180 BULLETIN 16 2, UNITED STATES NATIONAL MUSEUM 



as the set progresses, the birds mold it into the proper shape, and by the time 

 incubation has progressed, the eggs snuggle together in a well-cupped basin. 

 The brooding female spreads her feathers as does the sitting domestic hen, and 

 when her frail body is examined in hand, it seems almost incredible that she can 

 cover so large a clutch of eggs. The extreme measurements of 12 nests exam- 

 ined are : Total height, 5 to 7 inches ; inside diameter, C to 8 inches ; depth of 

 cavity, 3 to 6y 2 inches. 



F. Seymour Herse} T collected some 10 sets of eggs for me between 

 St. Michael and the mouth of the Yukon. They were mostly in 

 fairly open situations on the tundra. One nest was a depression in 

 the tundra moss at the base of a small clump of grass; it was lined 

 with dry grass, leaves, and a few feathers ; it measured 7 inches across 

 and 5 inches deep. Another was in a hollow under a dwarf willow on 

 a raised mound on the tundra. Another was in a deep hollow in a wet 

 place on the border of a marsh, a very open situation; it had a heavy 

 lining of dry grass and a few feathers. Some of the hollows were 

 very shallow, not more than 2 inches deep. There were three sets of 

 7, two of 8, one of 9, three of 10, and one of 11 eggs. 



George G. Cantwell writes to me of a nest he found on Copper 

 River, Alaska, that was " placed on an open river bar among a light 

 growth of willows, close to a growth of mountain spruce/' Stanton 

 Waiburton. jr., tells me of a nest he found late at night, saying: 



To preserve them intact for a photo in the morning, I put my khaki coat 

 over the nest and eggs, completely covering them. Then (as an experiment) 



1 wrinkled up the collar by the eggs so that it formed an opening not over 



2 inches high. This slight opening did not expose the eggs to view from any 

 angle, as they were still completely covered. Early the next morning when I 

 approached, the female flushed from right beside my coat. All 11 eggs were 

 now in a new nest just outside my coat, not over a foot from the original 

 location. During the night the female had made a new nest, moved all 11 eggs 

 into it, and recommenced incubation. 



MacFarlane mentions in his notes another case where the eggs 

 were probably removed by the birds. He " had reason to know that 

 some, at least, of the nests were used by ptarmigan several seasons 

 in succession." 



Joseph Dixon (1927) writes: 



The male ptarmigan spends the day hiding in little thickets, keeping within 

 50 or 100 feet of the nest. He has a definite form or nest of his own which lie 

 occupies when roosting. One reason for his staying so close is the danger of 

 Short-billed Gulls finding the ptarmigan's nest. These egg thieves work in 

 organized gangs, usually three together. One will swoop down at. the female. 

 trying to make her shift about on the nest so as to expose the eggs. The second 

 or third gull following tries to slip in and grab an egg. As soon as the gulls 

 appear, the hen ptarmigan gives a peculiar call for help. Upon hearing tins 

 the cock ptarmigan bursts forth like a rocket and charges the thieving gulls. 

 He doesn't beat around the bush but Hies directly at the intruders, knocking 

 them down with the impact of his body. An average cock Willow Ptarmigan 

 at this season weighs ;!07 grams, while one on the Short-billed Gulls which was 



