328 TETRAO LAGOPUS RUPESTRIS. 
terminate their flight by diving precipitately into the 
loose snow, endeavouring to escape by working their 
way beneath the surface, which they do with conside- 
rable celerity. In thick, windy, or snowy weather, 
they are very shy, and then often perch on the talb' r 
willows, when it requires a sharp eye to distinguish 
them from flakes of snow. In the breeding season, 
they feed mostly on the berries of the empetru 
nigrum , vaccinium vitis idaia, and arbutus alpina, which 
are exposed by the iirst thaws, and do not disappear 
until replaced by the new crop. At the commencement 
of this period they begin to lose their snow-white 
winter dress, the male changing first, his head and neck 
becoming red, and, when viewed from a distance, con- 
trasting so strongly with the white body, as to appear 
as if they were stripped of their feathers, and quite 
raw. The beginning of June is the period of incuba- 
tion, and the female then moults, the delay being 
admirably suited to her habits, and well calculated to 
ensure her safety. The male puts on his coloured 
plumage as soon as the rocks and eminences most 
exposed to the sun become bare, and at a time when ( 
he is accustomed to stand on a large stone, and call, i' 1 
a loud, croaking voice, to the females, that hide them- 
selves in their white dress among the unmelted sno"' 
on the more level ground. Like most other birds that 
summer within the Arctic circle, they are more in 
motion in the milder light of night than in the broad 
glare of day. I had no opportunity of seeing tlm 
eggs. The eggs are bright or dark yellow, with chestnut 
brown spots, or dots.” — Richardson. 
40. TETRAO (ZAOOPUS) RUPESTRIS, LEACH ROCK GROCSE- 
Rock grouse, Penn. Arct. Zool. 2, p. 312, N. 184 . — Tetrao 
lagopus, Ten an. 2, p. 468. 
“ This bird was first described by Pennant as a distinct 
species, principally on the authority of Mr Hutchins, 
and was adopted into the compilations of Latham and 
