The Petrel’s nests were composed of fine grasses and a few feathers, and one nest contained two bits of white birch bark, the presence of which raised the question as to whether these gleaners of the sea do not gather suitable nesting material when they find it floating on the surface of the water. Two of the eight or ten Petrels’ nests examined contained a single white egg; one egg constituting a full set with this species, as with all the other rock-nesting birds, except the Kittiwake. The remaining nests were each occupied by a newly hatched young bird—a gray ball of down, so unlike anything in feathers I had ever seen that, if it had not been for their tiny, young chickenlike _peep_, I should have been inclined to pass it by as a wad of gray cotton.^{96} Never more than one of the parent birds, either the male or female, was found on the nest, nor was a single Petrel seen about the Rock during the day. [Illustration: 96. Young Leach’s Petrel removed from burrow with nesting material.] The Puffins and Petrels are now the only birds nesting on the summit of the Rock, not a single descendant of the one hundred thousand Gannets which, according to Bryant, occupied the top of the Rock in 1860 now being found there. To-day this species nests only on the less accessible border ledges on the face of the Rock, where they are grouped in colonies. Most of them were incubating, but several were brooding their young, which ranged in size from the naked, black-skinned, newly hatched chick to those that had acquired the white, swan’s-downlike first plumage.^{97} With the exception of two white, black-spotted birds, all the Gannets seen, both on Bird Rock and Bonaventure, were in the adult white plumage, and if, as has been stated, this plumage is not gained until the bird is two years old, the question arises, What becomes of the immature birds during the nesting season? [Illustration: 97. Young Gannet.] An estimate of the number of individuals representing the seven species just mentioned as nesting on the Rock, is perhaps not warranted by my brief experience, nor should I attempt to give one, did not my photographs permit me to count with a fair degree of accuracy the number of birds in view on that part of the Rock shown in these pictures. Time was lacking to make, from a boat, a series of photographs of the Rock which would include all its bird-inhabited portions, and the appended estimates are based on the results of a count of the birds in photographs of about one half the occupied area. Murres, Razorbills, and Puffins can not be distinguished in these pictures and are therefore grouped under one head, it being calculated that about from fifteen hundred to two thousand individuals of these species make the Rock their home. Of this number probably not more than one hundred are Puffins, while the Common and Brünnich’s Murres (_Uria troile et U. lomvia_) outnumber the Razorbills at least four to one.