This section is from the book "The Bird Book", by Chester A. Reed. Also available from Amazon: The Bird Book.
Range. - North Atlantic coasts and islands, breeding from Bird Rock northward. Murres are similar in form to the Guillemots, but are larger, being about 16 inches in length. Entire head and neck sooty brown; rest of upper parts grayish black except the tips of the secondaries which are white. Under parts white. These birds nest by thousands on Bird Rock and on the cliffs of Labrador. They build no nests but simply lay their single egg on the narrow ledges of cliffs, where the only guarantee against its rolling off is its peculiar shape which causes it, when moved, to revolve about its smaller end instead of rolling off the ledge. The eggs are laid as closely as possible on the ledges where the incubating birds sit upright, in long rows like an army on guard. As long as each bird succeeds in finding an egg to cover, on its return home, it is doubtful if they either know or care whether it is their own or not. The ground color of the eggs vary from white to a deep greenish blue and the markings of blackish brown vary in endless patterns, some eggs being almost wholly unspotted. Size 3.40 x 2. Data. - South Labrador, June 19, 1884. Single egg laid on the bare cliff. Large colony breeding. Collector, M. A. Grazar.
Pale bluish gray.
MURRE - White, buff, or deep greenish blue.
Range. - Pacific Coast, breeding from the Farallones north to Alaska.
This Pacific form of the common Murre is the most abundant breeding bird on the Farallones. Their eggs are used in enormous numbers for commercial purposes and these islands being located, as they are, within easy distance from San Francisco, thousands of dozens of the eggs are sold yearly, chiefly to bakeries. Although continually robbed, their numbers have not as yet diminished to any great extent. They lay but a single egg on the bare ledge. Individual eggs are indistinguishable from the last species but in a large series the ground color averages brighter. They show the same great difference in color and markings. The first set is laid in May, but owing to their being so often molested, fresh eggs can be found during August. Data. Farallones, July 4, 1895. Single egg laid on bare cliff. Collector, Thos. E. Slevin.