Page:The British Warblers A History with Problems of Their Lives - 8 of 9.djvu/31

 not bear the stamp of genuine effort; perhaps they are but excesses of the irresistible impulse which must clearly dominate the situation at that time. The male probably aids his mate in her work, though I have not actually seen him doing so; he at least keeps a close attendance upon her and a careful watch on all her movements, never deserting her for long and apparently only too anxious to return to her when summoned. Whilst following her he may warble for a few moments, and sometimes a quiet purring note is uttered by both sexes; but during this time individuals of other species who approach the scene of operations too closely are flown at and attacked. Two or three days are sufficient for the completion of the nest, which is by no means an elaborate piece of architecture; flimsy it is in appearance and circular in shape, the exterior and foundation being composed of dead grasses rudely bent and entwined, and the interior of grasses of a finer type. The lining, which covers the foundation and reaches some distance up the walls, is composed of fine roots. In appearance the foundation is the most delicately constructed portion, and one wonders how it can be of sufficient strength to support the young. In circumference the nest is approximately from 13" to 15", the external diameter about 4½", and the internal from 2" to 2½". The walls vary in thickness even in the same nest; thus in one part they may be 1" full, whereas in another about ½" only. One peculiar variation I have in my possession. It has the appearance of—and I believe actually is—two nests in one. The external depth is 5" as against the customary 2", the internal depth 2", and the circumference rather above the average. The most interesting feature, however, about this nest is the remarkable resemblance it bears to one type of nest of the Marsh Warbler. It is composed of similar materials, is similar in shape, and, more curious still, similarly slung from the surrounding twigs by basket handles. It was situated in a dense mass of dogwood, and coming upon it whilst searching for the nest of a Marsh Warbler, I was