326 Bonn, Nuptial Performances of the Sage Cock. aoe 
found on page 406 of Dr. Coues’s ‘ Birds of the Northwest,’ nor 
have I ever found a wing of a Sage Cock, in this or any other 
season, which exhibited the slightest wearing away of the prima- 
ries. Instead of dragging its wings upon the ground the Sage 
Cock will enormously inflate the air sacks of the neck until the 
whole neck and breast is balloon-like in appearance, then stoop- 
ing forward, almost the entire weight of the body is thrown upon 
the distended portion and the bird slides along on the bare 
ground or short grass for some distance, the performance being 
concluded by the expulsion of the air from the sacks with a 
variety of chuckling, cackling or rumbling sounds. ‘This per- 
formance is continued probably daily, during the pairing and 
nesting season, and of course the feathers are worn away by the 
constant friction. 
The brush drawing (Plate XII) shows the position taken by the 
Sage Cock while engaged in the eccentric performance described 
above, while the line drawings show the effect of the sliding friction 
upon the feathers of the inflated area. These drawings (Figs. 
1-3) were made of feathers taken from an old Sage Cock killed 
in December and the question arises —are these feathers ever 
moulted, and if so, when? Fig. 1 is the type of feather which 
almost surrounds the air sacks, when the same are exhausted, 
for the space of an inch or more. These are evidently worn 
half away. Fig. 2 is a type of the next circlet below, and Fig. 
3 of those just above (or just below when the bird stoops forward) 
