LIFE HISTORIES OF NORTH AMERICAN DIVING BIRDS. 159 



of limestone rock 30 or 40 feet high, as we wallved along the stony- 

 beach below. Black guillemots were not common on this coast, prob- 

 ably on account of the scarcity of suitable nesting sites. 



On the northeast coast of Labrador, in the summer of 1912, we 

 found this species evenly distributed and one of the conmionest of 

 the sea birds, as far north as Nain. Mandt's guillemot is said to 

 breed in the northern portion of the coast also, but all that we shot 

 proved to be Cepphus grylle. They breed mostly on the outer 

 islands, which are bare and rocky, lajdng their eggs in remote cavi- 

 ties under the numerous piles of broken rocks or in crevices in the 

 rocky cliffs which are often inaccessible. Their eggs are persistently 

 collected for food all summer and it is a wonder that they are not 

 entirely exterminated. We found plenty of eggs which were nearly 

 fresh as late as the first week in August. We saw no young birds 

 anywhere, and probably only these birds that had selected inaccessi- 

 ble locations had succeeded in hatching any egg's. 



Eggs. — The black guillemot lays almost invariably two eggs, 

 though occasionally one egg constitutes a full set; where more than 

 two eggs are found in a nest, as some writers have reported, these 

 are probably the product of more than one female. The eggs are 

 handsome and boldly marked. The ground color is dull white, often 

 with a faint bluish or greenish tinge, sometimes " cream color," or 

 " cream buff." Some eggs are fairly well covered with small spots, 

 but usually the markings are grouped about the larger end, often 

 forming a ring, in large irregular blotches of dark shades of brown, 

 varying from " clove brown " to " sepia." One particularly hand- 

 some egg in my series is heavily blotched with " cinnamon," overlaid 

 with " chocolate," on a cream-colored ground, with numerous faint 

 spots of " lilac gray." Most eggs are more or less spotted and some 

 bre quite heavily blotched with "lavender" or "lilac gray" of 

 various shades. They vary in shape from " ovate " to " elliptical 

 ovate." The measurements of 54 eggs, in the United States National 

 Museum collection, average 59.5 by»40 millimeters; the eggs show- 

 ing the four extremes measure 65.5 by 42, 62.5 by 43, 55 by 42, 

 and G0.5 by 38 millimeters. 



Young. — Incubation lasts for about 21 days and is shared by both 

 sexes. The young remain in the nest, or in the crevices among the 

 rocks near it, for a long time and are fed by their parents until they 

 are fully fledged or nearly so and ready to learn to fly. The prin- 

 cipal food of the young seems to be rock eels, small fish, and other 

 soft-bodied sea animals which their parents find among the sea- 

 weed and rocks at low tide or obtain by diving. 



Plumages. — The young when first hatched are covered with thick 

 down which is uniform sooty blackish above, and paler or more 



