210 THE SHELDUCK AND SURFACE-FEEDING DUCKS 



centres, but the nest feathers are quite distinctive, ' being white, sometimes with 

 grey centres, which spread to the top of the web' (Noble.) The eggs are 6 or 7 

 to 10 in number, creamy white in colour. Average size of 100 eggs, 2-16 x T52 in. 

 [54'9 x 38*7 mm.]. (PI. T.) Incubation is performed by the duck alone, and 

 lasts 22 to 23 days (Heinroth) ; 24 to 25 days (Naumann). In Scotland the full 

 clutch may be found occasionally as early as the first week of May, but more 

 usually about the middle of the month, and sometimes even in early June. On 

 the Shetlands Saxby records eggs as early as April 26, but in Northern Russia 

 the eggs are often not laid till the end of June. Only one brood is reared in the 

 season. [F. c. B. J.] 



5. Food. Grasswrack (Zostera) and other marine algse, fresh- water sub- 

 merged weeds, fine turf, cockles and other Mollusca, and small Crustacea. The 

 young feed mainly on small Crustacea, and accompany the female in their search 

 for food. [w. P. P.] 



