie-Brown and Seebohm 

 during their visit to the Petchora in 1875, which had 

 been obtained on the island of Pyonin in the delta of 

 that river; whilst others were secured under similar cir- 

 cumstances by Mr. Seebohm during his sojourn in the 

 Yenesay in 1877, taken from an island and from the 

 mainland near that river's delta. Natives describe the 

 nest as being like that of the Hooper Swan, and built 

 in a similar situation. This species is remarkably wary 

 at the nest. 



Range of egg colouration and measurement : 

 The full number of eggs in a clutch of this Swan is not 

 known with certainty, but more than three have not yet 

 been found in any one nest. They are almost pure 

 white. Average measurement, 4*0 inches in length by 

 2*6 inches in breadth. The duration of the period of 

 incubation is unknown. Probably the female undertakes 

 most of, if not entirely all the duty. 



Diagnostic characters : The eggs of this Swan 

 may be distinguished from those of the Hooper Swan — 



