HYBRID GROUSE. 581 
love-songs every day from the same tree, and these birds re- 
gularly return to their roosting-places in the evening, and in 
the morning conduct themselves just like the Capercaillies. 
Others, on the contrary, repair every morning to a certain 
drumming-place of the Blackcock, whether it be situated on 
a heath, a clearing, a glade, or a moor; there they drum in 
company with their smaller relatives, fight with them—gene- 
rally very valiantly,—and haunt the neighbourhood of the 
spot throughout the day, especially in the evening, conducting 
themselves in every respect just like the Blackcock. 
Their plumage, too, however much it may, as a whole, look 
like that of a special type, must, when viewed in detail, be 
recognized as a blending of that of both parents, for the feathers 
of the Capercaillie and the Blackeock are reproduced un- 
changed in the plumage of the Hybrid. Only in the ruddy 
sheen of the breast does it differ materially from the green of 
the former and the blue of the latter ; and it is just this remark- 
able reddish play of colour which is a constant characteristic 
of all Hybrid Cocks. The beak and the feet, too, as well as the 
whole appearance of the bird, undoubtedly form, both in size 
and shape, a true intermediate stage between the Capercaillie 
and the Blackgame. 
It is, however, the study of the skeleton that, above all, 
stamps the Tetrao medius as a cross; and I here give the 
varying numbers of the vertebrae in three of these birds which 
I got in Bohemia :— 
Vertebree of neck and back. | Caudal vertebra. 
Te 16 6 29 
cee 14 6 20 
EER. 14 ri 21 
