210 



of construction, whereas in others there were nestlings, and even 

 full-fledged birds. 



The nests were almost invariably located in the fork of a birch- 

 tree, between the stem and one of the principal branches, and at 

 some distance from the ground, often upwards of ten feet. They 

 were seldom seen lower down, in woods of vigorous growth: in 

 brushwood, on the other hand, they often lay less than a foot from 

 the ground. The exterior portion of the nest is constructed of 

 lichens and the stalks of a Poa, frequently on a thickish laver of tine 

 dry birch twigs; the inside is well lined with feathers of the ptar- 

 migan and the down of Salix lanata and Eriophorum. 



The number of eggs in one^ nest did not, I found, exceed 5. 

 Botn parents sat in turns, the male keeping watch for hours to- 

 gether at the side of his mate. Average length of the eggs 16 

 by 127 2 mm. 



In nestlings, scarcely more than three days old, sand was in- 

 variably found in the stomach, the craw being crammed full of 

 insects or the green-coloured larvæ of a Geometra, very numerous 

 on birch-leaves. 



In smaller flights, consisting of sterile individuals, it oceurs 

 throughout the summer off the breeding haunts, frequenting even 

 the naked rocks and islets on the ocean-bank; such is the case, 

 for instance, at Stappen, close to the North Cape, where this bird 

 never breeds nearer than at a distance of several miles. Also in the 

 deep vallies of the south, where the species never breeds, — the 

 fells being its only breeding haunt, - stray flights are annually 

 seen; in some years, vast numbers stav behind on the low lands 

 (vicinity of Christiania 1863 and 1868), and are then distinguished 

 by a very peculiar plumage (described in Nyt Mag. f. Naturv. Vol. 

 18, p. 175), widely distinct from the summer garb. 



The chief detachment of the individuals breeding in Finmark 

 migrates to the south at the approach of winter: large numbers 

 however, remain behind, their food then consisting of the seeds of 

 the birch. 



