NON-IiXDIGENOUS BRITISH BIRDS. 113 



hollow trampled down in the soil or moss, in which a 

 few feathers and pellets accumulate and form the only 

 bed on which the eggs repose. The eggs in most cases 

 appear to be laid in pairs at intervals, the bird com- 

 mencing incubation at once, so that by the time all are 

 deposited, some of the earlier ones may be hatched, and 

 the young assist in incubating the rest. Eggs and young 

 birds in various stages of growth may therefore be found 

 at the same time in one nest. The male bird keeps 

 jealous watch near the nest ready to defend it and beat 

 off any intruding creature, or to warn the female of the 

 approach of danger. She sits lightly, and is up at the 

 least alarm, the two birds careering wildly about round 

 the spot, screaming incessantly. 



Range of egg colouration and measurement : 

 The eggs of the Snowy Owl are usually from six to 

 eight in number, but ten have been found. They are 

 rather rough in grain, show but little polish, and are 

 white, often with a scarcely perceptible yellow tinge. 

 Average measurement, 2-3 inches in length by 17 inch 

 in breadth. Incubation, performed by the female, lasts 

 (in confinement) thirty-two days. 



Diagnostic characters : There is absolutely no 

 reliable character by which the eggs of the Snowy Owl 

 may be distinguished from those of the Eagle Owl (the 

 only species with which they can be confused in Europe). 

 Generally they are a little smaller than that bird's, which 

 also never show any yellow tint, and are more oval in 

 shape. The breeding grounds of the two species are 

 also quite difterent. 



