MANX SHEARWATER, Puffinus Anglorum. — Local name "Cockle". Resident.
The Manx Shearwater is, without doubt, the most interesting of our Pembrokeshire birds, from the fact that Skomer Island is the largest breeding-station, and may be considered the metropolis, of the species in the British Isles. The numbers there are almost incredible. And yet any visitor to Skomer in the day time, who left the island before night, would probably fail to see a solitary Shearwater, and if he was ignorant of the indications of their presence, might depart quite unaware of the vast bird population slumbering beneath his feet. For, during the day, the "Cockles" are all asleep in their burrows; some of these they have stolen from, and perhaps share with the rabbits, others they have excavated for themselves. Some of the burrows go straight in, but the greater number have various turns and twists, so that it is a tedious business, sometimes, to dig to and to reach the single white egg, which is almost the size of an ordinary hen's egg. We have sometimes met small parties of these Shearwaters abroad on the sea during the day-time, and during the autumn we have seen the water covered by large flocks of them throughout the day, but certainly at the nesting season they are almost exclusively nocturnal, and do not come out from their holes to feed until quite late at night.
One beautiful summer's night that we spent on Skomer, with Mr. Mortimer Propert, for the purpose of making acquaintance with the Shearwaters, we were greatly surprised at the late hour they emerged from their burrows. We went out several times after sunset to search for them, but all in vain, none had appeared. Several times we resumed our game at whist in Mr. Vaughan Davies' hospitable house, before we went out and were successful in discovering that the birds were at last upon the move, and this was close upon eleven p.m. The birds were then flying in numbers over the ground to and fro about the height of our heads, almost brushing our faces as they flitted past. Their strange wailing cry resounded on all sides, and they kept up an unearthly chorus until the first streak of dawn. We saw numbers come forth from holes at our feet, flapping with their wings for a yard or two along the ground before they were able to rise into the air, and it seemed as if it was necessary for them that the ground should slightly incline downwards, in order that they might gain a bite upon the air. The old sheep-dog of the farm was with us, and amused herself by catching the Shearwaters one after another, and bringing them uninjured to our hands. Not wanting any, we would then toss them up into the air, and let them go, once or twice getting the benefit of a vomit of the greenish oil which the bird is able to discharge, either when frightened, or for the purpose of defence. We watched the birds for a long time in the calm and semi-twilight of the beautiful night, and it appeared as if they flew about the island for a long time before going out to sea, and that others were constantly coming in again from the water. There seemed, indeed, no diminution in the numbers flying over the island all through the night, for when we at last retired to bed, we still heard the same wailing cries, often close outside our bedroom window. It was not until day dawned that the chorus gradually died away, and rising early, and going out to take a walk over the island, we detected but a single Shearwater sitting at the entrance of its burrow, into which it scuttled on our approach. Thrusting our arm inside, we found that it was a straight burrow, as, lying down, we were just able to touch the egg at its end, also the bird. Mr. Vaughan Davies informed us that one year he ploughed cartloads of the poor "Cockles" into the ground for manure, setting boys at night to knock them down with sticks, and to kill them, as they came out of their holes.
Numbers of Manx Shearwaters nest on the adjoining island of Skokholm, which is uninhabited, and is merely a summer run for sheep. A few may nest on Ramsey Island, and we have seen the birds in Ramsey Sound, but Mr. Mortimer Propert is not sure that they do. The Shearwaters are occasionally seen in flocks in Fishguard Bay. We were for some time doubtful, and rather incredulous, as to any Shearwaters nesting on Caldy, which in our opinion seemed too tame an island for them, but after the evidence that we subjoin, it is without question that a few do so, or at least upon the connected island of St. Margaret's. In the summer of 18S7, Mr. E. W. H. Blagg, who was then staying at Tenby, informs us that several evenings he saw a large flock of Manx Shearwaters flying off Caldy Island, and believed that the birds nested there. Mr. Dix states, "numbers breed at Caldy Island," but we had an idea that they had ceased to do so since he wrote this, a quarter of a century ago. On several occasions, when we ourselves have visited Tenby, on making inquiries, we failed to find anyone who could tell us if there were still Shearwaters upon Caldy; indeed, we were once expressly told that no such birds were known upon the island. Writing to us upon this point, Mr. C. Jefferys, of Tenby, states: "The Manx Shearwater used to breed upon Caldy, and I think a few still do now in the fissures of the cliffs. I can give you more decided information about St. Margaret's Island, which, as you know, is connected with Caldy by a reef of rocks, dry at low water. While on this island last May (1893) I frightened out of holes and fissures four or five Manx Shearwaters ; they appeared to come from cracks about half-way down the cliffs, and may, or may not, have been nesting there; it certainly looks as if they were." We believe, ourselves, that the "Cockles" only frequent and nest on islands where there is a sufficient quantity of soil upon the top for them to dig their burrows, and that they are for this reason absent from islands that are mere rock, but this would certainly not apply to Caldy, which is suitable to the birds in every respect, except that it is too much run over, and the birds may therefore have been frightened away from it.
M Mathew, 1894, The Birds of Pembrokeshire and its islands.