LIFE HISTORIES OF NOKTH AMEBICAN DIVING BIRDS. 217 



Nesting.— Mv. W. Elmer Ekblaw contributes the following ex- 

 cellent account of the nesting habits of the dovekie: 



The nesting sites are determined probably by several factors, perhaps of 

 equal significance. These sites are always along clifes with rather steep talus 

 slopes, of rather large fragments, ampng which the birds can find entrances, 

 and cavities well enough within shelter to be safe from winds and weather 

 and predatory animals. In suitable talus slopes Its nests extend from near the 

 high tide water mark to the top of the slope, in every possible place. Because 

 of the slow disintegration of the rocks, as compared with the breaking off of 

 the fragments from the cliffs, the talus slopes are piles of coarse rocks with 

 cavities, passages, crevices, and tunnels everywhere among them. In these 

 cavities and passages at various distances from the outside, according to the 

 convenience and safety of the place, the nests are placed.' Frequently a mat 

 of grass grows over the surface of the rocks, but since it is only a superficial 

 mat, and as long as openings are left for the ingress of the birds, this does not 

 detract In the least from the desirability of the site. Along Foulke Fjord, 

 on the cliffs south of Cape Alexander, and near Sonntag Bay I have found 

 thousands nesting on what was apparently only a grass slope with an occa- 

 sional projecting rock, but examination revealed the fact that it was only a 

 concealed talus slope after all. Where the breaking down of the cliff above, 

 or where there is considerable rolling of the surface rocks, the grass does not 

 form, though upon the margins of the talus tongues, and in a semicircle about 

 their terminations when they do not reach the sea the grass mat encroaches. 

 In a few cases the grass mat has so deeply covered the talus that the auklets 

 have abandoned it, because they could not enter. Not only in the talus piles 

 does the dovekie nest, but also in crevices — almost without exception In hori- 

 zontal crevices — It makes Its home as well; but this only when talus slopes 

 near at hand have nests too, for this Uttle bird is most socially Inclined, nest- 

 ing, feeding, swimming, flying, and migrating in great gregarious flocks. 



It builds no nest. Its one egg, or rarely two, is laid on a rock or shelf in a 

 passageway or cavity, usually In a niche along, or at the end of, a passageway. 

 This rock, after many generations of auks have nested there. Is covered with 

 more or less damp dung, upon which the egg or eggs are laid. Several nests 

 may be very close together, or considerable interval may occur between a nest 

 and its neighbor. The entrance to a nest Is usually marked by a white patch 

 on the rock, where more than the usual amount of dung is deposited, for when- 

 ever one of the old birds alights at the entrance, he, or she, almost invariably 

 defecates. The earliest eggs are laid in the last week of June, but it is during 

 the first week of July that laying Is at Its height, at Btah. In the last week In 

 June the Eskimo women begin gathering the eggs, but they are not so plentiful 

 as they become a week later. Each female lays one egg and this is the usual 

 number. Rarely two eggs are laid, and in four cases of this that I saw the 

 eggs were slightly smaller than the normal egg. 



Eggs. — ^The single egg is " ovate " or pointed ovate va. shape. Its 

 shell is smooth but without luster. All the eggs that I have seen are 

 plain bluish white and immaculate; I have never seen any of the 

 alleged spotted eggs of this species. The measurements of M eggs, 

 in various collections, average 48.2 by 33 millimeters; the eggs show- 

 ing the four extremes measure 51 by 34, 49 by 35.5, 45 by 33, and 46 

 by 32 millimeters. 



